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PAPERmaking! The e-magazine for the Fibrous Forest Products Sector

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The Paper Industry Technical Association

Volume 6 / Number 2 / 2020

PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

CONTENTS: FEATURE ARTICLES: 1. Packaging: Enhancing packaging board with micro- and nano-fibres. 2. Pulps: Effect of softwood kraft fines on strength properties. 3. Printing: Effect of papermaking conditions on print quality. 4. Maintenance: Fault detection using nearest neighbour-based feature extraction. 5. Paper Chemistry: Analysis of AKD retention to solve online problems. 6. Wood Panel: Morphological characteristics of MDF dust. 7. Fillers: Chitosan-modified PCC fillers for paper applications. 8. Tissue: Synthesis of a new cationic polyamine Yankee coating agent. 9. Waste Treatment: CO2 capture capacity of lime mud. 10. Driving: Various tips to improve driving performance. 11. Telephone Skills: Tips about phone etiquette. 12. Video Conferencing: Dos and don’ts for those remote working. 13. Management: Tips for new managers. 14. Personal Development: Signs of a professional mid-life crisis. 15. Leadership: The importance of empathy. 16. PITA History Parts 1-3: Extended articles covering 1920-2000. SUPPLIERS NEWS SECTION: Products & Services:

Section 1 – PITA Corporate Members: ABB / ANDRITZ / TOSCOTEC / VALMET Section 2 – Other Suppliers

Ametech / Henkel / InfraTec / Signal Group / Stanley / Tsubaki DATA COMPILATION: Installations: Overview of equipment orders and installations since May 2020 Research Articles: Recent peer-reviewed articles from the technical paper press Technical Abstracts: Recent peer-reviewed articles from the general scientific press Events: Information on forthcoming courses / events / webinars

The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology International and the PITA Annual Review, both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating.

Page 1 of 1

Contents

PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Enhancing packaging board properties using micro and nanofibers prepared from recycled board Ossi Laitinen, Terhi Suopajärvi, Henrikki Liimatainen. In this study, cellulose microfibers and cellulose nanofibers (CNF) prepared from recycled boxboard pulp using a mechanical fine friction grinder were used as reinforcements in a board sheet. Micro and nanofibers manufactured by mechanical grinding have typically broad particle size distribution, and they can contain both micro- and nano-sized fibrils. Deep eutectic solvent of choline chloride and urea was used as a nonhydrolytic pretreatment medium for the CNF, and reference CNF were used without any chemical pretreatment. The CNF were ground using three grinding levels (grinding time) and their dosage in the board varied from 2 to 6 wt%. The results indicate that the board properties could be tailored to obtain a balance between the processability and quality of the products by adjusting the amount of CNF that was added (2–6 wt%). A preliminary cost assessment indicated that the most economical way to enhance the board strength properties was to add around 4% of CNF with a moderate grinding level (i.e., grinding energy of 3–4 kWh/kg). Overall, the strength properties of the manufactured board sheets improved by several dozen percentages when CNF was used as the reinforcement. Contact information: Fiber and Particle Engineering, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland Cellulose (2020) 27:7215–7225 https://doi.org/10.1007/s10570-020-03264-w(0123456789().,-volV()0123456789().,-volV) This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// creativecommons.org/licenses/by/4.0/)

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Article 1 – Enhancing Packaging Board

Cellulose (2020) 27:7215–7225 https://doi.org/10.1007/s10570-020-03264-w

(0123456789().,-volV) (0123456789().,-volV)

ORIGINAL RESEARCH

Enhancing packaging board properties using microand nanoﬁbers prepared from recycled board Ossi Laitinen

. Terhi Suopajärvi . Henrikki Liimatainen

Received: 13 January 2020 / Accepted: 23 May 2020 / Published online: 29 May 2020 Ó The Author(s) 2020

Abstract In this study, cellulose microfibers and cellulose nanofibers (CNF) prepared from recycled boxboard pulp using a mechanical fine friction grinder were used as reinforcements in a board sheet. Microand nanofibers manufactured by mechanical grinding have typically broad particle size distribution, and they can contain both micro- and nano-sized fibrils. Deep eutectic solvent of choline chloride and urea was used as a non-hydrolytic pretreatment medium for the CNF, and reference CNF were used without any chemical pretreatment. The CNF were ground using three grinding levels (grinding time) and their dosage in the board varied from 2 to 6 wt%. The results indicate that the board properties could be tailored to obtain a balance between the processability and quality of the products by adjusting the amount of CNF that was added (2–6 wt%). A preliminary cost assessment indicated that the most economical way to

Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10570-020-03264-w) contains supplementary material, which is available to authorized users. O. Laitinen (&) T. Suopajärvi H. Liimatainen Fiber and Particle Engineering, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland e-mail: ossi.laitinen@oulu.fi T. Suopajärvi e-mail: terhi.suopajarvi@oulu.fi H. Liimatainen e-mail: henrikki.liimatainen@oulu.fi

enhance the board strength properties was to add around 4% of CNF with a moderate grinding level (i.e., grinding energy of 3–4 kWh/kg). Overall, the strength properties of the manufactured board sheets improved by several dozen percentages when CNF was used as the reinforcement. Keywords Boxboard Cellulose nanoﬁbers Deep eutectic solvents Fine friction grinding Microﬁbers Nanocellulose Reinforcement

Introduction The production of nano-scale cellulose fibers (nanocelluloses) and their application as reinforcements in materials have gained increasing attention due to the high strength and stiffness of the nanocelluloses combined with their small size, high surface area and aspect ratio, low weight, biodegradability, and renewability (Siró and Plackett 2010; Hassan et al. 2011; Suopajärvi et al. 2017). Cellulose nanofibrils or nanofibers (CNF) produced by mechanical disintegration of cellulose without any chemical treatments are one of the simplest types of nanomaterials based on renewable resources. CNF manufactured by mechanical treatments alone are polydisperse with a broad particle size distribution, and they can contain both micro- and nano-sized fibrils (Kangas et al. 2014).

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CNF have both amorphous and crystalline components, and they form of a web-like structure (Lavoine et al. 2012). The mechanical fibrillation process causes permanent changes in the cellulose fiber structure, and it increases the bonding ability of cellulose by modifying the morphology and reducing the size of the fibers (Kamel 2007; da Costa Correia et al. 2016). Thus, some previous studies have shown that CNF can notably improve the mechanical properties of paper or board. It has been found that tensile strength and elastic modulus can be improved significantly (Eriksen et al. 2008; Hii et al. 2012; Sehaqui et al. 2013; González et al. 2013; Missoum et al. 2013; Djafari Petroudy et al. 2014; Hietala et al. 2016). High tensile strength and tensile stiffness contribute to the stacking strength of corrugated paperboard by reducing the risk of box wall bulging; thus, they are desired properties of board applications. The global increase in packaging board and fiber products consumption has yielded a large amount of potential secondary cellulose raw materials that contribute to 25–40% of municipal solid waste (Nourbakhsh and Ashori 2010). Recycling these fiber sources and their use as raw materials for new sustainable products can preserve forest resources and minimize other environmental impacts. Moreover, fibers from recycled paper and packaging are relatively affordable and widely available. Therefore, they offer an appealing source for the production of packaging materials and novel green materials, such as CNF. The use of bio-based and recycled fiber sources to create sustainable packaging materials to replace plastics derived from fossil oil resources promotes the emerging trend of mitigating the carbon footprint of materials. The successful liberation of nanofibrils require typically rigorous mechanical treatments due to the strong hydrogen-bonded structure of cellulosic materials. Thus, numerous different chemical pretreatments have been used to loosen the rigid structure of cellulose. Deep eutectic solvents (DESs) belong to the most promising group of novel green chemicals to enable efficient CNF production (Selkälä et al. 2016; Li et al. 2017, 2018; Sirviö 2018; Ojala et al. 2018). DESs can be derived from biodegradable and readily available green compounds that have a low toxicity (Sirviö et al. 2015). DESs are typically synthesized by complexation of the hydrogen bond acceptor (HBA),

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such as a halide salt of quaternary ammonium or a phosphonium cation along with a hydrogen bond donor (HBD) (e.g., urea, glycerol, or ethylene glycol), to form a mixture that exhibits a notably lower melting point than either HBA or HBD. In the present work, a DES system based on choline chloride and urea (Singh et al. 2012) was used as a pretreatment to liberate CNF from recycled boxboard using mechanical grinding. The CNF obtained from a secondary cellulose source were further used as reinforcements in board sheets. CNF produced directly from recycled board without any chemical treatments were used as the reference additives. Nanopapers were produced from the CNF to evaluate their strength properties. Moreover, the work evaluated the optimal grinding level in CNF production to maximize the energy consumption and costs of manufacturing CNF for use as board reinforcements.

Materials and methods Raw material and chemicals Chemicals used Urea (97%) and choline chloride ([ 98%) for DES were purchased from Borealis (Austria) and Algry Quimica (Spain), respectively. All chemicals were used as delivered, without any further puriﬁcation. In the dilutions and CNF production, deionized water was used throughout the experiments. Raw material Recycled boxboard was obtained directly from boardcontainer collections, and it was used as the raw material for the board sheets and the production of the CNF. The boxboard was ﬁrst pulped without any additional chemicals using a Kenwood Chef Titanium XL pulper (UK) with a nominal rotor power of 1700 W, which has an operating principle similar to that of the Hobart pulper, at a consistency of 15% using a temperature of 45 °C. Pulper using a planetary type mixing during pulping procedure. The mixer and pulping bowl were manufactured in stainless steel. Pulping time was adjusted to 10 min and rotor speed 2 (i.e., * 250 rpm). After pulping, the recycled boxboard pulp was washed and screened using a Somerville screen (Lorentzen and Wettre, Sweden).

Cellulose (2020) 27:7215–7225

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The conductometric titration procedure described by Rattaz et al. (2011) and Katz et al. (1984) was used to determine the charge density of the pulp. The hemicellulose content was determined with the TAPPI-T 212 om-02 standard and alkali solubility at 25 °C was determined with the TAPPI-T 235 cm-00 standard. The lignin content was determined using TAPPI-T 222 om-02 standard. Moreover, the extractive content was analyzed using SCAN-CM 49:03 standard and ash content was determined using the ISO1762 standard. The chemical properties of the board raw material are shown in Table 1. The average (length-weighted) length and width of the board ﬁbers after washing were determined with a Valmet FS5 Fiber analyzer ultra-high deﬁnition (UHD) camera unit (Finland). Three replicates of each sample were measured, and the results were averaged and shown in Table 2. Production of CNF from the recycled boxboard DES of choline chloride and urea was used as a pretreatment to produce CNF from the boxboard pulp. The DES solution was produced by heating 1620 g of choline chloride and 1223 g of urea in a large beaker (5 dm3) at 100 °C until the mixture melted, after which it was placed into a water bath at 100 °C under constant stirring for approximately 5 min to obtain a clear and colorless liquid. Then, 25 g (abs) of recycled board material (dry matter content of * 30%) was added to the suspension and mixed for 2 h. Then, the beaker was removed from the water bath and 1000 cm3 of deionized water was added while mixing (Sirviö et al. 2015). Next, four identical DES-treated batches of boxboard pulp were combined. Then, the treated board was washed with water using a Somerville screen (Lorentzen and Wettre) until clear rinse water was obtained. After completing the washing procedure, the DEStreated pulp was disintegrated with a Masuko supermasscolloider grinder (MKCA6-2J, Japan) using three different grinding times (grinding energy) to obtain

three different CNF samples: T1, T2, and T3 (Table 3). The stones of the grinder were first carefully brought into close contact, as determined by the low friction sound, and then the pretreated pulp slurry was poured into the grinder at a consistency of 1.5%. First, the pulp was passed through the grinder three times using a zero-grinding stone gap (sample: T0); after which the stones were adjusted to negative gap values in order to start the actual fibrillation. The energy consumption of the fibrillation procedure was recorded with an energy meter (iEM3250 SchneiderElectric, France) attached to the fine friction grinder. The board pulp passed through the grinder a total of 14 times, using negative gap values of 3 times - 20 lm, 1 time - 40 lm, 1 time - 50 lm, 1 time - 60 lm, 3 times - 80 lm, and 5 times - 90 lm to obtain different board CNF (Table 3). The reference CNF samples were obtained from untreated boxboard pulp using a similar procedure. The reference samples are named: U0, U1, U2 and U3. Manufacture and characterization of the investigated materials Visualization of CNF and the board samples After being subjected to different grinding energies, the board pulps were visualized using a Valmet FS5 Fiber analyzer UHD camera unit. Field emission scanning electron microscope (FESEM) (Zeiss Ultra Plus, Germany) was used for the samples obtained after a longer grinding time because of their much smaller average particle size and the need for a higher magnification. As a pretreatment, the FESEM samples were filtered using a polycarbonate membrane with a pore size of 0.2 lm (Whatman). Then, the filtration samples were rapidly frozen with liquid nitrogen and freeze-dried in a vacuum overnight. The dried samples were sputter-coated with platinum. An accelerating voltage of 5 kV and a working distance of around 5 mm was used when imaging the samples.

Table 1 Chemical properties of the recycled boxboard pulp Sample

Charge (mmol/g)

Cellulose (wt%)

Hemicel-lulose (wt%)

Lignin (wt%)

Extrac-tives (wt%)

Ash (wt%)

Board

- 0.19

57.5

16.4

13.3

0.8

12.3

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Table 2 Fiber properties of the recycled board pulp ground with a ﬁne friction grinder including standard deviation of measurements Sample

Fiber length (mm)

Fiber width (lm)

0.763 ± 0.018

19.27 ± 0.70

0.148 ± 0.001

6.42 ± 0.04

0.053 ± 0.002

3.60 ± 0.10

Fines A1, 0–0.04 mm (%)

Fines A2, 0.04–0.08 mm (%)

Fines A3, 0.08–0.12 mm (%)

Fines A4, 0.12–0.16 mm (%)

Fines A5, 0.16–0.20 mm (%)

1.94 ± 0.24

1.25 ± 0.07

0.85 ± 0.04

0.68 ± 0.04

0.65 ± 0.03

20.72 ± 0.09

11.39 ± 0.04

5.7 ± 0.02

3.69 ± 0.03

2.72 ± 0.02

44.63 ± 1.19

22.93 ± 0.27

9.47 ± 0.32

4.91 ± 0.18

2.87 ± 0.14

0.042 ± 0.002

2.14 ± 0.09

64.77 ± 2.25

24.41 ± 0.94

7.06 ± 0.77

2.18 ± 0.35

0.69 ± 0.15

0.787 ± 0.033

19.53 ± 0.84

1.42 ± 0.16

1.02 ± 0.04

0.74 ± 0.03

0.69 ± 0.02

0.64 ± 0.01

0.138 ± 0.003

6.66 ± 0.09

22.96 ± 0.21

11.87 ± 0.09

6.45 ± 0.08

4.35 ± 0.08

3.11 ± 0.07

0.057 ± 0.001

4.39 ± 0.11

38.96 ± 0.87

20.91 ± 0.43

10.01 ± 0.26

5.94 ± 0.16

4.00 ± 0.01

0.037 ± 0.001

1.87 ± 0.09

72.51 ± 1.89

21.37 ± 1.26

4.58 ± 0.46

1.05 ± 0.12

0.26 ± 0.03

Table 3 Energy consumption of the CNF production and the strength properties of the CNF nanopapers including standard deviation of measurements Sample

Description

Grinding time (min)

Energy consumption (kWh/ kg)

T0 T1

Fibers CNF

T2 T3 U0

Fibers

CNF

1.0

CNF

135

Strain (%) 1.32 ± 0.01 2.54 ± 0.01

1220.0 ± 6.4

156.1 ± 12.6

7.61 ± 0.09

1459.2 ± 0.4

181.8 ± 24.1

9.95 ± 0.13

597.5 ± 24.4

16.7 ± 0.4

1.12 ± 0.01

832.1 ± 42.0

36.7 ± 0.6

1.89 ± 0.01

2.6

1109.9 ± 67.3

102.7 ± 6.8

5.46 ± 0.02

9.9

1418.1 ± 23.0

154.2 ± 18.4

9.35 ± 0.16

0 1.6

CNF

3.7

CNF

114

8.8

The surface structure of different handsheets was visualized directly from the surface of the prepared handsheets, which were sputtered with platinum before observation under the FESEM with 5 kV voltage. Testing the strength properties of the nanopapers produced from board treated with CNF Nanopapers were produced by filtration of 0.3 g (abs) of the fibrillated board samples on a polyvinylidene fluoride membrane (Durapore) with a pore size of 0.65 lm and a diameter of 70 mm. After filtration, the wet sheets were covered with a similar membrane and then dried with a Rapid–Köthen sheet dryer (Karl Schröder KG, Germany) under a vacuum of 0.1 bar at a temperature of 93 °C for 10 min (ISO 5269-2:2004). The samples were stored at ISO 187 standard

568.4 ± 8.0 881.9 ± 26.6

Tensile strength (MPa) 14.0 ± 0.1 66.0 ± 3.4

0 37

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Density (kg/ m3)

conditions of 23 °C and 50% relative humidity. After preconditioning for at least 48 h in the standard environment, ﬁve thicknesses of the sample in different locations were measured using a precision thickness gauge (Hanatek FT3, UK), and the results were averaged. Six strips with a width of 5 mm were used for the actual strength measurements. The tensile tests were performed with a Zwick D0724587 (Switzerland) universal material testing machine using a 100 N load cell (Table 3). During the tensile tests, six replicates of each sample were tested using the standard conditions of 23 °C temperature and 50% relative humidity. The gauge length was adjusted to 40 mm at a strain rate of 4 mm/min.

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Manufacturing and testing of the board handsheets Laboratory handsheets were prepared from recycled boxboard pulp using various dosages (0%, 2%, 4%, or 6%) of CNF as a reinforcement. CNF were added directly to the pulp board slurry without any other chemical additives. Board sheets with 160 g/m2 grammage were prepared in a laboratory sheet-forming machine (Lorentzen and Wettre) according to the ISO 5269-1 standard method. The board handsheets were conditioned before testing at 23 °C in 50% relative humidity according to the ISO 187 standard. Eight handsheets which means in practice at least eight replicates of each sample were tested using the standard conditions. The grammage and thickness of the handsheets were measured according to ISO 536 and ISO 534 standards. The tensile strength of the board handsheets was measured with a Zwick D0724587 universal material testing machine according to the ISO 1924-2 standard using 15 mm 9 141 mm test strips. The internal bond strength of the paperboard (z-direction tensile strength) was measured with a Zwick D0724587 machine according to the TAPPI T541, 09/2005 standard. The tearing strength was measured with the Lorentzen and Wettre Tearing Tester according to TAPPI T414 om-12.

Results and discussion Characteristics of the board fibers and CNF The visual appearance of the DES-treated board fibers and CNF obtained from grinding (Fig. S1) were studied with Valmet FS5 Fiber analyzer UHD camera unit (samples T0, T1, T2, and T3). Furthermore, example images (Fig. S2) of the DES-treated CNF (T2 and T3) were obtained with FESEM. Length weighted fiber length and width of each sample are presented in Table 2. The optical resolution of FS5 UHD camera unit is close to 1 lm, which means that the smallest particles are not visible in practice and thus not included in the calculations. Length of the fibers decreased from around 0.8 mm (T0/U0) to 40 lm (T3/ U3), when grinding time increased and finally led to a suspension containing mainly CNF (i.e., U3 and T3). Also fiber width decreased from around 19 lm (T0/ U0) to around 2 lm (T3/U3). The proportion of fines

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(i.e., particles which length and width are smaller than 200 lm) were mainly in the two smallest size categories (i.e., 0–40 lm and 40–80 lm) with U3 and T3 samples while in primary board pulp (T0/U0) there is only around 5% fines. Based on the fiber analysis, the fiber properties of the DES-pretreated samples and the samples without chemical treatment (reference samples) were similar. The surface structure of the board handsheets (160 g/m2) was visualized directly from the surface of the prepared sheets with the absence (Fig. 1a) and the presence of additional reinforcement CNF (T1, T2 and T3, Fig. 1b–d). CNF were observed on the surface of the handsheets, and smaller fibrils were visible on the surface of the sheets when the fibrillation level increased (i.e., T3 vs. T1/T2). Energy consumption of the CNF production and the strength properties of the nanopapers Table 3 presents the grinding energy demand for the production of the CNF reinforcements. The grinding time varied from 0 to 114 min, while the corresponding energy consumption was 0–8.8 kWh/kg of product. The consumed energy used in this research was well in line what have been noticed earlier in many publications related to mechanical fine friction grinding (Eriksen et al. 2008; Klemm et al. 2011; Laitinen et al. 2017; Ämmälä et al. 2019). The reinforcement potential of CNF was evaluated from the nanopapers fabricated directly from CNF without board fibers (Table 3). Overall, the strength properties of the CNF obtained from the DES-treated samples were better in comparison to the CNF produced using mechanical grinding without chemical pretreatment, and the strength increased as a function of grinding time. For example, the tensile strength of the nanopapers from the DES-treated CNF increased from 14.0 to 181.75 MPa (T0 and T3), while the maximum tensile strength of the reference CNF was 154.17 MPa (U3). These values are comparable to many of the recently published strength values of lignocellulosic nanopapers and films (Spence et al. 2010; Rojo et al. 2015; Visanko et al. 2017; Hietala et al. 2018). Mechanical properties of the board handsheets The CNF produced from recycled boxboard were used as a reinforcement in the board handsheets. During the

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Fig. 1 Surface structure of the board handsheets with the absence and presence of CNF as reinforcements; a board from 100% of T0; b board containing 6 wt% of T1; c board containing 6 wt% of T2; d board containing 6 wt% of T3

preparation of the handsheets, the drainage time was observed to increase almost linearly (Fig. 2) as a function of the reinforced CNF dosage, which varied from 2 to 6 wt%. Moreover, the increase in the grinding time of the ﬁbers decreased the water removal, i.e., it increased the drainage time (U1 ? U2 ? U3). A similar trend was observed for the DEStreated and reference CNF. However, the total retention of the board handsheets were very high (from approx. 97.5–99.5%), which was in practice 97.5%

Fig. 2 Drainage time of the board handsheets

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with the highest dosage of reinforcement CNF (6 wt%) and with CNF of the smallest size (U3 and T3). This indicates that the retention of the reinforcement CNF was also high without the use of any retention chemicals (around 70%). The reinforcement of the mechanical properties of the board sheets by the addition of CNF is most likely connected to the enhanced bonding between the board ﬁbers promoted by the CNF (da Costa Correia et al. 2016). Therefore, CNF can increase the density and stiffness of a sheet, and decrease the sheet bulk. In the present study, the highest density (Fig. 3) and lowest bulk (Fig. S3) were observed, as expected, in the board sheets with the highest amount (6 wt%) of the most ﬁbrillated reinforcement CNF (U3). For example, the sheet density increased from 577 to 684 kg/m3, while bulk decreased from 1.73 to 1.46 cm3/g with U3. Density trends and therefore in turns bulk trends seems to be similar in both for the DES-treated and reference CNF. The tear index and strain of the board handsheets are presented as a function of the CNF reinforcement (Fig. 4.) Both the tear index and strain increased with larger CNF dosages, except for the sheet containing U1. However, the effect of CNF on the tear strength was either relatively small or it plateaued at low dosages. Furthermore, the improvement in strain

Cellulose (2020) 27:7215–7225

Fig. 3 Densities of the prepared board handsheets

induced by CNF was very small (\ 1% unit). Generally, the DES-treated CNF sample resulted in better values than the reference CNF. To evaluate the costs attributed to using CNF as reinforcements in the board handsheet, some preliminary calculations were conducted. The estimated price of the electricity was 0.13 €/kWh; the price of recycled boxboard was 0.08 €/kg. Technical grade of urea costs around 200 €/t and choline chloride around 350 €/t (Laitinen et al. 2017). We used in these calculations recycling rate of 10 times and efﬁciency of chemical recycling 97% and the used consistency of pulp solution during DES-treatment was 5%. Based on

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calculations chemical pretreatment with used DESsystem increased the raw material cost from 0.08 to 0.107 €/kg, which is around 34%. We noticed also that both the grinding level of CNF and their loading in the board sheet have a significant impact on the final price of the board. For example, increasing the T3 dosage from 2 to 6 wt% increased the final product price of the board by approximately 160–212%. Overall, the costs associated with using DES-treated CNF were around 30% higher when compared to reference CNF (Figs. S4–S6) recycled board. Because the energy consumption, chemical costs and costs associated with CNF use increased notably when the CNF grinding level increased, the most important mechanical properties of the board were compared to the energy consumption and relative manufacturing price of the strengthened recycled board to analyze the optimal use of CNF as a reinforcement. The tensile strength of the handsheets increased almost linearly as a function of the CNF dosage (Fig. 5). CNF treated with DES enhanced the tensile strength to a greater extent than the addition of reference CNF (Fig. 5), and the highest strength value was obtained with T3. The best tensile strength index was 61% higher (i.e., T3 [6%]) than that of the reference board handsheet (34.0 kNm/kg). Moreover, it was observed that pulp from the DES-pretreatment had better strength properties in comparison to the untreated pulp. However, by considering the total chemical costs associated with the pulp slurry

Fig. 4 Tear index (a) and strain values (b) of prepared board handsheets

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pretreatment, a more economical way to enhance the strength properties would be to add untreated mechanical grinded CNF as the reinforcement. Of the CNF used, the samples obtained from moderate grinding (U2) resulted in the most cost-efﬁcient board sheets (Fig. S4). The obvious reason for this phenomenon is that the energy consumption of grinding increased signiﬁcantly at the end of the grinding process (i.e., U2 ? U3), while the improvement in strength properties was not as pronounced. The trend for the tensile stiffness index of the board sheets was similar to the trend for the tensile strength index (Fig. 6). A nearly linear increase in the tensile

stiffness index was observed, and a maximum increase of 27% was noted with the CNF treated with DES and the highest grinding level (T3). Furthermore, the most economical way to increase the tensile stiffness was to add the CNF with a moderate grinding level (i.e., U2, Fig. S5). For example, the 6 wt% dosage of T2 resulted in a tensile stiffness index of approximately 5.5 MNm/kg with a relative cost of 160%, while cost related to the use of the 6 wt% of U3 was approximately 190% with the stiffness index of approximately 5.3 MNm/kg. In the best case, the tensile stress (z-direction tensile strength) was 85% higher (i.e., T3 [6%]) than that of the reference board handsheet (i.e., without grinding) (Fig. 7). However, the differences between the DES-treated CNF and the reference CNF were small. Similar to the tensile strength and stiffness values, the most cost-efﬁcient use of reinforcement was to add the CNF with the moderate grinding levels (i.e., U2) to enhance the z-direction tensile strength (Fig. S6). Overall, the results clearly demonstrate that the best way to improve the mechanical properties of the board sheet was to add approximately 4 wt% of untreated mechanical grinded CNF from the moderate grinding levels (those that used grinding energy 3–4 kWh/kg) as a reinforcement material. Doing so only increased the relative price of the manufactured board by 15–20%, but the tensile strength index improved 25–40%, the tensile stiffness index was 10–20%, and the z-direction tensile strength was 40–60% (Fig. S4–

Fig. 6 Comparison of the tensile stiffness index based on the amount of reinforcement ﬁber of the prepared board handsheets

Fig. 7 The tensile stress (z-direction tensile strength) reinforcement ﬁber amount of the prepared board handsheets

Fig. 5 Tensile strength index against reinforcement ﬁber amount of the prepared board handsheets

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Table 4 Comparison of the improved strength properties of paper products published in recently Publication

Reinforced ﬁber

Added amount (%)

Retention agent/ﬁller

Increase of tensile strength (%)

Increase of z-direction tensile strength (%)

Final product

Eriksen et al. (2008)

Kraft pulp CMF

1–8

No/no

7–21

Not analyzed

TMP

Hii et al. (2012)

SW kraft pulp CMF

2.5–5

Yes/yes

3–13

20–35

Newsprint grade TMP

Djafari Petroudy et al. (2014)

Mechanical and enzymatic treated CMF

1–5

Yes/no

22–40

Not analyzed

Bagasse pulp

Hellström et al. (2014)

Fenton and enzymatic treated CNF

Yes/yes

5–35

2–50

CTMP

Su et al. (2014)

HW kraft pulp CMF

Yes/no

270–300

Not analyzed

HW kraft pulp

Delgado-Aguilar et al. (2015a)

Tempo-oxidized CNF

1.5–4.5

Yes/yes

40–82

32–56

Deinked pulp

Hassan et al. (2015)

Enzymatic and TEMPOoxidized CNF

2.5–20

No/no

14–62

Not analyzed

Softwood and bagasse pulps

Delgado-Aguilar et al. (2015b)

HW kraft pulp CNF

Yes/no

70–200

Not analyzed

HW kraft pulp

Brodin and Eriksen (2015)

Carboxymethylated and fractionated TMP

0–20

No/no

1–15

Not analyzed

TMP

Mashkour et al. (2015)

Acetylated CNF

0–10

Yes/no

0–17

Not analyzed

SW kraft pulp

Hietala et al. (2016)

Dicarboxyl acid cellulose CNF

0.25–4

Yes/yes

0–21

Not analyzed

Fluting board

Suopajärvi et al. (2017)

Kraft pulp, Fluting and Board CNF

Yes/yes

12–34

Not analyzed

Kraft pulp, Fluting and Board

Tajik et al. (2018)

Bagasse pulp CNF

0.1–2

Yes/no

15–49

Not analyzed

Bagasse pulp

Bossu et al. (2019)

SW kraft pulp CMF

1–10

No/no

3–48

1–95

SW kraft pulp

This study

Boxboard CNF

2–6

No/no

1–45

2–85

Recycled boxboard

This study

DES-treated boxboard CNF

2–6

No/no

11–60

20–72

Recycled boxboard

S6). Obviously, the board strength properties can still be improved by adding CNF with a higher grinding level ([ 4 kWh/kg) or by increasing the amount of reinforced CNF ([ 4 wt%), but this is not meaningful from an economic point of view. Furthermore, higher dosages of CNF from higher grinding levels would increase the drainage time and cause problems in the actual board manufacturing process. Moreover, it must be highlighted that the total chemical costs needed for the DES-pretreatment and the recycling of chemicals (i.e., urea and choline chloride) increased relative much (around 30%) of the ﬁnal product price when DES-treatment is used in the CNF preparation. In summary, the results suggest that the grammage of prepared board could be decreased by adding CNF as the reinforcement material, and the treated product would still achieve similar strength properties as the original board without any reinforced ﬁbers.

In the Table 4 have been compared improved strength properties of different paper products published in recent years. As can be noticed different nanocellulose reinforced ﬁbers have typically a positive impact on the strength properties of various paper products, but some of research’s were used very expensive chemicals and very energy intensive grinding method like high pressure homogenization instead of mechanical grinding. Additionally, most of studies focused on paper strengthening and only a few scientiﬁc studies have focused on the effects of CNF on paperboard properties.

Conclusions This study’s ﬁndings showed that, by selecting suitable grinding levels and dosages of CNF, it is

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possible to notably enhance the strength of the board sheet. Moreover, a balance between the board processing parameters (retention, drainage time) and the board mechanical properties can be achieved by tailoring the amount of CNF that is added. The strength properties of the manufactured board sheets improved several dozen percentages when CNF obtained from recycled boxboard was used as a reinforcement. It was also observed that the strength properties of the pulp from the DES-pretreatment were better than those of the untreated pulp. However when taking account chemical pretreatment with used DESsystem the raw material cost increased around 34% and therefore the most economical way to improve the tensile strength properties of boards is to add untreated mechanical grinded CNF with around a 4% moderate grinding level (using a grinding energy level around 3–4 kWh/kg) directly to the board pulp slurry as the reinforcement material. Acknowledgments Open access funding provided by University of Oulu including Oulu University Hospital. The authors would like to acknowledge the funding provided by the Council of Oulu Region, granted by the European Regional Development Fund of the European Union for the New bioproducts and—chemicals from cellulose side streams using DES-based refining concept project (SelDES). Compliance with ethical standards Conflict of interest The authors declare that they have no conflict of interest. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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7225 barrier, mechanical and surface properties of nanocellulose films. Green Chem 17:1853–1866. https://doi.org/10.1039/ C4GC02398F Sehaqui H, Zhou Q, Berglund LA (2013) Nanofibrillated cellulose for enhancement of strength in high-density paper structures. Nord Pulp Pap Res J 28:182–189 Selkälä T, Sirviö JA, Lorite GS, Liimatainen H (2016) Anionically stabilized cellulose nanofibrils through succinylation pretreatment in urea-lithium chloride deep eutectic solvent. Chemsuschem. https://doi.org/10.1002/cssc.201600903 Singh BS, Lobo HR, Shankarling GS (2012) Choline chloride based eutectic solvents: magical catalytic system for carbon-carbon bond formation in the rapid synthesis of bhydroxy functionalized derivatives. Catal Commun 24:70–74. https://doi.org/10.1016/j.catcom.2012.03.021 Siró I, Plackett D (2010) Microfibrillated cellulose and new nanocomposite materials: a review. Cellulose 17:459–494. https://doi.org/10.1007/s10570-010-9405-y Sirviö JA (2018) Cationization of lignocellulosic fibers with betaine in deep eutectic solvent: facile route to charge stabilized cellulose and wood nanofibers. Carbohydr Polym 198:34–40. https://doi.org/10.1016/j.carbpol.2018. 06.051 Sirviö JA, Visanko M, Liimatainen H (2015) Deep eutectic solvent system based on choline chloride-urea as a pretreatment for nanofibrillation of wood cellulose. Green Chem 17:3401–3406. https://doi.org/10.1039/C5GC0039 8A Spence KL, Venditti RA, Rojas OJ et al (2010) The effect of chemical composition on microfibrillar cellulose films from wood pulps: water interactions and physical properties for packaging applications. Cellulose 17:835–848. https://doi.org/10.1007/s10570-010-9424-8 Su J, Zhang L, Batchelor W, Garnier G (2014) Paper engineered with cellulosic additives: effect of length scale. Cellulose 21:2901–2911. https://doi.org/10.1007/s10570-014-0298-z Suopajärvi T, Sirviö JA, Liimatainen H (2017) Nanofibrillation of deep eutectic solvent-treated paper and board cellulose pulps. Carbohydr Polym 169:167–175. https://doi.org/10. 1016/j.carbpol.2017.04.009 Tajik M, Torshizi HJ, Resalati H, Hamzeh Y (2018) Effects of cationic starch in the presence of cellulose nanofibrils on structural, optical and strength properties of paper from soda bagasse pulp. Carbohydr Polym 194:1–8. https://doi. org/10.1016/j.carbpol.2018.04.026 Visanko M, Sirviö JA, Piltonen P et al (2017) Mechanical fabrication of high-strength and redispersible wood nanofibers from unbleached groundwood pulp. Cellulose 24:4173–4187. https://doi.org/10.1007/s10570-017-1406-7 Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Softwood kraft pulp fines: application and impact on specific refining energy and strength properties Daniel Mandlez, Lukas Zangl-Jagiello, Rene Eckhart, Wolfgang Bauer. Along with the emergence of micro and nanofibrillated celluloses and their application in papermaking, the influence of the so called fines fraction of pulps on both process and product properties has received increasing research interest in recent years. Several researchers have experimented with primary and/or secondary pulp fines to assess their effects on paper properties with not always consistent results. Our work focuses on the targeted application of the primary fines fraction of an unbleached softwood kraft pulp. The primary fines are separated from the pulp to be subsequently added to achieve blends of 5%; 9% and 12% primary fines content. These blends were then refined in a PFI mill to evaluate the effect of the primary fines on refining as well as on paper properties of hand sheets prepared from these pulps. It is shown that the addition of primary fines enhances tensile strength in the unrefined and slightly refined state, while the maximum tensile strength of the highly refined reference pulp is not increased. A slightly increased dewatering resistance (Schopper Riegler) at comparable air permeability (Gurley) for a given tensile strength was also observed. The linear relationship between tensile index and apparent sheet density seems to be affected in the unrefined and slightly refined state where the breaking length of the fines enriched samples is higher for a given apparent density. Contact information: Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, Graz 8010, Austria Cellulose https://doi.org/10.1007/s10570-020-03467-1 This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// creativecommons.org/licenses/by/4.0/)

Page 1 of 10

Article 2 – Softwood Pulp Fines

Cellulose https://doi.org/10.1007/s10570-020-03467-1

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ORIGINAL RESEARCH

Softwood kraft pulp fines: application and impact on specific refining energy and strength properties Daniel Mandlez . Lukas Zangl-Jagiello . Rene Eckhart

. Wolfgang Bauer

Received: 3 July 2020 / Accepted: 15 September 2020 Ó The Author(s) 2020

Abstract Along with the emergence of micro and nanofibrillated celluloses and their application in papermaking, the influence of the so called fines fraction of pulps on both process and product properties has received increasing research interest in recent years. Several researchers have experimented with primary and/or secondary pulp fines to assess their effects on paper properties with not always consistent results. Our work focuses on the targeted application of the primary fines fraction of an unbleached softwood kraft pulp. The primary fines are separated from the pulp to be subsequently added to achieve blends of 5%; 9% and 12% primary fines content. These blends were then refined in a PFI mill to evaluate the effect of the primary fines on refining as well as on paper properties of hand sheets prepared from these pulps. It is shown that the addition of primary fines enhances tensile strength in the unrefined and slightly refined state, while the maximum tensile strength of the highly refined reference pulp is not increased. A slightly increased dewatering resistance (Schopper Riegler) at comparable air D. Mandlez R. Eckhart (&) W. Bauer Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, Graz 8010, Austria e-mail: rene.eckhart@tugraz.at L. Zangl-Jagiello Zellstoff Pöls AG, Dr. Luigi-Angeli-Str. 9, Pöls 8761, Austria

permeability (Gurley) for a given tensile strength was also observed. The linear relationship between tensile index and apparent sheet density seems to be affected in the unrefined and slightly refined state where the breaking length of the fines enriched samples is higher for a given apparent density. Keywords Fines Pulp Softwood Refining Beating PFI

Introduction In the evaluation of fibre morphological properties of any given pulp it is standard to differentiate between the coarse and the fines fraction. The fines fraction is commonly either defined as material passing a 76 lm screen (200 mesh) in a Britt Dynamic Drainage Jar Device (according to SCAN-CM 66:05), or particles smaller than 200 lm in case of determination by automated optical analysis (according to ISO 16065-2) (Mayr et al. 2017b). Depending on their origin, pulp fines have different morphological character and are usually divided in primary and secondary fines (Odabas et al. 2016). Primary fines are produced during the pulping process and mainly consist of blocky or flake like material, which is mostly ray cells, parenchyma cells, pores and fragmental parts from the middle lamella (Odabas et al. 2016). Secondary fines

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are generated during refining in the stock preparation process and have a strong fibrillar character, as they mainly consist of fibrils torn from the fibre wall structure during pulp refining (Retulainen et al. 1993). Besides this highly fibrillar material, fibre fragments resembling primary fines are also produced during refining due to fibre cutting and shortening. A certain proportion of fibrillar material, however, is also present in primary fines. Hence the distinction between primary and secondary fines is to some extent more a definition of origin of the pulp fines than of morphological properties, although it will always reflect the morphology to large part as well. In order to improve the strength properties of paper it is necessary to increase the relative bonded area and/ or specific bonding strength (Dasgupta 1994; Motamedian et al. 2019). This increase can be achieved by sheet densification, which is positively influenced by addition of fine cellulosic materials such as micro or nanofibrillated celluloses or pulp fines, therefore leading to an increase in tensile properties (Bäckström et al. 2008; Taipale et al. 2010). In contrast to such micro or nanofibrillated celluloses (Sandquist 2013), which need substantial amounts of energy in production, fines may be directly accessible from process streams like filtrates, or could be separated from the pulp using suitable aggregates (Hinck and Wallendahl 1999). Due to their different morphological character, primary and secondary fines have a different effect on sheet properties. As the mainly fibrillar material of the secondary fines shows higher surface area and stronger swelling, it has a stronger effect on bonded area and therefore a stronger influence on strength properties of paper compared to the more blocky primary fines (Ferreira et al. 2000; Fischer et al. 2017; Mayr et al. 2017a, b; Motamedian et al. 2019; Odabas et al. 2016). Still, also fine cellulosic materials defined as secondary fines can differ in their fibrillar material content, respectively their fibrillar area (Mayr et al. 2017a). These differences are on the one hand caused by the pulp type being refined and on the other hand by different refining conditions in terms of specific edge load and varying refining intensities (Mayr et al. 2017b). While for secondary fines their effect on strength properties has extensively been reported by several researchers, this is not the case for primary fines, where only a few studies are available focusing on the effects of their removal or addition on paper

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technological properties (Bäckström et al. 2008; Chauhan et al. 2012; Ferreira et al. 1999, 2000; Mayr et al. 2017b; Motamedian et al. 2019). Due to the differences in experimental designs, these studies did not always show consistent results. Chauhan et al. (2012), for example, show that the addition of up to 10 and 20% w/w of primary fines, separated from bleached hardwood kraft pulp by means of a Bauer McNett classifier, prior to refining leads to reduced strength properties of papers produced from these pulp blends after PFI refining compared to the reference without the addition of primary fines. Ferreira et al. (1999), on the other hand, show that removal of primary fines from unbleached hardwood kraft pulp, leads to a decrease in tensile and burst index, but an increase in tear index. In this case, primary fines were removed by a Bauer McNett classifier equipped with a 200 Mesh screen. Results by Bäckström et al. (2008) in an experimental design, where primary fines were added to the pulp, again show that the addition of either primary or secondary fines to refined fibres allows an improvement of tensile index, burst index and TEA. Fines were separated with a Celleco laboratory filter equipped with a 100 lm mesh size cloth. The fine fraction was further separated by a 20 lm cloth and the passing fraction discarded to exclude colloidal fines material from the investigation. The fines content was determined acording to TAPPI Standard T261. Our work focuses on the effect of different addition rates of primary fines of a softwood kraft pulp to the same pulp and on the effect of this addition rate on pulp and paper properties. The rates of addition are chosen in a range that corresponds to amounts of fines that may also be produced by refining in industrial stock preparation. The blends of pulp and primary fines are evaluated in the unrefined as well as in the refined refined state. Thereby the evolvement of e.g. tensile properties due to addition of fines and/or refining is accessible and allows the assessment of possible savings in refining energy through the addition of in our case primary fines.

Cellulose

Experimental Materials An industrial, never dried, unbleached softwood kraft pulp containing 85% spruce, 10% pine and 5% larch with Kappa number 27 was used in all trials. The primary fines content of the pulp was 5% determined according to SCAN-CM 66:05. A part of the primary fines fraction of this pulp was separated using a laboratory scale pressure screen implemented at the Institute for Bioproducts and Paper Technology at Graz University of Technology. Methods In order to separate the primary fines fraction, a laboratory scale pressure screen (Fig. 1) equipped with a 100lm hole screen (Fig. 2) was used. The reference pulp was fed to the pressure screen at a volume flow V_ F of 10 l/min at a consistency of 0.5% (w/w). The accept passing the screen with a volume flow V_ A of 4 l/min and a consistency of approximately 0.015% (w/w), was collected in vessels for sedimentation. With this process 12.5 g dry of primary fines per 1 kg dry pulp was separated. The supernatant was decanted after adequate time for sedimentation to reach a dry content of 0.5% for subsequent application. The coarse fraction was discarded. Pulp/primary fines blends Samples with a total fines content of 9 and 12% w/w were obtained by adding the necessary amount of previously separated primary fines to the reference pulp having a primary fines content of 5% w/w.

Fig. 2 Micro perforated 100 lm hole screen installed in the laboratory pressure screen

Samples containing 30g dry matter (pulp ? primary fines) were diluted to a consistency of 1,5% w/w for disintegration according to ISO 5263-1. For subsequent PFI refining the samples were thickened to a consistency of 10% w/w by filtration. To avoid loss of fines during filtration, the filtrate from thickening was added to the filter cake several times. After thickening the reference pulp and the pulp/primary fines blends were refined in a PFI mill for 1000, 4500 and 6000 revolutions (ISO 5264-2). Pulp properties Fibre morphology was determined using a L&W fibre Tester?. This optical flow microscopy analyzer has an optical resolution of 3:3 lm=pixel. Samples containing 0.1 g dry matter were analyzed and measurements were repeated three times. For each repetition a minimum of 100.000 particles was detected. Results are discussed based on length weighted fibre length distributions according to ISO 16065-2. The total fines content was determined using the Britt Dynamic Drainage Jar (BDDJ) according to SCAN-CM 66:05 using a 200mesh screen. The degree of beating of the samples was determined according to ISO 5267-1 (Schopper Riegler method). The separated primary fines were characterized using a light microscopy, based imaging method developed by Mayr et al. (2017a). In this method 5g of fines suspension at 0,01% consistency is prepared with deionized water. This sample is mixed with 0,06g of an emulsion working as a fixing agent for subsequent staining with methylene blue. This emulsion is prepared by mixing 5g of deionized water with 0.01g crude tall oil. The mixture is emulsified at 80 C in an ultrasonic bath for

Fig. 1 Laboratory scale pressure screen

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30 minutes. After the addition of methylene blue to the sample for enhanced contrast of the fines in imaging, microscopy sample holders were prepared with three droplets of the stained fines suspension and dried on a heating plate. Three sample holders per blend were prepared and 200 pictures were taken for each sample. Figure 3 shows an exemplary image depicting fibrils and flakes. Automated image analysis was applied based on MATLABÒ to obtain values for average equivalent circle diameter of either fibrils and flakes as well as the fibril area (in %) (Mayr et al. 2017a). In addition to the microscopy based characterisation described above we used an Alicona Infinite Focus Measurement device allowing imaging using so called shape from focus. Thereby imaging is possible at 50 fold magnification (corresponds to 0:625 lm=pixel) without the usual problems with depth of focus arising when you look at three dimensional particles at high resolution. Imaging was done based on the same samples described above. These imaging method (Fig. 4) gives a much more detailed qualitative impression of the fines and their morphological characteristics. Hand sheets forming Hand sheets of 80g=m2 using the unrefined and refined reference pulp and the unrefined and refined pulp / primary fines blends were prepared according to ISO 5269-3 on a Rapid Köthen hand sheet former using white water recirculation to avoid losses of primary fines due to retention issues (Giner et al. 2015).The

Fig. 4 Microscope image of separated primary fines taken with an Alicona infinite focus measurement with a magnification of 50

first four hand sheets were discarded to reach an equilibrium of fines in the recirculated white water and to achieve a 100% retention of the primary fines (Giner et al. 2015). Hand sheets properties Hand sheet testing was performed after conditioning the samples for at least 24 hours in the climate room at 23 C and 50% relative humidity. Apparent sheet density was determined according to ISO 534, tensile properties according to ISO 1924-2 and Gurley air permeability according to TAPPI 460 om-16.

Results and discussion Pulp properties of reference pulp and pulp/primary ﬁnes blends

Fig. 3 Exemplary microscope image showing flakes and fibrils, a flakes, b fibrils

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Figure 5 shows the cumulative length weighted fibre length distribution of the separated primary fines with the L&W fibre Testerþ , showing that 94% of the material is smaller than 200 lm with the remaining 6% of the separated material being below a maximum length of 400 lm.

Cellulose 100

AV ECD Fibril [ m]

0 0

100

150

200

250

300

350

400

450

500

Fig. 5 Cumulative length weighted ﬁbre length distribution of separated primary ﬁnes

This cumulative fibre length distribution clearly shows that the separated material consists almost exclusively of fines and contains hardly fibres at all. Still, the evaluation of fines in such a flow cell is prone to misinterpretation of the material due to two reasons. On the one hand the fines already are—at least in one dimension—close to the minimum resolution of such a measurement device. On the other hand, especially fibrilar material is highly swollen and tends to show too low contrast to be accessible for such a device. Therefore the method based on microscopy and subsequent image analysis (Mayr et al. 2017b) is necessary, to assess the morphological properties of the fines material. This method (Fig. 6) shows, that besides the expected flake like material also a significant amount of fibrillar material is present in the separated primary fines. This is also confirmed by the the high value for fibril area (Fig. 7), showing that

Fibril Area [%]

AV ECD Flake [ m]

Fig. 7 Characterization data of separated primary fines showing average equivalent circle diameter of fibrils and flakes as well as the fibril area (errorbars indicate 95% confidence interval)

60% of the projected area is fibrillar content. In comparison the fibril area of bleached softwood secondary fines is in a range of up to 75% when measured with the given method (Mayr et al. 2017b). The average equivalent circle diameter (ECD) of fibrils and flakes are of compareable size. As there is a considerable amount of fibrillar material also present in primary fines (see also Fig. 4), the positive effect of primary fines on strength properties should not be underestimated. The cumulative length weighted fibre length distribution of the reference pulp and the pulp/primary fines blends in the unrefined and the refined state obtained with the L&W fibre Testerþ are depicted in Fig. 8. While the influence of primary fines addition is highly significant, a comparably low influence of refining on the fibre length distribution is visible. This shows that only a low amount of secondary fines was generated and that hardly any shortening of long fibres occurred during PFI refining, indicating that the PFI mill treatment leads mainly to fibre flexibilisation due 100 90 80 70 60 50 40 30 20 10 0 0

Fig. 6 Microscope image of the separated primary ﬁnes

1000

2000

3000

4000

5000

6000

Fig. 8 Cumulative length weighted fibre length distribution of blends after refining in comparison to the unrefined references

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to internal fibrillation, which has also been reported elsewhere (Gharehkhani et al. 2015; Kerekes 2005; Wang et al. 2007). One of the pulp property related parameters that is expected to be affected due to fines addition is dewaterability. Still, in the unrefined state the effect on dewatering (based on degree of beating SR) is barely noticeable (Fig. 9). For low refining intensity of 1000 PFI revolutions an increase in dewatering resistance is noticeable especially at 12% addition rate of primary fines. This effect becomes even more pronounced at higher refining intensities of 4500 and 6000 revolutions in the PFI mill. For the 12% primary fines/pulp blend refined at 6000 PFI revolutions, the degree of dewatering resistance expressed as SR was more than 50% higher than the reference sample containing 5% of primary fines. Based on the morphological evaluation of the blends it can be stated, that in case of the chosen

Fig. 9 Development of dewatering resistence (Schopper Riegler), Gurley air permeability and breaking length due to reﬁning (errorbars indicate 95% conﬁdence interval)

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refining aggregate barely any fines are created for all the assessed refining levels. The refining treatment almost exclusively affects the properties of the fibre material. Therefore, the technological effect of the dosed primary fines is directly accessible at different refining levels of the given pulp. Paper properties of handsheets prepared from reference pulp and pulp/primary fines blends A similar behavior as for the dewaterability of the reference pulp and pulp/primary fines blends is evident for air permeability (Fig. 9) with the effect of fines addition being more significant at 4000 and 6000 PFI revolutions. It seems, that the additional fines present in the pulp tend to affect air permeability and dewatering especially in already denser networks formed of more flexible fibres where they are capable of blocking the already smaller remaining pores. When it comes to mechanical properties there clearly is a positive effect on breaking length (Fig. 9) due to the addition of primary fines. This effect is reduced for higher refining intensities and therefore already densified sheets up to the point where no significant difference in breaking length is evident after 6000 revolutions in the PFI mill. However, when it comes to applying a such treated softwood unbleached kraft pulp in paper production the main interest is to reach a certain level of tensile strength, as in industry that kind of pulp is refined to reach a certain strength level. The corresponding dewatering properties are an inevitable secondary effect that is taken into account but not adjusted to a certain target. Looking at the relationship between air permeability and tensile strength (Fig. 10) or dewatering resistance and tensile strength (Fig. 11) it becomes evident that the addition of primary fines does not have a significant effect on this relationship. Tensile strength (breaking length) tends to level out at higher dewatering resistance while air resistance still increases further. The blend containing 12% primary fines shows a slightly higher dewatering resistance (SR ) at a given breaking length already at lower refining intensities; at an addition level of 9% such a trend is not observed. In case of air permeability (Fig. 10), no significant difference is evident whether primary fines are added or not. It is also evident that the addition of primary fines does not allow to increase tensile strength above a certain maximum level, which

Cellulose

Fig. 10 Air permeability (Gurley)—breaking length relationship of the different pulp/primary ﬁnes blends (errorbars indicate 95% conﬁdence interval)

Fig. 11 Dewatering resistance (Schopper Riegler)—breaking length relationship of the different pulp/primary ﬁnes blends (errorbars indicate 95% conﬁdence interval)

also can be achieved by just refining the pulp. This maximum level of tensile strength is determined by the pulp itself and seems to be a kind of intrinsic pulp property. Several other publications are also demonstrating this behavior for refined pulps and as a consequence of fines addition (Joseleau et al. 2012; Kerekes 2005; Lin et al. 2007; Odabas et al. 2016). Both air permeability and dewatering resistance are affected by sheet densification due to flexibilisation of the fibres during refining on the one hand and by blocking of the pores by presence of additional fines on the other hand. Apparent sheet density is directly related to tensile strenght (breaking length) as it is shown in Fig. 12 . This clearly linear relationship between sheet density and tensile strength is to be expected as higher apparent densitie leads to an increase in relative bonded area and thus tensile

Fig. 12 Apparent density—breaking length relationship of the different pulp/primary ﬁnes blends (errorbars indicate 95% conﬁdence interval)

properties. The significant effect of fines on sheet densification and its consequence for mechanical properties has already been reported in the past (Retulainen et al. 2002). In principle, it should be irrelevant how this densification is achieved, be it by fibre flexibilization, fibre shortening and/or generation of fines. However, a slight increase of breaking length for a given apparent density is generated by the addition of primary fines. An explanation for this observation could be that the increased amount of primary fines in case of less refined and thus less flexible pulp fibres generates additional bonded area due to an aggregation of the fines in the interstices between two crossing fibres during dewatering. The improvement of fibre fibre bonding due to fines acting as a kind of bridging material has already been described in the literature (Bäckström et al. 2008). At higher refining intensities leading to a higher degree of flexibilization, this effect is less pronounced and no significant difference between the reference and the two blends with additionally added primary fines is evident for denser sheets above 700 [kg=m3 ]. An explanation for this behaviour may be that at such high densities with the breaking length approaching 10 kilometers and more the strength of single fibres starts to affect the strength of the sheet and bonded area is not as dominant as it is at lower densities. Overall, an increase in the amount of primary fines shows the potential to reach a desired level of tensile strength in slightly refined pulps at reduced refining energy demand, giving less dense (i.e. more bulky

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sheets) at a similar or slightly increased level of dewatering resistance.

Conclusion and outlook For unbleached softwood kraft pulp the addition of primary fines originating from the same pulp leads to an increase in tensile strength in the unrefined state as well as at low refining intensities. The maximum achievable level of tensile strength on the other hand is not increased by the addition of primary fines, but stays at the level of the reference. However, in terms of refining energy the addition of primary fines shows the potential to reach a certain level of tensile strength at lower refining energy consumption at similar or only slightly increased dewatering resistance. At the same time the apparent density is slightly lower at a given tensile strength in the unrefined state and at low refining intensities. At higher refining intensities the addition of primary fines does not contribute to the level of tensile strength, as the fibre network is already highly densified due to fibre flexibilization in PFI refining. Here, additionally added primary fines mainly tend to block pores and thereby increase dewatering resistance and reduce air permeability. In this laboratory study, primary fines showed a positive contribution to fibre fibre bonding at lower refining intensities. A direct comparison to the effect of secondary fines generated during refining is not possible based on this study, as only a very low amount of secondary fines was produced during the PFI refining. This will have to be observed, when it comes to the applicability of our results under industrial conditions, which is planned as a next step in our evaluations. An industrial refiner will produce a higher amount of additional secondary fines and might also show some fibre shortening during refining. It will therefore be interesting to see, to which extent the results of these trials in an industrial setting differ from the findings reported in this lab study. Acknowledgments We are grateful for the support by our industry partners in the frame of the FLIPPR2 project, Mondi, Sappi, Zellstoff Pöls AG, a member of Heinzel pulp, and Papierholz Austria. The K-Project FLIPPR2 is funded as part of COMET-Competence Centers for Excellent Technologies promoted by BMVIT, BMWFW, Styria and Carin-thia. The COMET program is managed by FFG.

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Funding Open access funding provided by Graz University of Technology. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

References Bäckström M, Kolar MC, Htun M (2008) Characterisation of fines from unbleached kraft pulps and their impact on sheet properties. Holzforschung 62(5):546–552. https://doi.org/ 10.1515/HF.2008.081 Chauhan VS, Kumar N, Kumar M, Thapar SK, Chakrabarti SK (2012) Use of primary fiber fines as organic fillers in papermaking. Taiwan J Forest Sci 27(2):201–214 Dasgupta S (1994) Mechanism of paper tensile-strength development due to pulp beating. Tappi J 77(6):158–166 Ferreira PJ, Matos S, Figueiredo MM (1999) Size characterization of fibres and fines in hardwood kraft pulps. Part Part Syst Char 16(1):20–24 Ferreira PJ, Martins A, Figueiredo M (2000) Primary and secondary fines from Eucalyptus globulus kraft pulps. characterization and influence. Paperi Puu-Pap Tim 82(6):403–408 Fischer W, Mayr M, Spirk S, Reishofer D, Jagiello L, Schmiedt R, Colson J, Zankel A, Bauer W (2017) Pulp fines-characterization, sheet formation, and comparison to microfibrillated cellulose. Polymers 9(12):366. https://doi. org/10.3390/polym9080366 Gharehkhani S, Sadeghinezhad E, Kazi SN, Yarmand H, Badarudin A, Safaei MR, Zubir MNM (2015) Basic effects of pulp refining on fiber properties—a review. Carbohyd Polym 115:785–803. https://doi.org/10.1016/j.carbpol. 2014.08.047 Giner Tovar R, Fischer WJ, Eckhart R, Bauer W (2015) White water recirculation method as a means to evaluate the influence of fines on the properties of handsheets. Bioresources 10(4):7242–7251 10.15376/biores.10.4.7242-7251 Hinck JF, Wallendahl U (1999) Improving sulfite pulp quality and mill operations through the removal of fines. Orlando, Florida, pp 601–608 Joseleau JP, Chevalier-Billosta V, Ruel K (2012) Interaction between microfibrillar cellulose fines and fibers: Influence on pulp qualities and paper sheet properties. Cellulose

Cellulose 19(3):769–777. https://doi.org/10.1007/s10570-012-96935 Kerekes R (2005) Characterizing refining action in PFI mills. Tappi J 4(3):9–14 Lin T, Yin X, Retulainen E, Nazhad MM (2007) Effect of chemical pulp fines on filler retention and paper properties. Appita J 60(6):469 Mayr M, Eckhart R, Bauer W (2017a) Improved microscopy method for morphological characterisation of pulp fines. Nord Pulp Pap Res J 32(02):244–252. https://doi.org/10. 3183/NPPRJ-2017-32-02-p244-252 Mayr M, Eckhart R, Thaller A, Bauer W (2017b) Characterization of fines quality and their independent effect on sheet properties. In: Transactions of the 16th Fundamental Research Symposium Held in Oxford pp 299–322 Motamedian HR, Halilovic AE, Kulachenko A (2019) Mechanisms of strength and stiffness improvement of paper after PFI refining with a focus on the effect of fines. Cellulose 26(6):4099–4124. https://doi.org/10.1007/s10570-01902349-5 Odabas N, Henniges U, Potthast A, Rosenau T (2016) Cellulosic fines: properties and effects. Prog in Mater Sci 83:574–594. https://doi.org/10.1016/j.pmatsci.2016.07.006

Retulainen E, Moss P, Nieminen K (1993) Effect of fines on the properties of fibre networks. In: Products of papermaking 10th Fundamental Research Symposium pp 727–769 Retulainen E, Luukko K, Fagerholm K, Pere J, Laine J, Paulapuro H (2002) Papermaking quality of fines from different pulps—the effect of size, shape and chemical composition. Appita J 55(6):457–467 Sandquist D (2013) New horizons for microfibrillated cellulose. Appita J 66(2):156–162 Taipale T, Österberg M, Nykänen A, Ruokolainen J, Laine J (2010) Effect of microfibrillated cellulose and fines on the drainage of kraft pulp suspension and paper strength. Cellulose 17(5):1005–1020. https://doi.org/10.1007/ s10570-010-9431-9 Wang X, Maloney TC, Paulapuro H (2007) Fibre fibrillation and its impact on sheet properties. Paperi Ja pPuu 89(3):148–153 Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Effect of Papermaking Conditions on the Ink Absorption and Overprint Accuracy of Paper Yuanfeng Dong (a), Binshou Wang (b), Hairui Ji (b), Wenyuan Zhu (c), Zhu Long (a), Cuihua Dong (b,c). The ink-absorption capacity is an important factor for evaluating the printing quality of paper. In this study, the effects of different parameters of papermaking on the ink-absorption capacity of paper were investigated. The results showed that hardwood pulp exhibited better performance in increasing the absorptivity of paper compared with softwood pulp. When the content of hardwood pulp in paper was increased from 0% to 100%, the ink mark length decreased from 5.1 cm to 4.3 cm. Furthermore, a basis weight change from 100 g/m2 to 60 g/m2 increased the ink-absorption capacity, as revealed by a decrease of the ink mark length from 4.8 cm to 4.4 cm. Both sizing agent and beating degree affected the ink-absorption performance of the paper. For example, a shorter ink mark length of 5.1 cm was obtained at a low beating degree of 5000 r compared with that of 5.1 cm at 15000 r. Contact information: a: Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, China; b: School of Light Industry Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 300175, China; c: Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing, 210037, China. Dong et al. (2020). “Ink absorption and overprint,” BioResources 15(1), 1397-1406. (check out other issues of this excellent journal at https://bioresources.cnr.ncsu.edu/) DOI: 10.15376/biores.15.1.1397-1406 This article is open access.

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Effect of Papermaking Conditions on the Ink Absorption and Overprint Accuracy of Paper Yuanfeng Dong,a Binshou Wang,b Hairui Ji,b Wenyuan Zhu,c Zhu Long,a,* and Cuihua Dong b,c,* The ink-absorption capacity is an important factor for evaluating the printing quality of paper. In this study, the effects of different parameters of papermaking on the ink-absorption capacity of paper were investigated. The results showed that hardwood pulp exhibited better performance in increasing the absorptivity of paper compared with softwood pulp. When the content of hardwood pulp in paper was increased from 0% to 100%, the ink mark length decreased from 5.1 cm to 4.3 cm. Furthermore, a basis weight change from 100 g/m 2 to 60 g/m2 increased the ink-absorption capacity, as revealed by a decrease of the ink mark length from 4.8 cm to 4.4 cm. Both sizing agent and beating degree affected the ink-absorption performance of the paper. For example, a shorter ink mark length of 5.1 cm was obtained at a low beating degree of 5000 r compared with that of 5.1 cm at 15000 r. Keywords: Ink absorption; Pulp; Sizing; Beating Contact information: a: Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, China; b: School of Light Industry Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 300175, China; c: Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing, 210037, China; * Corresponding authors: longzhu@jiangnan.edu.cn; xiaodong771111@163.com

INTRODUCTION Printing technology continues evolving with the development of society (Kwon and Kim 2007; Kim et al. 2012). Paper is one of the most important printing substrates and has played an important role in the improvement of printing speed and quality, especially paper with high ink-absorption capacity (Havlínová et al. 1999). The strength of the ink absorption significantly affects the printing hue of the printed matter and the glossiness. If the adsorption of paper to ink is too fast, then the vehicles in ink will penetrate into paper too much, resulting in a printing product that looks dull. Otherwise, the bad adsorption of paper to ink will reduce the drying rate of printing product, which will further result in a dirty product (Jiang et al. 2011; Pjanic and Hersch 2015). Paper is a porous material, unlike other substrates such as plastic film or tinplate. It has a layered structure similar to soil and sedimentary rock, and is accompanied by many capillary structures (Reme and Helle 2002; Chinga-Carrasco 2009). Because the voids formed by the fiber network are the basis for the ink absorption of paper, the absorption capacity of the ink is an important quality index of printing papers. In recent decades, various advanced tools and techniques have been used to study the penetration of ink into papers; microscopy has received much attention due to its accurate and efficient capture of the infiltration details of ink in papers. Ngo et al. (2017) used scanning electron microscopy (SEM) to investigate the ink penetration of different coated paper cross-sections. Heard et Dong et al. (2020). “Ink absorption and overprint,” BioResources 15(1), 1397-1406.

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al. (2004) and Sodhi et al. (2008) studied the distributions of ink components in printed coated paper by combining focused ion beam (FIB) techniques with a transmission electron microscope (TEM). Yan and Li (2008) and Ozaki (2011) researched the penetration of the ink vehicle by staining it with a fluorescent dye and obtained a 3-D characterization using confocal laser scanning microscopy (CLSM). Li and He (2011) employed ultravioletcuring fluorescent rose ink as a substitute and investigated the penetration and distribution of ink pigments by CLSM. Combining the microstructure of paper and transforming the properties of the osmotic liquid to achieve lateral diffusion leads to penetration and solidification on the papers (Enomae et al. 2012). For printing products, the ink absorption of the paper is only one aspect affecting the quality, and the overprinting accuracy of printed patterns is another factor. It is mainly manifested in the surface compressibility of the paper. This study explored the absorption properties of papers by changing the basis weight, pulp, beating, and sizing of papers. The IGT system was used to simulate the actual printing environment and perform the ink absorption experiment, exploring the effects of basis weight, pulp, beating, and sizing on the absorption of papers. Moreover, using digital printers to compare the overprinting precisions of papers with different basis weights and different fiber compositions, it was shown that the overprinting precision of hardwood paper was significantly greater than that of softwood paper, and as the paper basis weight increased, the overprinting accuracy decreased. EXPERIMENTAL Materials The bleached kraft pulp of polar and pine was procured from Asia Symbol (Shandong) Pulp and Paper Co., Ltd. (Rizhao, Shandong, China). Alkyl ketene dimer (AKD) was provided by Shandong Chemicals Company. It was prepared into solution with a consistency of 10f0.5% and viscosity of 15 mPaЬS at 25 °C. Di-n-butyl phthalate solution with 0.1% pigment (Sudan Red) was used to act as printing ink. Methods Beating of pulp Pulp samples were beaten in a PFI mill (A-8, Norway) at 10% stock consistency. The interspaces between the beating roll and beating chamber were 0.18 mm, and the load applied during refining was 3.4 N/mm. The beating degree was measured by the drainage of pulp. Analysis of fiber morphology Analysis of fiber morphology was performed using an OpTest Fiber Quality Analyzer (FS-5, OpTest Equipment Inc., Hawkesbury, ON, Canada). Observation of fiber morphology and paper surface aperture by polarized light microscope The surface topography of the papers was observed (10×10) using an NP-800M polarized light microscope (PLM, Nanjing Jiangnan Novel Optics Co., Ltd, Nanjing, China).

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Preparation of handsheets To test the effect of sizing treatment on ink absorption, handsheets of 70 g/m2 were prepared by putting the required softwood pulp (1%), AKD (0.1%) and water into the disintegrator and using the Rapid Kothen Sheet Former machine (RK-3A, Austria). The paper was vacuum-heated and dried at 95 qC for 10 min. Without special explanation, sizing agent was not present in other samples. Before testing, all the samples were treated at 23 °C and 65% relative humidity for 24 h. Determination of ink absorption The ink droplets between the printing plate and the paper strip in the sector of the IGT printing applicator (GST-1, IGT Testing Systems, Almere, Netherlands) were 5.8 mg ± 0.3 mg and spread out. The ink mark length was measured as an indicator of absorption capacity; the ink mark length increases as the absorbability of the paper decreases. Determination of overprint accuracy The handsheets were affixed on A4 paper, and adjacent color patches were printed twice on the handsheets using a Bizhub PRESS C6000 electrostatic printer (Konica Minolta, Tokyo, Japan). The whitening, or overprinting, distance between the colors patches was measured, which was the overprint accuracy. RESULTS AND DISCUSSION Effect of Beating on the Ink Absorption Beating is an important step in papermaking. Beating resulted in swelling, fibrillation, removal of primary layer and outer secondary layer. Correspondingly, the adsorption ability to ink was facilitated. On the other hand, beating could promote the binding of cellulose and further hinder the osmosis of ink. Table 1 shows the size distributions of pulp fibers, as measured by the fiber quality analyzer (FQA). The fiber length decreased from 1.221 mm to 1.116 mm when the beating degree was increased from 15 °SR to 40 °SR. Moreover, the width correspondingly decreased from 28.2 μm to 26.9 μm. During the beating process, the raw fibers were separated into several fibrillated fibers, which increased the surface area of the fibers and the number of hydroxyl groups. The hydrogen bonding among hydroxyl groups enhanced the bonding forces among the fibers. Table 1. Effect of Beating Degree on Fiber Morphology Beating Revoluti ons (r)

Beating Degree (°SR)

5000 10000 12500 15000

15 26 33 40

Fiber Mean Length (mm) LengthWeightArithmetic weighted weighted Length Length Length 1.221 2.085 2.665 1.165 1.894 2.624 1.313 1.875 2.609 1.116 1.846 2.589

Fines Content (%) Width (μm) 28.2 27.6 27.3 26.9

Arithmetic Length

Lengthweighted

41.3 43.2 43.8 44.5

10.4 9.7 9.4 9.1

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Fig. 1. (A) The capillary structure sizes of the paper surfaces; (B) the ink mark lengths of different papers

A two-step process was employed in printing, involving pressing the ink into the voids on the surface of the paper and the subsequent penetration of the ink into the voids by capillary absorption. As shown in Fig. 1B, beating remarkably reduced the ink absorption of both softwood paper and hardwood paper. The ink absorption performance of the hardwood paper was better than that of the softwood paper, which was mainly attributed to the short and narrow fibers of hardwood pulp. Many capillary structures and high surface smoothness resulted from the paper preparation to improve the spreading, adhesion, and penetration of ink. Furthermore, the ink absorption of the paper was closely related to the gap size between fibers. The gap sizes of papers with different beating speeds were measured with a polarizing microscope, as shown in Fig. 1A. The prepared paper with a beating revolution value of 5000 revs showed a void distribution of 120 μm to 165 μm between fibers. These large voids allowed the ink to penetrate into the papers and caused a short ink mark length of 3.5 cm, indicating excellent ink absorption. With increased beating speed, the space between the fibers decreased to a range from 50 μm to Dong et al. (2020). “Ink absorption and overprint,” BioResources 15(1), 1397-1406.

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85 μm. The ink mark length increased to 5.1 cm due to decreased ink penetration. In contrast, beating displayed a limited effect on the ink absorbability of hardwood paper, revealed by a slight decrease of void size from 70 μm to 90 um to 55 μm to 70 um when the beating revolutions increased from 5000 to 15000 revs. One possible explanation for this result was that the fiber distribution, with small surface voids, was relatively uniform for the shorter hardwood fibers. Effect of Different Pulps on the Ink Absorption The types and sizes of the fibers affected the ink absorption of the paper. The effect of different pulps, softwood pulp and hardwood pulp, on the ink absorption of the prepared papers is shown in Fig. 2.

Fig. 2. The ink marks of different pulp papers

Figure 2 shows the changes of ink mark length for different papers prepared with various softwood pulp contents. The ink mark length first increased rapidly from 4.8 cm to 5.9 cm with the increase in softwood pulp content, and then it plateaued at 50% softwood pulp content (reaching a maximum length of 5.9 cm), and subsequently decreased to 4.3 cm. Generally, the fibers in softwood pulp are longer than those in hardwood pulp. Meanwhile, the high crystallinity index of softwood fibers hindered ink penetration and absorption into the paper. In contrast, the fibers in hardwood pulp are generally shorter and weak, which resulted in good ink absorbability. When the softwood pulp and the hardwood pulp were mixed together, particularly with each at 50% content, the prepared papers had longer ink mark lengths (i.e., low ink absorption). A possible reason for this result was that the fine fibers filled the network structure from long fibers stacking of softwood pulp to form a smooth and compact surface. Therefore, the ink penetration into the paper was hindered, resulting in low ink absorption. As the softwood pulp content was decreased to 0% (pure hardwood pulp), the smooth surface with large specific surface area and excellent liquid absorption for the obtained papers facilitated the adhesion and spreading of the ink. This led to high ink absorption (with a short ink mark length of 4.3 cm).

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Effect of Sizing on the Ink Absorption The purpose of paper sizing is to increase its hydrophobic performance, so the softwood paper can resist liquid. The effects of sizing with an AKD dosage of 0.1% on the ink absorption were also investigated.

Fig. 3. Comparison of ink mark lengths on softwood paper for sizing

As shown in Fig. 3, the sizing decreased the ink absorption of the paper (the short ink mark length). For the paper with a beating number of 5000 revs, an ink mark length of 4.15 cm was observed after sizing, which was 0.65 cm longer than that without sizing. Under the weak beating, the sizing agent was evenly distributed and firmly adhered on the rough surfaces of long fibers. Its filling effects efficiently hindered the ink’s entrance into the voids on the paper surface, thus reducing the ink absorption of the paper. When the beating number increased to 15000 revs, the sizing exhibited a more effect on reducing ink absorption. The ink mark length of 5.1 cm before sizing was markedly lengthened to 6 cm after sizing, which was mainly attributed to the micro-fibrillation of fibers under high beating speed and adequate filling of voids by sizing agents. The results indicated that the sizing can inhibit ink absorption of paper, especially for that with a high beating speed. Effect of Basis Weight on the Ink Absorption Basis weight has important effects on the printing adaptabilities of paper, such as tensile strength, folding strength, and tearing strength. Increasing the basis weight will increase the opacity and color contrast of paper, thus improving the quality of printed matter. Figure 4 displays the effect of the basis weight on the ink absorption of the paper.

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Fig. 4. The effect of basis weight on the ink mark length

As shown in Fig. 4, the ink absorptions of the softwood and hardwood papers slightly decreased with increasing basis weight, as revealed by the increasing ink marks length. When the basis weight varied from 60 g/m2 to 100 g/m2, the corresponding ink mark lengths for the softwood and hardwood papers changed, respectively, from 4.7 cm and 4.4 cm to 5.1 cm and 4.8 cm. Because the increased basis weight only facilitated the deposition of pulp fibers in the Z-direction of the paper, which has no effect on the fibers and internal structure of the paper, only a slight increase in ink mark length was detected. Meanwhile, the longer fibers tend to sink first and crosslink to form the lower layer of paper on the molded net during paper formation and dewatering. The fine fibers fall into the gaps on the surface of the wet web of paper due to their minimal size. The size of the void structure was effectively reduced, which thus resulted in the low ink absorption of the paper. Effect of Different Basis Weights on the Accuracy of Overprinting The surface compressibility of paper, one of the important factors affecting the clarity of the printing patterns and the accuracy of overprinting, determines the contact degree between the paper surface and the inking rubber at the moment of embossing. The basis weight significantly affects its surface compressibility, which in turn determines the accuracy of overprinting and finally reflects the quality of printing products. The basis weight of a paper can directly reflect its compressibility, which is responsible for the printing smoothness of a paper under the action of printing pressure. Especially during the first printing, the thickness of the paper was compressed by the printing pressure and partially rebounded after the cessation of the pressure. Therefore, the registration deviation always appeared during the subsequent overprinting because of the contact difference between two printings. When the basis weight of the paper was relatively low, the printing pressure caused a low compression deformation of the paper, due to the strong resilience of thin paper. As a result, the overprint had a relatively small error.

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Fig. 5. Influence on overprint precision of different basis weights

As shown in Fig. 5, a negligible overprinting error of 0.1 mm to 0.2 mm was observed for the paper with a basis weight of 60 g/m2 to 70 g/m2, which resulted in greater precision and accuracy of overprint. As the basis weight increased to 90 g/m 2, the overprinting error also increased, reaching to 0.72 mm. The increase was mainly attributed to the remarkable compression deformation and poor resilience during the overprinting process with the thickness increase of the paper in Z-direction. When the thickness could not be restored to the initial size under the action of rebound, a larger overprinting error occurred. Moreover, the overprinting error was related to the papermaking materials. The papers from hardwood exhibited superior performance in the overprinting (low overprint deviation), compared with that of softwood. The main reason for this result was that the hardwood contained more long and narrow micro-fibers. Therefore, the paper from hardwood had better printing performance and greater overprint accuracy. CONCLUSIONS 1. Compare to paper made from softwood, paper made from hardwood exhibited superior properties for the ink absorption capacity and overprinting precision, which was attributed to a greater content of fine fibers. 2. After beating, the void structure of the obtained paper became denser, resulting in decreased ink absorption capacity. 3. The increase of basis weight had a negligible effect on the ink absorption capacity.

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ACKNOWLEDGMENTS The authors are grateful for financial support from the Natural Science Foundation of Shandong Province (ZR2017MC007), R&D Focus of Shandong Province (2017GGX80102), International Cooperation Funding of Qilu University of Technology (QLUTGJHZ2018030; QLUTGJHZ2018027), and Jiangsu Provincial Key Laboratory of Pulp and Paper Science and Technology(KL201906; KL201905). REFERENCES CITED Chinga-Carrasco, G. (2009). “Exploring the multi-scale structure of printing paper – A review of modern technology,” Journal of Microscopy 234(3), 211-242. DOI: 10.1111/j.1365-2818.2009.03164.x Enomae, T., Dogome, K., and Isogai, A. (2012). “Evaluation of absorption of microdroplets on paper for creation of paper-based microstructures,” Journal of Materials Science 47(8), 3554-3563. DOI: 10.1007/s10853-011-6201-5 Havlínová, B., Cicák, V., Brezová, V., and Horňáková, L. (1999). “Water-reducible flexographic printing inks – Rheological behaviour and interaction with paper substrates,” Journal of Materials Science 34(9), 2081-2088. DOI: 10.1023/A: 1004511826583 Heard, P. J., Preston, J. S., Parsons, D. J., Cox, J., and Allen, G. C. (2004). “Visualisation of the distribution of ink components in printed coated paper using focused ion beam techniques,” Colloids and Surfaces A: Physicochemical and Engineering Aspects 244(1-3), 67-71. DOI: 10.1016/j.colsurfa.2004.05.012 Jiang, B., Huang, Y. D., and Bai, Y. P. (2011). “Noncontact and rapid analysis of the quality of the recording coating on ink jet printing by near-infrared spectroscopy,” Analyst 136(24), 5157-5161. DOI: 10.1039/c1an15676d Kim, H., Choi, J. H., Park, Y. W., Park, T. H., Song, E. H., Shin, S. J., Lee, H. J., and Ju, B. K. (2012). “P-54: Contact printing technologies for encapsulation of flexible OLEDs,” SID Symposium Digest of Technical Papers 43(1), 1258-1260. DOI: 10.1002/j.2168-0159.2012.tb06027.x Kwon, K.-S., and Kim, W. (2007). “A waveform design method for high-speed inkjet printing based on self-sensing measurement,” Sensors and Actuators A: Physical 140(1), 75-83. DOI: 10.1016/j.sna.2007.06.010 Li, Y., and He, B. H. (2011). “Investigation into the coating surface topography and properties of paper related to drying condition,” Advanced Materials Research 233235, 1614-1618. DOI: 10.4028/www.scientific.net/AMR.233-235.1614 Li Xia. (2011). “Effect of paper surface properties on print quality,” Heilongjiang Paper 2011(01), 41-43. DOI: CNKI:SUN:HLZZ.0.2011-01-014 Ngo, S., Lowe, C., Lewis, O., and Greenfield, D. (2017). “Development and optimisation of focused ion beam/scanning electron microscopy as a technique to investigate cross-sections of organic coatings,” Progress in Organic Coatings 106, 33-40. DOI: 10.1016/j.porgcoat.2017.02.003 Ozaki, Y. (2011). “Application of confocal laser scanning microscopy (CLSM) for observing adhesives in paper,” Journal of Adhesion Science and Technology 25(6-7), 723-741. DOI: 10.1163/016942410X525902 Pjanic, P., and Hersch, R. D. (2015). “Color changing effects with anisotropic halftone Dong et al. (2020). “Ink absorption and overprint,” BioResources 15(1), 1397-1406.

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prints on metal,” ACM Transactions on Graphics 34(6). DOI: 10.1145/2816795.2818083 Reme, P. A., and Helle, T. (2002). “Assessment of transverse dimensions of wood tracheids using SEM and image analysis,” Holz als Roh- und Werkstoff 60(4), 277282. DOI: 10.1007/s00107-002-0310-4 Sodhi, R. N. S., Sun, L., Sain, M., and Farnood, R. (2008). “Analysis of ink/coating penetration on paper surfaces by time-of-flight secondary ion mass spectrometry (ToF-SIMS) in conjunction with principal component analysis (PCA),” Journal of Adhesion 84(3), 277-292. DOI: 10.1080/00218460801954474 Yan, D., and Li, K. (2008). “Measurement of wet fiber flexibility by confocal laser scanning microscopy,” Journal of Materials Science 43(8), 2869-2878. DOI: 10.1007/s10853-007-2085-9 Article submitted: September 8, 2019; Peer review completed: November 23, 2019; Revised version received: November 21, 2019; Accepted: November 22, 2019; Published: January 8, 2020. DOI: 10.15376/biores.15.1.1397-1406

Dong et al. (2020). “Ink absorption and overprint,” BioResources 15(1), 1397-1406.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Early failure detection of paper manufacturing machinery using nearest neighbor-based feature extraction Wonjae Lee (1), Kangwon Seo (1,2) In a paper manufacturing system, it is substantially important to detect machine failure before it occurs and take necessary maintenance actions to prevent an unexpected breakdown of the system. Multiple sensor data collected from a machine provides useful information on the system’s health condition. However, it is hard to predict the system condition ahead of time due to the lack of clear ominous signs for future failures, a rare occurrence of failure events, and a wide range of sensor signals which might be correlated with each other. We present two versions of feature extraction techniques based on the nearest neighbor combined with machine learning algorithms to detect a failure of the paper manufacturing machinery earlier than its occurrence from the multistream system monitoring data. First, for each sensor stream, the time series data is transformed into the binary form by extracting the class label of the nearest neighbor. We feed these transformed features into the decision tree classifier for the failure classification. Second, expanding the idea, the relative distance to the local nearest neighbor has been measured, results in the real-valued feature, and the support vector machine is used as a classifier. Our proposed algorithms are applied to the dataset provided by Institute of Industrial and Systems Engineers 2019 data competition, and the results show better performance than other state-of-the-art machine learning techniques. Contact information: 1: Department of Industrial and Manufacturing Systems Engineering, University of Missouri, Columbia, Missouri; 2: Department of Statistics, University of Missouri, Columbia, Missouri. Engineering Reports. 2020;e12291. https://doi.org/10.1002/eng2.12291 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Article 4 – Maintenance

Received: 4 May 2020

Revised: 31 August 2020

Accepted: 1 September 2020

DOI: 10.1002/eng2.12291

RESEARCH ARTICLE

Early failure detection of paper manufacturing machinery using nearest neighbor-based feature extraction Wonjae Lee1

Kangwon Seo1,2

1 Department of Industrial and Manufacturing Systems Engineering, University of Missouri, Columbia, Missouri, 2

Department of Statistics, University of Missouri, Columbia, Missouri,

Abstract In a paper manufacturing system, it is substantially important to detect machine failure before it occurs and take necessary maintenance actions to prevent an unexpected breakdown of the system. Multiple sensor data collected from a machine provides useful information on the systemâ€™s health condition. How-

Correspondence Kangwon Seo, Department of Industrial and Manufacturing Systems Engineering, University of Missouri, E3437M Thomas & Nell Lafferre Hall, Columbia, MO 65211, USA. Email: seoka@missouri.edu

ever, it is hard to predict the system condition ahead of time due to the lack of clear ominous signs for future failures, a rare occurrence of failure events, and a wide range of sensor signals which might be correlated with each other. We present two versions of feature extraction techniques based on the nearest neighbor combined with machine learning algorithms to detect a failure of the paper manufacturing machinery earlier than its occurrence from the multistream system monitoring data. First, for each sensor stream, the time series data is transformed into the binary form by extracting the class label of the nearest neighbor. We feed these transformed features into the decision tree classifier for the failure classification. Second, expanding the idea, the relative distance to the local nearest neighbor has been measured, results in the real-valued feature, and the support vector machine is used as a classifier. Our proposed algorithms are applied to the dataset provided by Institute of Industrial and Systems Engineers 2019 data competition, and the results show better performance than other state-of-the-art machine learning techniques. KEYWORDS 1-nearest neighbor, feature extraction, multistream time series classification, rare event prediction, relative distance

INTRODUCTION

The pulp and paper production requires highly complex and integrated processes by chemical or mechanical means, which include wood preparation, pulping, chemical recovery, bleaching, and papermaking.1 In the advanced papermaking facilities, the systems are continuously monitored so that the operators can manage and control the processes, and detect any possible incidents that might cause an abrupt production break. To do this, a wide range of sensors are deployed in many different parts of manufacturing equipment to measure important process variables and monitor the system staThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ÂŠ 2020 The Authors. Engineering Reports published by John Wiley & Sons Ltd. Engineering Reports. 2020;e12291. https://doi.org/10.1002/eng2.12291

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tus. These sensors generate large amounts of multistream measurements. For instance, the motivating dataset for this research contains system monitoring measurements captured by 61 different sensors located in a paper manufacturing machinery.2 These raw measurements ought to be processed and analyzed appropriately to obtain useful information regarding the system’s health condition. The general purpose of this article is to develop a practical pipeline to process, analyze, and interpret the system monitoring data given as a form of the multistream time series (MSTS) to detect a system failure that may be occurred in the near future. One challenge problem that we aim to resolve through this project is that the machine failure has to be prognosed ahead of a physical occurrence. The traditional system monitoring tools such as the control chart-based quality control techniques focus on the detection of the assignable causes of the system abnormal status as soon after it occurs as possible. As such, the average run length has been used as the main performance metric for comparing various types of control charts.3 In the paper manufacturing process, however, once the machine failure occurs, the system instantly stops and there is no benefit to detect the failure afterward. Therefore, it is important to perceive any symptomatic signal followed by a machine breakdown even a few seconds earlier. To achieve this goal, we define our problem as a binary classification task where we aim to distinguish the precursory signs from the normal signals. This problem definition motivated us to use the terminology “MSTS” rather than “multivariate time series” as the multivariate data implies multiple responses in the statistical literature. Other difficulties for this task may be attributed to the multistream nature of the given data and a lack of failure-labeled observations. Although there exist several feature-based classification algorithms for the time series data, it is problematic to generate and select a proper set of features from high dimensional multistream data. As an alternative, the deep learning techniques are emerging as competent tools handling such data.4,5 However, these techniques require a substantially large amount of data, which is not the case for our problem where the dataset only includes 124 machine breakdown points among more than 18 000 time points where the labeled data points only consist of 0.67% among the whole dataset. Such an extremely imbalanced dataset makes it even harder to build a model with high performance since we don’t have enough labeled data to train the model. To solve the aforementioned problems, we rely on machine learning algorithms, which have been recognized as more powerful techniques for predictive tasks than traditional approaches that do not incorporate these techniques,5 with properly processed variables and informative features. Specifically, for each sensor or variable, we transform the time series instance into a scalar extracted from its nearest neighbor and feed the transformed variables into a proper off-the-shelf machine learning algorithms to make a classification. The nearest neighbor-based algorithm has been recognized as one of the most effective classification methods for time series data.6 In this article, we exploit the advantages of 1-nearest neighbor (1-NN) but extend the method for MSTS data. The objectives of these algorithms are to extract suitable features for MSTS classification. First, we extract the class label of the nearest neighbor only considering a single variable, which results in the binary features for each variable. Second, the relative distance to the nearest neighbor is measured, which is anticipated to provide more useful information on an instance’s nearest neighbor. In this research, we demonstrate how to predict the paper machine failure before it occurs (ie, early detection); and find the variables which have a significant effect on causing failures using these nearest neighbor-based features. The rest of this article is organized as follows. Section 2 reviews related work in time series classification. Section 3 shows the overall procedure to implement, and describes dataset, preprocessing, and two versions of algorithms we propose in this article. In Section 4, we evaluate the performance of the proposed algorithms with the real-world dataset of the paper manufacturing sensor signals. Finally, we conclude our research in Section 5.

RELATED WORK

A wide range of algorithms have been used and proposed to solve classification problems with univariate time series data. Sykacek and Roberts7 propose an approach with a latent feature representation by applying Bayesian theory to hierarchical time series processing. Esmael et al8 suggest a hybrid approach to improve the accuracy of the time series classifier with hidden Markov models. Jović et al9 examine the capability of four common decision tree ensembles in the biomedical time-series dataset. Eads et al10 employee a support vector machine (SVM) for time series classification with features extracted from the time series data. Cui et al11 demonstrate convolutional neural networks for time series classification problem to incorporate feature extraction and classification in a sin-

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gle framework. These algorithms have been employed as a single classifier or a combination of multiple methods, sometimes called an ensemble, to improve the performance of classification.12 Although the ensemble-based classifier is known as a prominent algorithm for time series classification tasks,13 it requires much computation for training, which may not be suitable for a large dataset. Meanwhile, Tan et al14 describe that the nearest neighbor classifier based on the Euclidean distance is a fast and promising classification algorithm when it comes to the big dataset. Recently, MSTS data has gained great attention, and many researchers have proposed new methods to solve the multistream-based problem. Orsenigo and Vercellis15 describe a classification method based on a temporal extension of discrete SVMs with the notions of warping distance and softened variable margin in the set of multivariate input sequences. Weng and Shen16 implement a new approach for MSTS classification. The eigenvectors of row-row and column-column covariance matrices of MSTS samples are calculated to extract features and a 1-NN classifier is used for the classification. The authors show that distance-based methods with 1-NNs are an effective way to classify MSTS. Other algorithms have also been used to deal with MSTS. Zhang et al17 address the challenges of MSTS data by presenting a real-time multiple profiles sensor-based process monitoring system. Feature extraction is considered as one of the popular techniques for MSTS classification. RodrĂguez and Alonso18 use the boosting algorithm to generate new features and a SVM is applied with these metafeatures. Kadous and Sammut19 seek to generate classifiers that are comprehensible and accurate with metafeatures. The authors describe applications of the sign language recognition and the electrocardiogram signal classification. Li et al20 suggest feature vector selection approaches for MSTS classification using singular value decomposition. Profile monitoring techniques with the use of the principal component analysis (PCA) method is another way to manage MSTS. Kim et al21 develop the method to detect profile changes of multistream tonnage signals for forging process monitoring and to classify fault patterns while Chang and Yadama22 propose a statistical process control framework to monitor nonlinear profiles to identify mean shifts in a profile with discrete wavelet transformation and B-splines. Paynabar et al23 suggest a multiway extension of the PCA technique to classify multistream profile data. Grasso et al24 suggest multiway PCA to deal with the reduction of data dimensionality and the fusion to all the sensor outputs. This article carries out two main multiway extensions of the traditional PCAs to handle MSTS. Deep learning has provided prominent results for this application with the popularity of the neural networks. Zheng et al25 propose a deep learning framework for MSTS classification using features extracted by a 1-NN with dynamic time warping (DTW). Karim et al4 utilize the long short-term memory fully convolutional network (LSTM-FCN) and attention LSTM-FCN for MSTS classification. Wang et al5 utilize a recurrent neural network and adaptive differential evolution algorithm for the same task. Despite the popularity of deep learning, this technique requires a high volume of dataset, and it is not suitable for our problem due to a lack of labeled data. An imbalanced classification problem where the distribution of class labels are severely skewed needs to be well managed due to the poor performance of learning algorithms in the presence of underrepresented data and severely skewed class distribution. This is because most algorithms assume that distributions of the dataset are balanced.26 The sampling methods which consist of oversampling and undersampling techniques are commonly used to improve classifier accuracy by providing a balanced distribution.27 The cost-sensitive method is an alternative for the imbalanced learning problem by using different cost matrices that outline the cost for misclassifying data instances.28 However, the failures in the paper machine occur so rarely that traditional techniques had difficulty in training models effectively. Active learning can be one of the most prominent methods which are applied to handle extremely imbalanced data. To deal with highly imbalanced classes, Attenberg et al29 propose guided learning which is an alternative technique where the agent inquires humans to find training examples representing the different classes. Kazerouni et al30 suggest an active learning algorithm to learn a binary classifier on a highly imbalanced dataset where most data has negative labels with a very small number of positive ones. Hybrid active learning is presented to leverage an explore-exploit trade-off to improve on margin sampling. Moreover, this active learning technique is combined with state-of-the-art deep learning techniques to improve performance. Fang et al31 reformulate active learning as a reinforcement learning problem where the policy plays a role in the active learning heuristic. An agent in the environment tries to find the data to be labeled in a validation set based on the deep Q-network. Haussmann et al,32 however, choose a deep Bayesian Neural Net for both a base predictor and the policy network to effectively incorporate the input distribution.

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MATERIALS AND METHODS

3.1

Dataset description

The dataset was provided by the Institute of Industrial and Systems Engineers (IISE) 2019 data competition, which recorded real sensor observations from a paper manufacturing process.2 Many different types of data are collected over a period of time using a variety of sensors located on the machines. Some sensors measure raw materials (eg, amount of pulp fiber, chemicals, and so on) and the others represent process variables (eg, blade type, couch vacuum, rotor speed, and so on). Overall, 61 different sensor signals are collected, and 1 month of monitoring data are recorded at every 2 minute for a paper manufacturing machine, which results in the dataset of 61 streaming signals at 18 398 time points. In addition, for each time point, the system condition (ie, normal or break) has been recorded in a binary response variable. Despite such a large number of measurements, the failures only occur at 124 time points (0.67% of total observations) during operation and this characteristic of the rare event makes it hard to predict the failure before it occurs. Table 1 summarizes the dataset. A data-driven approach is used for this problem instead of incorporating physical models since no information was given regarding sensor information and domain knowledge. Predicting failures for a pulp-and-paper mill is critical because a break has a significant impact on the entire process. Even though paper breaks rarely take place during operation, only one failure causes a significant loss of time and labor for identifying a cause of the failure and replacing any broken parts. Once the machine fails, the entire process should be stopped since the operation needs to be halted until the problem is found and fixed. This maintenance procedure would take more than an hour which would incur a substantial amount of cost. It indicates that only a small amount of failure reduction through early detection could give a significant amount of cost savings for industries.

3.2

Procedure

The overall procedure of the proposed algorithms in this article is presented in Figure 1 consisting of preprocessing, class label of the local nearest neighbor (CL-LNN) and relative distance of the local nearest neighbor (RD-LNN) with corresponding machine learning techniques. The original MSTS dataset is preprocessed before carrying out two types of feature extraction methods and these features are fed into a decision tree or SVM based on the extracted data types for early failure detection. More detailed information is described in the following sections.

3.3

Data preprocessing

The MSTS data obtained from the paper manufacturing machinery is given as ⎛ s1,1 ⎜ ⎜ s2,1 MSTS = (s1 s2 … sp c) = ⎜ ⎜ ⋮ ⎜s ⎝ T,1

s1,2

…

s1,p

s2,2

…

s2,p

⋮

sT,2

… sT,p

c1 ⎞ ⎟ c2 ⎟ ⎟ ⋮⎟ cT ,⎟⎠

(1)

where st, j ’s, t = 1, … , T, j = 1, … , p, are sensor signals measured at the time point t from the jth sensor, T = 18 274 is the number of measurement time points, p = 61 is the number of variables by different sensors, and ct ’s are records of the

T A B L E 1 Dataset Element Number of variables

Number of measurements

Value

Remark

Continuous variables

s1 ∼ s27 , s29 ∼ s60

Categorical variables

s28 (8 categories), s61 (2 categories)

Normal

18 274

Recorded by every 2 minute

Abnormal (failure)

124

description

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Dataset

Preprocessing Split dataset Training dataset

Test dataset

Standardization

Second derivative

Moving class label

Time Window Processing

1NN

LOO-CV Binary feature matrix )

Binary feature matrix )

binary

Calculate median, standard deviation

Relative Distance ( )

binary

Numerical feature matrix )

CL-LNN

Numerical value

Decision tree

Support Vector Machine

Trained Model

FIGURE 1

RD-LNN

Input Test data

Early failure detection

Training Model

Flow chart of the proposed method for early failure detection

system condition for each time point of measurement (ie, ct = 0 for normal, and ct = 1 for break). This sensor information is preprocessed to implement the classification algorithms. First, the entire data needs to be split into training and test dataset before data standardization is conducted for each variable since the test dataset should be unknown during the modeling. We divide the whole dataset into 90% for training and 10% for test dataset to do the experiments in Section 4 to apply the proposed algorithms in this article. Therefore, the training dataset is standardized first, and then the mean and SD from the training dataset is applied to the standardization of the test dataset. For implementing standardization, each measurement is scaled by subtracting the corresponding mean and then being divided by the SD so that the mean becomes 0 and the SD 1, as follows. st,j ←

st,j − mean(sj ) , std(sj )

j = 1, … , p,

(2)

where the notation ← indicates that the variable in the left-hand side is replaced with the new variable of the right-hand side, mean(sj ) and std(sj ) are the mean and SD, respectively, of the original measurement data from the jth sensor. Standardization is implemented to scale the data with mean 0 and SD 1 which usually gives better performance on the algorithm. The derivative then is applied to sense sudden changes in the sensor signals. The derivative in the time series is the difference between all neighboring points in one dimension. That is, s′t,j = |st,j − st−1,j |,

s′′t,j = |s′t,j − s′t−1,j |,

j = 1, … , p,

(3)

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0 0 0 0 0 0 0 0 0 1 0 0 0

FIGURE 2

Early detection by moving column c by 1 row

Time window

0 0 0 0 0 0 0 0 0 0 1 0 0

where st, j′ and st, j′′ represent the first and second derivatives of st, j , respectively. The first derivative is related to a gradual change in time series which may not be sensitive to a sudden machine breakdown, while the second derivative is more useful to detect sharp changes that appeared in the streaming signals. For the rest of this article, we use the second derivative to seize precursors of immediate failure. In this project, we aim to detect the failure earlier before it occurs. One simple way to achieve this goal is to use the class label of k time points ahead for the current instance’s class label so that classifiers are able to learn to predict ct + k the system condition at k time units ahead.2 ct ← ct+k , where k = 1, 2, … .

(4)

We set k = 1, which implies that we build a model to detect a failure 2 minutes earlier than its occurrence. Figure 2 depicts this process. In classification problems with streaming data, temporal sequence data can normally secure more information compared with the data point sampled at a single time step.33 Accordingly, we extract small fragments of sequences by conducting, namely, time window processing. For a given window size m, a window instance consists of the last m sensor measurements up to time t which corresponds to the rows of MSTS data given in Equation (1) with time indices t − m + 1, … , t. The class label of the window instance is given as ct so that it represents the system condition at the last time point of the window. These window instances provide features to be used in a machine learning algorithm. In addition, we address the problem of severely imbalanced class labels of the original MSTS data while constructing the window instances by making a balance between two labels to some extent. That is, for time window processing we select all the time points t where ct = 1 and only randomly select t where ct = 0 such that it makes difference between the number of class labels not too large. The constructed window instances and those class labels are given as the following form. ⎛w′ ⎜ 1,1 ⎜w′ (W y) = ⎜ 2,1 ⎜ ⋮ ⎜ ′ ⎝wn,1

w′1,2

…

w′1,p

w′2,2

…

w′2,p

⋮

w′n,2

… w′n,p

y1 ⎞ ⎟ y2 ⎟ ⎟, ⋮⎟ ⎟ yn ⎠

(5)

where each row represents each window instance. That is, wi, j is the sequence of length m which is the second derivatives of the jth sensor signals, and yi is the class label of the ith window instance. Note that the row index i = 1, … , n merely distinguishes each window instance, not necessarily implies the time point. The time window processed training dataset (Wtrain ytrain ) and test dataset (Wtest ) are used as input of Algorithms 1 and 2, respectively.

3.4

1-NN for time series classification

In the field of data mining and machine learning, one of the most frequently studied problems is classification.34 The classification process is to evaluate the similarities in a dataset to classify them into designated classes. One of the differences

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between time series classification problems and traditional classification problems is that the attributes are arranged in order and input features may be correlated. The 1-NN is a popular classifier for the time series classification as its performance can compete with the most complex classifiers.6 When a new observed time series instance comes out, the 1-NN classifier looks for the instance in the training dataset which has the shortest distance with the new instance and predicts the class of the new instance as the class label of the closest instance. A distance measure such as the Euclidean distance is used to compare two-time series instances. For a one-dimensional time series data, the Euclidean distance between two-time series instances wi and wk is measured by √ √m √∑ DED (wi , wk ) = √ (wit − wkt )2 ,

(6)

t=1

where wi and wk are window instances with t = 1, … , m measurements to be compared each other. The other renowned distance measure for time series data is DTW, which is the method to find the optimal alignment between two time-dependent sequences. It has been widely used in the field of pattern recognition and broadly tested on the benchmark time series data. DTW is originally designed to compare different speech patterns for the purpose of automatic speech recognition to solve the problem of distortions in the time axis.35 It makes a time series stretched and realigned to better match the other time series.36 To find the DTW distance, the matrix M is built where the (t, t′ )th element of M is d(wit , wkt′ ) = (wit − wkt′ )2 . Then a warping path is defined as the monotonically increasing sequences of indices p = {(0, 0), … , (t, t′ ), … , (m, m)}. The DTW distance can be found by the warping path which has the minimum cumulative distance between two sequences. √ √H √∑ DDTW (wi , wk ) = min √ Mh , p

(7)

h=1

where H is the length of the warping path, Mh is the matrix element corresponding to the hth element of a warping path p.37 Figure 3 depicts how Euclidean matching and DTW matching compare similarities between two-time series instances. In brief, Euclidean distance measures the distance between the two waves regardless of the shapes, while the DTW measures the distance by taking into account the shapes of two sequences. However, due to its computational complexity of DTW, the distance measurement with the DTW may not be suitable to be applied for the real-time sensor streaming data in which it is required to find the nearest neighbor instance quickly.

F I G U R E 3 1-NN comparison between Euclidean and DTW matching. 1-NN, 1-nearest neighbor; DTW, dynamic time warping

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To select the appropriate distance measure between Euclidean distance and DTW distance, a separate experiment is conducted to compare the performance, of which the result is shown in Section 4. For our proposed algorithms, Euclidean distance is used to measure the distance between two-time series instances as the experiment shows that Euclidean distance requires much less time than DTW without a significant difference in performances between the two methods.

3.5

Nearest neighbor-based feature extraction

One possible way to extend the 1-NN for a single-stream time-series data to the case of multistream signals could be to use the sum of the Euclidean distance measured by Equation (6) for each variable to measure the similarity between two multistream window instances. In this case, however, information of all variables is aggregated, which results in the loss of each variable’s information and relationships between variables. Instead, we look for the nearest neighbor considering each variable only, which we call the localnearest neighbor (ie, the nearest neighbor in an embedded space of a single stream), and extract scalar features from it. These features are fed into different classification algorithms depending on the types of extracted features. Algorithm 1. CL-LNN feature extraction 1:

Input: Multistream window instances Wtrain for training, and Wtest for testing, class labels of training instances ytrain , index set of training data Train, index set of test data Test Output: Binary feature matrices Xtrain with elements xij , i ∈ Train, and Xtest with elements xij , i ∈ Test

3: 4: 5: 6: 7: 8: 9: 10: 11: 12: 13: 14:

for i ∈ Train do for j ∈ {1, … , p} dod∗ = L L is a large number used for a initialization for k ∈ Train ⧵ i dod = DED (xij , xkj ) for all instances in training data except itself (LOO-CV) if d ≤ d∗ thenk∗ ← k,d∗ ← d end if end forxij ← yk∗ store class label of the local nearest neighbor as a feature end for end for

15: 16: 17: 18: 19: 20: 21: 22: 23: 24: 25: 26:

for i ∈ Test do for j ∈ {1, … , p} dod∗ = L L is a large number used for a initialization for k ∈ Train dod = DED (xij , xkj ) for all instances in training data if d ≤ d∗ thenk∗ ← k,d∗ ← d end if end forxij ← yk∗ store class label of the local nearest neighbor as a feature end for end for

The first feature we propose is the CL-LNN, which is given as 0 or 1 for each variable. Algorithm 1 outlines the procedure of the CL-LNN feature extraction in which the MSTS data is converted into binary feature matrices Xtrain and Xtest . The local nearest neighbor is found by leave-one-out cross-validation (LOO-CV) for each variable on the training dataset Wtrain . That is, for an instance of the training dataset, LOO-CV searches all the other instances in the training dataset except itself and chooses the one that gives the highest matching with it, which is simple but effective for 1-NN.38

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Three different cases based on nearest neighbor-based feature extraction

On the other hand, for an instance of the test dataset, the algorithm simply searches the nearest neighbor from the training dataset. The nearest neighbor is found by computing Euclidean distance based on the time window for each variable as in Equation (6). Note that, for a given instance, the CL-LNN features for different variables may be varied because the nearest neighbor for each variable could be different. These binary features are fed into the decision tree classifier for the model training and prediction, which will be described in more detail in Section 3.6. The features can keep the original information of each sensor signal by considering each variable separately, and correlations between different variables are expected to be handled by the decision tree algorithm. Another feature we propose in this article is called the RD-LNN. While the CL-LNN can be thought of as features of hard classification where the outcome is certainly given as 0 or 1, RD-LNN provides features of soft classification, which can be seen as probability-like features. Although the binary feature extracted from the CL-LNN provides information on which one is the closest to the instance under consideration, it is not able to measure the degrees of significance or strength of the extracted feature. Let us consider three cases to classify the label of instances with nearest neighbor-based feature extraction in Figure 4. In the first case, there is a clear decision boundary which makes it easy to separate two distinct groups where CL-LNN might show superior performance. However, outliers in the second example make it more challenging to classify the target instance. Suppose we know the CL-LNN for a given instance is, say, 1 a break signal. To build a robust prediction model, we may also want to know how reliable and accurate this signal is. For the second case, even if the nearest neighbor is the break signal, this nearest neighbor is an outlier with respect to the majority of the other break signals. In this case, relying solely on the class label of the nearest neighbor may be risky. To complement this pitfall of binary features, we may consider measuring distances from the nearest neighbor to the other instances, respectively. If the distance value is large, the nearest neighbor is thought to be located far from the majority of its same class and does not provide reliable information. Whereas if the distance is small, the nearest neighbor is thought to represent the group of the same class and the information provided by this instance is more accurate. In lieu of direct distance measure, we use probability measure which is similar to the computation of P-value for a statistical hypothesis testing. Rare events (ie, breaks) in our dataset, however, appear to be indistinguishable from the other which is ambiguous to differentiate those two groups as in the third case. In this situation, we found that it is more effective to measure the relative distance for each group, respectively, instead of applying the same nearest neighbor to different groups. Specifically, given an instance of which the class label has to be predicted, Euclidean distances to all the other instances in the training dataset are computed. For each class label (y = 0, y = 1), the nearest neighbors are found. Let dâˆ—0 and dâˆ—1 be distances to nearest neighbors with class label 0 and 1, respectively. We can also find the approximated normal distribution for each class. Let X 0 and X 1 be random variables with these approximated normal distributions. The RD-LNN features are computed by P(X0 â‰¤ dâˆ—0 ) and P(X1 â‰¤ dâˆ—1 ) for each class, which can be interpreted as the probability that an observation is located farther than the nearest neighbor from the center of each class. That is, Pi = P(Xi â‰¤

dâˆ—i )

( =ÎŚ

dâˆ—i âˆ’ đ?œ‡i si

) ,

i = 0, 1,

(8)

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where ÎŚ is the cumulative distribution function of the standard normal random variable, đ?œ‡i and si are the median and SD of the distance between the target instance and all the training instance with the label i. The smaller RD-LNN is, the less likely the label to be found is reliable. Algorithm 2. RD-LNN feature extraction 1: Input: Multistream window instances Wtrain for training, and Wtest for testing, class labels of training instances ytrain , index set of training 2: 3: 4: 5: 6: 7: 8: 9: 10: 11: 12: 13: 14: 15: 16: 17: 18: 19: 20: 21: 22: 23: 24: 25: 26: 27: 28: 29: 30: 31: 32: 33: 34: 35: 36: 37: 38: 39: 40: 41: 42: 43: 44: 45: 46: 47: 48: 49:

data Train, index set of test data Test Output: Numeric feature matrices Xtrain with elements xij0 and xij1 , i âˆˆ Train, and Xtest with elements xij0 and xij1 , i âˆˆ Test for i âˆˆ Train do for j âˆˆ {1, â€Ś , p} dod0 = d1 = NULL initialize arrays to store distance values for k âˆˆ Train â§ľ i dod = DED (xij , xkj ) for all instances in training data except itself (LOO-CV) if yk = 0 then append d to d0 end if if yk â‰ 0 then append d to d1 end if end for extract features from distances with label 0 dâˆ—0 â†? min(d0 ) distance to the nearest neighbor with label 0 q0 â†? interquartile(d0 ) đ?œ‡0 â†? median(q0 ), s0 â†? stdev(q0 ) xij0 â†? P(X â‰¤ dâˆ—0 ), where X âˆź N(đ?œ‡0 , s20 ) extract features from distances with label 1 dâˆ—1 â†? min(d1 ) distance to the nearest neighbor with label 1 q1 â†? interquartile(d1 ) đ?œ‡1 â†? median(q1 ), s1 â†? stdev(q1 )xij1 â†? P(X â‰¤ dâˆ—1 ), where X âˆź N(đ?œ‡1 , s21 ) end for end for for i âˆˆ Test do for j âˆˆ {1, â€Ś , p} dod0 = d1 = NULL initialize arrays to store distance values for k âˆˆ Train dod = DED (xij , xkj ) for all instances in training data except itself (LOO-CV) if yk = 0 then append d to d0 end if if yk â‰ 0 then append d to d1 end if end for extract features from distances with label 0 dâˆ—0 â†? min(d0 ) distance to the nearest neighbor with label 0 q0 â†? interquartile(d0 ) đ?œ‡0 â†? median(q0 ), s0 â†? stdev(q0 ) xij0 â†? P(X â‰¤ dâˆ—0 ), where X âˆź N(đ?œ‡0 , s20 ) extract features from distances with label 1 dâˆ—1 â†? min(d1 ) distance to the nearest neighbor with label 1 q1 â†? interquartile(d1 ) đ?œ‡1 â†? median(q1 ), s1 â†? stdev(q1 ) xij1 â†? P(X â‰¤ dâˆ—1 ), where X âˆź N(đ?œ‡1 , s21 ) end for end for

Algorithm 2 describes the procedure in which the algorithm generates the numerical values by measuring the probability representing the relative position of the nearest neighbor for each class compared with the other instances with the same class label. We found that this unique feature extraction technique improves the performance of classification

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when these extracted features from RD-LNN are fed into SVM. Note that two features are extracted from each variable corresponds to each class label (y = 0, y = 1). The normal distribution is approximated to distance data where the mean and SD are set as the sample median and the SD of distances included in the interquartile range (ie, data ranging from the first quartile Q1 to the third quartile Q3) to minimize the effect of outliers.

3.6

Training model

Different machine learning techniques are used for CL-LNN and RD-LNN, respectively, to train the model and predict failures 2 minutes earlier based on the data type that algorithms produce. First, the C5.0 decision tree algorithm which is an improved version of its predecessor C4.5 is applied to the CL-LNN algorithm for the classification between normal and abnormal conditions. In order to improve model performance, we implemented adaptive boosting which is the process in which many trees are built and trees vote for the best class. We set boosting iterations to 10. A cost matrix is also employed by assigning a penalty to different types of errors to improve the accuracy where 1 is assigned for the false positive, and 5 is chosen for the false-negative since failing to detect breaks can be a more expensive mistake. Second, the numerical feature matrix (Xtrain ) from the training dataset (Wtrain ) is fed into SVM to generate the model, and the other matrix (Xtest ) is used to evaluate the performance of the model generated with training dataset (Wtest ) from RD-LNN. To train SVM model, the function of kernel which takes data as input and transforms it into the required form for training and predicting is chosen to be radial. The cost is assigned to 1 to trade off the correct classification of training examples against maximization of the decision functionâ€™s margin. 0.5 is also used for gamma parameter which defines how far the influence of a single training example reaches. These parameters are selected heuristically by experiments based on our dataset.

4 4.1

RESULTS OF EXPERIMENT Performance analysis

We compare our methods with four other different approaches which include a type of artificial neural network and general machine learning models without the feature extraction technique we proposed in this article. The first method is an Autoencoder which is comprised of encoder and decoder for extremely rare event classification1 . The encoder is to learn the features of input data which are normally in a reduced dimension, while decoder regenerates the original data from the encoder output. This method uses a dense layer Autoencoder which selects the instances in random without considering the correlation among instances. The second approach is the improved version of the first one by constructing LSTM (long short-term memory) Autoencoder which contemplates the temporal features2 . Both methods also attempt to detect failures 2 minutes earlier with the same dataset we use in this article. We, in addition, compare the method without feature extraction technique (ie, decision tree without CL-LNN, SVM without RD-LNN) in order to show the benefit of the proposed algorithm. Table 2 shows the prediction result in the form of a confusion matrix to compare the performance of six methods. As we can see from these results, it looks like all six methods are comparable, and hard to find which method provides better performance. It also shows the trade-off between the true positive/negative and false positive/negative. RD-LNN, however, shows the lower number of false-positive among the four methods. Table 3 provides other metrics to compare the performance among six different methods. In the table, four metrics are used to evaluate the performance of the proposed classification algorithms. Precision (also known as the positive predictive value) is defined as the proportion of positive instances over the total number of positive. Recall (also known as sensitivity, true positive rate) is the number of true positives divided by the number of true positives plus the number of false negatives. In addition, False positive rate (1 - specificity) refers to the probability of falsely rejecting the null hypothesis for a particular test. Since, however, the distribution of class labels is highly skewed, another performance metric F-measure has been 1

The implementation of Autoencoder refers to this site (https://github.com/cran2367/autoencoder_classifier/blob/master/autoencoder_classifier. ipynb) 2 The implementation of LSTM Autoencoder refers to this site (https://github.com/cran2367/lstm_autoencoder_classifier/blob/master/lstm_ autoencoder_classifier.ipynb)

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T A B L E 2 Confusion

LSTM Autoencoder autoencoder Decision tree SVM Prediction 0

CL-LNN RD-LNN Remark 1

2726 22

3355 19

1636 19

1769 24 1514 19 1762 22

TN FN

173

272

179

FP TP

282

matrix

Abbreviations: CL-LNN, class label of the local nearest neighbor; LSTM, long short-term memory; RD-LNN, relative distance of the local nearest neighbor; SVM, support vector machine.

Item

Autoencoder

LSTM autoencoder

Decision tree

SVM

CL-LNN

RD-LNN

Precision

0.017

0.029

0.032

0.021

0.081

True positive rate

0.120

0.296

0.240

0.040

0.240

0.120

False positive rate

0.060

0.075

0.099

0.024

0.157

0.019

F-measure

0.030

0.052

0.057

0.028

0.038

0.097

T A B L E 3 Performance with four metrics

Note: The boldfaced value implies the highest performance for each measure. Abbreviations: CL-LNN, class label of the local nearest neighbor; LSTM, long short-term memory; RD-LNN, relative distance of the local nearest neighbor; SVM, support vector machine.

used to measure the performance of a rare classification problem. F-measure (also sometimes called the F1 score or F-score) is the combination of precision and recall using the harmonic mean, a type of average being used for rates of change. Based on the table, RD-LNN shows the best performance in precision, false-positive rate, and F-measure among six methods while LSTM autoencoder only performs better in a true positive rate. Note that RD-LNN shows outstanding performance compared with the others in F-measure which are well suited to represent the performance of the highly imbalanced dataset. Another metric used to measure the performance is a receiver operating characteristic curve, or ROC curve, which represents the diagnostic ability of a binary classifier. This tool is suitable to visualize and compare the performance of our proposed algorithms. The true positive rate (TPR or sensitivity) is plotted in the ROC curve against the false positive rate (FPR or 1 - specificity) at different threshold settings to exhibit how much a model is able to distinguish classes. In Figure 5, ROC curves of six different methods are plotted to compare the performance using area under the ROC curve (AUC) which represents the degree of separability. LSTM-Autoencoder which considers temporal features show better performance than Autoencoder and the AUC of RD-LNN is higher than the one of CL-LNN by considering the relative distance to detect the failures. Decision tree and SVM which are not adopting the feature extraction we proposed also provide a lower performance than RD-LNN. Overall, the AUC of RD-LNN shows the largest value 0.724, and we reach to the same conclusion that the performance of RD-LNN is better than any other five methods. Figure 6 summarizes performance comparison based on F-measure and AUC. LSTM-autoencoder and RD-LNN appear to be better than the others in AUC, while RD-LNN is the only one to show the outstanding performance in F-measure. Additional experiment is conducted separately to choose distance measure algorithm between Euclidean distance and DTW distance considering that 1-NN method requires demanding calculation of distance between the target data point and all the points in the training set. In the experiment comparing two methods to measure the distance in Table 4, we found that DTW distance spends much more time to complete the same task than Euclidean distance which takes only about 4.6 minutes while it shows the almost same performance. The reason why Euclidean distance performs well compared with DTW in this experiment is that DTW distance is particularly well suited for the application of automatic speech recognition in which speaking speeds vary based on time. However, time-series data that has been used here has the same time difference.

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AUC =

0.2

0.4

0.6

0.8

1.0

0.0

0.2

Decision Tree

SVM

0.8

1.0

0.8 0.6 0.4

True Positive Rate

AUC =

0.2

1.0 0.8 0.6 0.4 0.2

0.378

0.0

0.594

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

CL−LNN

RD−LNN

1.0

0.4

AUC = 0.724

0.0

0.601

0.8

False Positive Rate

True Positive Rate

False Positive Rate

0.8

0.2

AUC =

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

False Positive Rate

4.2

0.6

False Positive Rate

AUC =

0.0

FIGURE 5

0.4

False Positive Rate

0.0

True Positive Rate

0.715

1.0

0.0

True Positive Rate

AUC =

0.0

0.694

0.4

0.8

True Positive Rate

LSTM−Autoencoder

0.0

True Positive Rate

Autoencoder

0.4

0.6

0.8

1.0

False Positive Rate

ROC curves of six different methods. ROC, receiver operating characteristic

Effects of window size and the number of normal instances

In this subsection, the key parameters which highly influence the performance of RD-LNN are examined. First, the window size m = 20 was determined based on the experiment considering F-measure as well as running time which is also an important factor when it is deployed in the real-life application. Figure 7 represents how F-measure and running time3 are varied over window size m. F-measure shows the downward trend as the window size is increased while running time is increasing almost linearly due to the fact that lager window size demands more computation to estimate the distance. The relationship between F-measure and window size indicates that we need to find the optimal window size to capture the appropriate patterns that the failures might have. We substitute zero for F-measure when the algorithm is not able to detect the true failure 2 minutes earlier. It is noted that 20 window size shows good performance with decent computing burden, and it is used as the number of window sizes of the proposed algorithm in this article. 3 Running time can be varied based on computer performance. The computer specification used in this experiment: Windows 10 Pro, Intel Core i7, 16 GB RAM, 64-bit

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0.7

0.12 0.724

0.715

0.694

0.097

Performance comparison with AUC and F-measure. AUC, area under the ROC curve

0.1

0.601

0.594

0.6

FIGURE 6

0.08 0.5

0.378

0.057

0.4

0.06

0.052 0.3

0.038 0.03

0.2

0.04

0.028 0.02

0.1

0 Autoencoder

LSTM-Autoencoder

Decision Tree

SVM

AUC

CL-LNN

RD-LNN

F measure

Item

Euclidean distance

DTW distance

TN (True negative)

1514

1528

FN (False negative)

TP (True positive)

FP (False positive)

282

268

F-measure

0.038

0.040

AUC

0.601

0.618

Running time

4.6 minutes

5.13 hours

Remark

T A B L E 4 Comparison between Euclidean and DTW distance

Detect failures

(2 Ă— TP)/(2 Ă— TP + FP + FN)

Note: The boldfaced font was used to emphasize the difference of running time between two methods. (the other metrics are similar). Abbreviations: AUC, area under the ROC curve; DTW, dynamic time warping.

F I G U R E 7 The effect of the window size in RD-LNN for the training process. RD-LNN, relative distance of the local nearest neighbor

0.10 8

7 0.06

0.04

0.02

Running time (min)

F measure

0.08

5 0.00 20

100

Window Size

Another parameter we need to carefully determine is the number of normal instances randomly selected in the training dataset. We examined the effectiveness of the number of normal instances with the performance depicted in Figure 8. Note that 99 failures are included in the training dataset and the class distribution between failures and normal instances needs to be balanced to handle imbalanced dataset. It shows that F-measure increases when the number of normal instances for training increases from 100 to 200, and then significantly decreases after 200 while running time keeps rising over the number of normal instances. This indicates that 200 normal instances we randomly selected in the training dataset provide better performance than others.

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F I G U R E 8 The effect of the number of normal instances randomly selected in training data set

0.10 5.4

0.06 5.2 0.04 5.0

0.02

Running time (min)

F measure

0.08

0.00 100

150

200

250

300

No. of normal instances in training dataset

T A B L E 5 Root cause analysis through decision tree algorithm

4.3

Rank Variable Importance Rank Variable Importance Rank Variable Importance 1

100%

s41

62%

s20

100%

s39

58%

s21

100%

s37

58%

s32

100%

s35

49%

s10

s33

100%

s35

49%

s12

s40

100%

s34

46%

s13

81%

s30

44%

s24

s60

70%

s28

44%

s28

s15

65%

s27

40%

s29

s26

65%

s26

39%

s36

s57

64%

s21

38%

s42

s18

60%

s21

36%

s45

s31

59%

s18

34%

s49

s44

56%

s18

34%

s50

s14

49%

s18

32%

s52

s51

49%

s14

31%

s54

s37

46%

s14

31%

s55

s34

46%

s13

29%

s56

s11

45%

s12

29%

s58

s46

44%

s11

28%

s59

s61

Root cause analysis

Root cause analysis is implemented by measuring the importance of each variable to find the critical ones which cause the failure of paper manufacturing machinery based on the decision tree algorithm. The variable importance is estimated based on the percentage of training dataset samples that fall into all the terminal nodes after the split to find the root cause. In Table 5, 61 variables are listed in the order of importance from 1 to 61. Six variables (s3 , s20 , s21 , s32 , s33 , and s40 ) which have the importance 100% are the most important variables to detect failures earlier than its occurrence. In other words, these six variables have the most impact on the classification model. One interesting fact is that a categorical variable (s28 ) and a binary variable (s61 ) do not make any contributions to this model.

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T A B L E 6 Cost benefit analysis based on RD-LNN Item

Gain (by TPR)

Loss (by FPR)

Cost/occurrence

$10 000/True positive

$100/False positive

Assumed based on the relevant articles

Number of occurrence

124 × 12 month = 1488

(2 minutes × 30 × 24 hour × 365 day) − 1488 = 524 112

1 year

Occurrence Rate

Recall = 12.0%

FPR = 1.9%

Test result

Cost/year

$1 785 600

−$995 813

Total cost

$789 787

Remark

Abbreviations: BCs, boundary conditions; FPR, false positive rate; RD-LNN, relative distance of the local nearest neighbor; TPR, true positive rate.

The decision tree which consists of three types of nodes (ie, root nodes, decision nodes, and terminal (or leaf) nodes) and branches also shows similar results. As we can expect from variable importance, the most important variable is on the root node which is located on the top of the decision tree.

4.4

Cost benefit analysis

Based on the experiment, it suggests RD-LNN is able to detect three failures 2 minutes earlier among 25 paper breaks. In this section, we will analyze how much this proposed algorithm could make a contribution to the industries even though the performance does not look high enough to detect every failure before it occurs. Table 6 shows that even a small number of failure reduction improved by this algorithm can save a significant amount of cost for the industries every year. The gain is calculated based on the recall 12%, and the loss caused by the false alarm is estimated to find the total cost that we can save throughout a year. Ranjan et al2 imply that it will cost more than 10 000 dollars for a break. We assumed that failure would occur 124 times for 1 month based on our dataset. Since the classification algorithm can detect 12% of failure, almost 1.7 million dollars can be saved per year by preventing 179 possible failures. However, we also need to consider the other side, a negative effect caused by a false alarm which gives the warning even though the machine is in the normal state. We assumed that this false alarm would cost 100 dollars because people might stop working and need to check the machine status to find out the problem. Based on the fact that data is captured by every 2 minutes, 1488, the number of failures that occurred every year, is subtracted from the total number of failures. The total loss caused by false alarm would be less than 1 million dollars due to the FPR which is 1.9%. If both positive and negative factors are considered together to find the total cost, we can conclude that the algorithm we propose here can save more than 700 thousand dollars in total for a year.

D I S C U S S I O N A N D CO N C LU S I O N

It is crucial to detect the failure earlier to save cost and labor in a paper manufacturing facility. However, it is challenging to detect machine failure in advance due to the fact that data is comprised of MSTS and failures which rarely occur during operation without any clear symptom where we call extremely rare event problems. In this research, two types of methods called CL-LNN, RD-LNN are proposed based on the nearest neighbor to extract proper features for early detection of paper manufacturing machinery. The data is preprocessed with several different steps: splitting data, standardization, moving class label, second derivative, and time window processing. CL-LNN measures Euclidean distance to extract the class label of the nearest neighbor which will be fed into the decision tree classifier for the failure classification. Another algorithm called RD-LNN extracts relative distance-generating numerical values which are suitable to be trained with SVM. Experiments are implemented on the dataset provided by the IISE 2019 data competition to show the competitiveness of our proposed methods. Dataset is preprocessed and proposed algorithms are implemented with other machine learning techniques. Through the experiment, it finds that RD-LNN is able to extract features effectively to detect the abnormal condition in the MSTS dataset which would make a considerable contribution to industries by saving cost.

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Considering the fact that sensor measurements are collected every 2 minutes and it takes less than 20 seconds to analyze one measurement with our algorithm to detect a failure, this algorithm would be a feasible solution in a real-world environment where a prior warning is given so that technicians can take appropriate actions to prevent a breakdown. However, it would be possible to find a more efficient way to deal with computation complexity when deploying to a real-world environment. One possible solution for the real-time application is that, based on the fact that Euclidean distance is calculated based on squared differences between two instances at m time points (see Equation (6)), if we store these squared differences from, say, t = 1 to t = m, it can be easily updated, when a new signal is measured at t = m + 1, by dropping one at t = 1 and adding one at t = m + 1. In this case, by reutilizing previously computed results at t = 2, â€Ś , m, it is only required to compute one for t = m + 1 which will let us save much time to calculate the distance. It should also be noticed that the test dataset is standardized with mean and SD obtained from the training dataset since these parameters of the test dataset are not available during the model training. This fact could possibly lead to a negative impact on the performance if new measurements show a significant difference from the previous ones (training dataset). Although we assume that the future examples will have similar mean and SD as the training dataset in this article, this can be alleviated by updating those parameters as we gained the new measurements. Even though cost-benefit analysis shows promising results, further research to overcome the rare event situation is still necessary, since improving performance is limited by insufficient labeled data from which most of the machine learning algorithms normally suffer. More efforts should be made to overcome the lack of failure data which is normally encountered when collecting data in industries such as failures, spam email, fraud credit card transactions, and so on. The concept of active learning could provide a possible solution to handle the extremely rare event problem where the dataset is severely imbalanced (skewed) with a small number of initial training data available. The basic idea of active learning is that better performance in a machine learning algorithm can be achieved with fewer training labeled data if we are allowed to choose the data from which it learns. Therefore, we might be able to get better performance by adopting active learning algorithms in our future research. ACKNOWLEDGEMENT We are very grateful to the two anonymous reviewers and the Editor-in-Chief for their comments on the article. PEER REVIEW INFORMATION Engineering Reports thanks Giovanna Martinez Arellano and other anonymous reviewer(s) for their contribution to the peer review of this work. CONFLICT OF INTEREST The authors have no potential conflict of interest to declare. PEER REVIEW The peer review history for this article is available at https://publons.com/publon/10.1002/eng2.12291. DATA AVAILABILITY STATEMENT The data that support the findings of this study are openly available in arXiv.org at https://arxiv.org, reference number arXiv:1809.10717. ORCID Kangwon Seo

https://orcid.org/0000-0002-2128-4079

REFERENCES 1. Bajpai P. Basic Overview of Pulp and Paper Manufacturing Process. New York, NY: Springer; 2015:11-39. 2. Ranjan C, Mustonen M, Paynabar K, Pourak K. Dataset: rare event classification in multivariate time series; 2018. arXiv preprint arXiv:1809.10717. 3. Montgomery DC. Introduction to Statistical Quality Control. Hoboken, NJ: John Wiley & Sons; 2012. 4. Karim F, Majumdar S, Darabi H, Harford S. Multivariate lstm-fcns for time series classification. Neural Netw. 2019;116:237-245.

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5. Wang L, Wang Z, Liu S. An effective multivariate time series classification approach using echo state network and adaptive differential evolution algorithm. Exp Syst Appl. 2016;43:237-249. 6. Christ M, Kempa-Liehr AW, Feindt M. Distributed and parallel time series feature extraction for industrial big data applications; 2016. arXiv preprint arXiv:1610.07717. 7. Sykacek P, Roberts SJ. Bayesian time series classification. Advances in Neural Information Processing Systems, Vancouver, Canada in 2001. Cambridge, MA: MIT Press; 2002:937-944. 8. Esmael B, Arnaout A, Fruhwirth RK, Thonhauser G. Improving time series classification using Hidden Markov models. Paper presented at: Proceedings of the 2012 12th International Conference on Hybrid Intelligent Systems (HIS), Pune, India; 2012:502-507; IEEE. 9. Jović A, Brkić K, Bogunović N. Decision tree ensembles in biomedical time-series classification. Paper presented at: Proceedings of the Joint DAGM (German Association for Pattern Recognition) and OAGM Symposium; 2012:408-417; Springer, Berlin, Heidelberg. 10. Eads DR, Hill D, Davis S, et al. Genetic algorithms and support vector machines for time series classification. Applications and Science of Neural Networks, Fuzzy Systems, and Evolutionary Computation, Seattle, Washington. Vol 4787. Bellingham, Washington: SPIE; 2002:74-85. 11. Cui Z, Chen W, Chen Y. Multi-scale convolutional neural networks for time series classification; 2016. arXiv preprint arXiv:1603.06995. 12. Baesens B, Van Gestel T, Viaene S, Stepanova M, Suykens J, Vanthienen J. Benchmarking state-of-the-art classification algorithms for credit scoring. J Operat Res Soc. 2003;54(6):627-635. https://doi.org/10.1057/palgrave.jors.2601545. 13. Lines J, Taylor S, Bagnall A. Hive-cote: the hierarchical vote collective of transformation-based ensembles for time series classification. Paper presented at: Proceedings of the 2016 IEEE 16th International Conference on Data Mining (ICDM), Barcelona, Spain: 2016:1041-1046. 14. Tan CW, Petitjean F, WGI. FastEE: fast ensembles of elastic distances for time series classification. Data Mining Knowl Discov. 2020;34:231-272. https://doi.org/10.1007/s10618-019-00663-x. 15. Orsenigo C, Vercellis C. Combining discrete SVM and fixed cardinality warping distances for multivariate time series classification. Pattern Recognit. 2010;43(11):3787-3794. 16. Weng X, Shen J. Classification of multivariate time series using two-dimensional singular value decomposition. Knowl Based Syst. 2008;21(7):535-539. 17. Zhang C, Yan H, Lee S, Shi J. Multiple profiles sensor-based monitoring and anomaly detection. J Qual Technol. 2018;50(4):344-362. 18. Rodríguez JJ, Alonso CJ. Support Vector Machines of Interval-Based Features for Time Series Classification. New York, NY: Springer; 2004:244-257. 19. Kadous MW, Sammut C. Classification of multivariate time series and structured data using constructive induction. Mach Learn. 2005;58(2-3):179-216. 20. Li C, Khan L, Prabhakaran B. Feature Selection for Classification of Variable Length Multiattribute Motions. New York, NY: Springer; 2007:116-137. 21. Kim J, Huang Q, Shi J, and Chang T. Online Multichannel Forging Tonnage Monitoring and Fault Pattern Discrimination Using Principal Curve. ASME. J. Manuf. Sci. Eng. 2006;128(4):944-950. https://doi.org/10.1115/1.2193552. 22. Chang SI, Yadama S. Statistical process control for monitoring non-linear profiles using wavelet filtering and B-spline approximation. Int J Product Res. 2010;48(4):1049-1068. https://doi.org/10.1080/00207540802454799. 23. Paynabar K, Jin J, Pacella M. Analysis of multichannel nonlinear profiles using uncorrelated multilinear principal component analysis with applications in fault detection and diagnosis. IIE Trans. 2013;45(11):1235-1247. 24. Grasso M, Colosimo BM, Pacella M. Profile monitoring via sensor fusion: the use of PCA methods for multi-channel data. Int J Product Res. 2014;52(20):6110-6135. https://doi.org/10.1080/00207543.2014.916431. 25. Zheng Y, Liu Q, Chen E, Ge Y, Zhao JL. Time series classification using multi-channels deep convolutional neural networks. Paper presented at: Proceedings of the International Conference on Web-Age Information Management; 2014:298-310; Springer, Cham. 26. He H, Garcia EA. Learning from imbalanced data. IEEE Trans Knowl Data Eng. 2009;21(9):1263-1284. 27. Estabrooks A, Jo T, Japkowicz N. A multiple resampling method for learning from imbalanced data sets. Comput Intell. 2004;20(1): 18-36. 28. Ting KM. An instance-weighting method to induce cost-sensitive trees. IEEE Trans Knowl Data Eng. 2002;14(3):659-665. 29. Attenberg J, Provost F. Why label when you can search? Alternatives to active learning for applying human resources to build classification models under extreme class imbalance. Proceedings of the 16th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining; 2010:423-432. 30. Kazerouni A, Zhao Q, Xie J, Tata S, Najork M. Active learning for skewed data sets; 2020. arXiv preprint arXiv:2005.11442. 31. Fang M, Li Y, Cohn T. Learning how to active learn: a deep reinforcement learning approach; 2017; arXiv preprint arXiv:1708.02383. 32. Haussmann M, Hamprecht FA, Kandemir M. Deep active learning with adaptive acquisition; 2019. arXiv preprint arXiv:1906.11471. 33. Li X, Ding Q, Sun JQ. Remaining useful life estimation in prognostics using deep convolution neural networks. Reliab Eng Syst Safety. 2018;172:1-11. 34. Baradwaj BK, Pal S. Mining educational data to analyze students; 2012. arXiv preprint arXiv:1201.3417. 35. Srikanthan S, Kumar A, Gupta R. Implementing the dynamice warping algorithm in multithreaded environments for real time and unsupervised pattern discovery. Paper presented at: Proceedings of the 2011 2nd International Conference on Computer and Communication Technology (iccct-2011), Allahabad, India; 2011:394-398. 36. Sakoe H. Dynamic-programming approach to continuous speech recognition. Paper presented at: Proceedings International Congress of Acoustics; 1971; Budapest.

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How to cite this article: Lee W, Seo K. Early failure detection of paper manufacturing machinery using nearest neighbor-based feature extraction. Engineering Reports. 2020;e12291. https://doi.org/10.1002/eng2.12291

PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

UV/Vis Spectrometry-Based Analysis of Alkyl Ketene Dimer (AKD) Retention to Solve the Waxy Spot Problem in the Papermaking Process Kyong Ho Lee (1), Hye Jung Youn (2), and Hak Lae Lee (2). A sudden surge in the number of translucent and oval-shaped waxy spots caused a serious production loss of the papermaking process. The investigation of the spots revealed that the alkyl ketene dimer (AKD) sizing agent caused the waxy spot problem. A ultraviolet/visible (UV/vis) spectrometry method for the quantitative analysis of AKD was developed and used to reduce the waxy spot problem in paper products. The results showed that the method could be used to quantify AKD in both papermaking stock and white water. The major factors in the papermaking wet end that were associated with the waxy spot problem were evaluated, and practical approaches to solving the AKD retention problem and the waxy spot problem were proposed and implemented. The dosage of a retention aid was found to be the principal factor controlling AKD retention. However, varying the retention aid dosage resulted in the deterioration of the paper formation; therefore, this was not a suitable solution to the waxy spot problem. The type of fixing agent and AKD used was found to be the secondary factor affecting the AKD retention and papermaking system cleanliness. Mill trials were conducted on a paper machine to examine the effects of different fixing agents and AKD types on AKD retention and the waxy spot count at the reel. This approach identified a combination of fixing agent and AKD type that substantially improved AKD retention and reduced the formation of translucent waxy spots in the resulting paper products.. Contact information: 1: Hankuk Paper Manufacturing Co. Ltd., Ulsan 45010, South Korea; 2: Department of Forest Sciences, College of Agriculture & Life Sciences, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, South Korea; State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, People’s Republic of China. ACS Omega 2020, 5, 11227−11234 https://dx.doi.org/10.1021/acsomega.0c01374 This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

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UV/Vis Spectrometry-Based Analysis of Alkyl Ketene Dimer (AKD) Retention to Solve the Waxy Spot Problem in the Papermaking Process Kyong Ho Lee, Hye Jung Youn, and Hak Lae Lee*

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ABSTRACT: A sudden surge in the number of translucent and oval-shaped waxy spots caused a serious production loss of the papermaking process. The investigation of the spots revealed that the alkyl ketene dimer (AKD) sizing agent caused the waxy spot problem. A ultraviolet/visible (UV/vis) spectrometry method for the quantitative analysis of AKD was developed and used to reduce the waxy spot problem in paper products. The results showed that the method could be used to quantify AKD in both papermaking stock and white water. The major factors in the papermaking wet end that were associated with the waxy spot problem were evaluated, and practical approaches to solving the AKD retention problem and the waxy spot problem were proposed and implemented. The dosage of a retention aid was found to be the principal factor controlling AKD retention. However, varying the retention aid dosage resulted in the deterioration of the paper formation; therefore, this was not a suitable solution to the waxy spot problem. The type of fixing agent and AKD used was found to be the secondary factor affecting the AKD retention and papermaking system cleanliness. Mill trials were conducted on a paper machine to examine the effects of different fixing agents and AKD types on AKD retention and the waxy spot count at the reel. This approach identified a combination of fixing agent and AKD type that substantially improved AKD retention and reduced the formation of translucent waxy spots in the resulting paper products.

1. INTRODUCTION The hydrophilicity of the cellulose fiber that forms the basic structure of paper means that paper tends to be highly water absorbing. This limits the use of paper in many types of packaging, printing, and writing. To control the water absorption property of paper, various internal sizing agents have been developed. Alkyl ketene dimer (AKD), which was developed by Downey1 and introduced by Davis et al.,2 is one of the most widely used internal sizing agents for printing and writing grades of paper. AKD can be anchored to paper without the use of papermaking alum (aluminum sulfate) because it reacts with the hydroxyl group of cellulose to form ester bonds.3,4 However, the slow rate of this esterification reaction5−7 often causes problems that do not occur when conventional rosinbased sizing agents are used. Problems such as slippery paper8,9 and size reversion10,11 are attributable to AKD sizing. In addition to the slow reactivity of AKD with hydroxyl groups, AKD has been shown to react with water,12 resulting in a dialkylketone that has no or low internal sizing ability.6,13 In addition to having the above-described negative effects on paper properties, AKD also causes problems in the paper production stage. For instance, hydrolyzed AKD has been © 2020 American Chemical Society

reported to be the main cause of deposit formation in the papermaking process.14,15 Similarly, we have also observed a periodic pipe plugging problem at the final reject line of the screen system of a paper machine producing printing and writing grades of paper. A chemical analysis of the plugged material retrieved from the screen discharge line confirmed that AKD was the main cause of the plugging problem. Moreover, we also observed white granular deposits on the fabric of polydisk filters, which substantially decreased the filtration efficiency, and the chemical analysis showed that the white deposits were hydrolyzed AKD. These experiences showed us that it was crucial to manage AKD retention in our papermaking machine to ensure a clean production process. Specifically, when the retention level of AKD is low, it circulates through the short or long circulation lines, where it is exposed to high temperatures for a prolonged Received: March 26, 2020 Accepted: April 22, 2020 Published: May 6, 2020

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period of time and is thus hydrolyzed. Therefore, a retention analysis of AKD at the papermaking wet end was essential to determine how to better control the internal sizing of the final paper product and how to prevent AKD hydrolysis and subsequent deposit formation. Several quantitative or qualitative methods have been proposed for use in AKD retention analysis. For instance, Dart,16 Yano et al.,17 and Asakura et al.18 used a gas chromatography/mass spectroscopy (GC/MS) method to investigate the AKD retention determination. Similarly, Zule and Dolenc19 used solvent extraction and GC methods for AKD analysis. GC/MS is a good analytical tool, but it would be expensive for regular quantitative analysis in a paper mill. The use of radioactive AKD has been explored by Lindström and Söderberg6,7,20 and Lee and Luner.13 However, this method requires radioactively tagged AKD and is thus not applicable in the industrial context. Near-infrared (NIR) or infrared (IR) spectroscopy can be used for the qualitative analysis, but it is limited in its utility for the quantitative analysis of AKD.21,22 Jaycock and Roberts23 and Min and Shin24 confirmed that ultraviolet/visible (UV/vis) spectroscopy could be used for the qualitative and quantitative analyses of AKD. However, a more thorough investigation is required to determine its suitability for the AKD retention analysis. Furthermore, both the optimal retention level of AKD and the factors affecting the emulsion stability of AKD must be investigated to solve the abovedescribed problems associated with AKD use in papermaking processes. Accordingly, we have investigated a UV/vis spectrometrybased method for the quantitative analysis of AKD in the papermaking process and also used this for the AKD retention analysis. Based on this method, seven major factors in the papermaking wet end were evaluated to find the most practical methods to increase AKD retention and prevent the production of substandard paper products. These factors included retention aid dosage, fixing agent dosage, AKD type, fixing agent type, filler types, filler dosage, and pulp type. Finally, we carried out mill trials on a paper machine to determine the ability of the two most important factors that we had identified, i.e., the types of fixing agent and AKD, to enhance AKD retention and waxy spot reduction.

Article

Figure 1. Relationship between reaction time and UV/vis absorbance.

Figure 2. Relationship between DMAP/AKD ratio and UV/vis absorbance.

2. RESULTS AND DISCUSSION 2.1. Quantitative Analysis of AKD Retention Using UV/Vis Spectrometry. The effect of the reaction time between AKD and 4-dimethyl aminopyridine (DMAP) in chloroform solution was examined, while the ratio AKD/ DMAP was kept constant at 1:120. Figure 1 shows that there is a rapid reaction between AKD and DMAP at a constant 1:120 ratio of AKD/DMAP and that the reaction is complete after 90 min. Thus, 90 min was confirmed as the sufficient reaction time for AKD and DMAP. Next, varying the AKD/DMAP ratio with a constant reaction time of 120 min showed that the reaction progressed until the ratio was 120:1 (Figure 2). The next experiment showed that 10 min of extraction completed AKD extraction (Figure 3). The turbidity of AKD emulsion decreased rapidly as the extraction proceeded, indicating that the AKD emulsion was dissolved by the extraction solvent, resulting in complete solubilization within 30 min. Moreover, the data in Table 1 show that the presence of other stock components such as pulps and fillers had no

Figure 3. Relationship between extraction time and UV/vis absorbance.

Table 1. UV/Vis Absorbance (450 nm) of Various Extraction Conditions

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additional white water component

+AKD 100 ppm

+AKD 0%

Hw-BKP 0.1% BCTMP 0.1% GCC 0.1% PCC 0.1%

1.320 1.317 1.308 1.309 1.316

0.002 0.001 0.003 0.001

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Figure 4. UV/vis spectrum of AKD-I/DMAP reaction product (left) and calibration line for AKD-II (right).

influence on the AKD extraction by chloroform, indicating that AKD was completely extracted from the white water. The R2 values of the calibration lines (Figure 4) were >0.999, validating the suitability of this method for the AKD retention analysis. The absorbance at 338 nm was higher than that at 450 nm; however, the former absorbance was influenced by the presence of minor contaminants.23 Thus, the calibration line from the absorbance at 450 nm was used for analysis. 2.2. Effect of Papermaking Stocks on AKD Retention. The AKD retention effects of stocks prepared using hardwood bleached kraft pulp (BKP) 100%, hardwood BKP 50% + bleached chemithermomechanical pulp (BCTMP) 50% (L5B5), and BCTMP 100% were tested, and the results are shown in Table 2. Pulp type had a substantial effect on AKD

Table 3. Eﬀect of GCC and PCC Fillers on AKD Retention for Hw-BKP Stock AKD-I AKD-II

AKD-I AKD-II

retention (%) with HwBKP 50% + BCTMP 50%

retention (%) with BCTMP 100%

51.5 50.4

38.5 28.6

33.1 17.1

Hw-BKP + GCC

Hw-BKP + PCC

51.5 50.4

42.5 55.0

55.8 59.8

GCC fillers was lower than that of PCC when no retention aid was used, and this resulted in a reduction of AKD retention for the GCC stock. Many fine materials, such as fillers, sizing agents, and polymeric emulsions, are contained in a papermaking stock. As the particles of these fines are smaller than the opening of the papermaking fabric, their retention is quite low, especially on a high-speed paper machine. Consequently, these fines will drain out with white water and circulate through the white water circuit, unless they can be adsorbed onto long fiber surfaces or extensively flocculated to be retained on the wet web. To increase the retention of fines, a wide variety of retention systems are used. In this study, we used the Hydrocol retention system, which comprises a cationic poly(acrylamide) (PAM) and bentonite, and evaluated its effect on the retention of fines, including AKD. The relationship between the first-pass retention (FPR) and AKD retention is depicted in Figure 5.

Table 2. Eﬀect of Pulp Type on AKD Retention retention (%) with Hw-BKP 100%

Hw-BKP only

retention, with retention in the BKP stock being much higher than that in the BCTMP stock, while the L5B5 stock gave AKD retentions between those of the BKP and BCTMP stocks. When anionic AKD-II was used, the hardwood BKP and BCTMP stocks gave retentions of 50.4 and 17.1%, respectively, showing that anionic AKD was retained significantly less in the BCTMP stock. This was attributable to the fact that BCTMP is shorter in fiber length, contains more fines, and possesses more anionic charges. Fillers are widely used in papermaking, as they provide economic benefits and improve the printing and optical properties of paper.25 Fillers, however, also cause problems in the papermaking process and in paper properties. Fillers cause strength loss and linting on the printing press. Furthermore, fillers often cause a substantial reduction in sizing.26,27 A number of researchers have investigated the desizing effect of precipitated calcium carbonate (PCC) on AKD sizing.11,28 Table 3 shows the effects of different types of filler on the retention of AKD-I and AKD-II. A retention of 51.5% AKD-I was achieved when no filler was used, while the addition of ground calcium carbonate (GCC) and PCC led to 42.5 and 55.8% AKD-I retention, respectively. As AKD-I is positively charged, it was expected to be more adsorbed onto negatively charged GCC. Retention of anionically charged and small

Figure 5. Correlation of ﬁrst-pass retention in wet end and AKD retention in dynamic drainage analyzer (DDA) vacuum drainage.

The regression coefficient is 0.762, indicating a strong positive correlation between these two variables and thus suggesting that controlling FPR will enable the effective retention of AKD. 2.3. Factors for Improving FPR of AKD. Table 4 shows the experimental layout of the random-sequence seven-run fractional factorial design used to explore the optimization of AKD retention with different additives. 11229

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Table 4. Experimental Layout of Seven-Run Fractional Factorial Designs and AKD Retention no.

BCTMP (%)

1 2 3 4 5 6 7 8

20 20 20 20 40 40 40 40

ﬁxing agent (%/pulp) PAM PAM PAE PAE PAM PAM PAE PAE

0.025 0.050 0.050 0.025 0.050 0.025 0.025 0.050

AKD AKD-I AKD-II AKD-I AKD-II AKD-I AKD-II AKD-I AKD-II

ﬁller (%/pulp) GCC GCC PCC PCC PCC PCC GCC GCC

PAM/bentonite (%/pulp)

AKD retention (%)

0.025/0.125 0.050/0.250 0.050/0.250 0.025/0.125 0.025/0.125 0.050/0.250 0.050/0.250 0.025/0.125

88.6 95.3 95.0 93.0 91.3 94.3 94.0 93.0

15 30 15 30 30 15 30 15

in mill trials, i.e., PAE resin and highly branched cationic PAM (HB-CPAM). PAE resin has been widely used as a fixing agent, and it often increases AKD retention.31,32 Thus, a mill trial was carried out on a paper machine that produced wood-free paper with a basis weight of 80 g/m2. The stock was prepared with 15% softwood BKP, 65% hardwood BKP, and 20% BCTMP, with GCC and PCC used as fillers. The proportions of PCC and GCC were 70 and 30%, respectively, and the total ash content in the paper was approximately 26%. In the first trial, 0.05% PAE increased the ζ-potential of the machine chest and headbox stocks, which resulted in a 3−4% total retention improvement compared to the control run. This increased retention also increased the sizing degree, did not negatively affect paper formation, and decreased the number of waxy spots per spool by 0.9 spots per reel, which was measured using a web imaging system (ULMA, ABB Ltd., Louth, Ireland) installed at the end of the paper machine. Nevertheless, we required a greater reduction in the number of waxy spots per spool to produce a better-quality paper. To achieve this, in the second trial, we increased the PAE resin dosage to 0.1−0.2% and decreased the addition of sizing agent from 0.48 to 0.35% (Table 5). Despite this decreased addition

Figure 6 shows a Pareto chart summarizing the effect of different variables on AKD retention. Briefly, a Pareto chart is

Figure 6. Pareto chart of eﬀects for AKD retention, based on pooled data.

invaluable for determining the factors that need the most attention to improve a process. A bar graph with values plotted in decreasing order of the effect on a given system is the usual way to present the data on a Pareto chart.29 Thus, a Pareto chart is a basic tool of quality control, in which independent variables (in this case, retention aid dosage, AKD type, fixing agent type and dosage, etc.) are shown on the axis and dependent variables (in this case, AKD retention) are represented in bars of different lengths. The Pareto analysis showed that retention aid dosage, AKD type, and fixing agent type and dosage were the four main factors affecting AKD retention greater than a threshold (standardized) value. AKD retention increased in proportion to the retention aid dosage, which showed the importance of FPR for AKD sizing. The main effect plot (not shown) for AKD retention from the fractional factorial experiment data showed that AKD-II performed better than AKD-I when various stock components such as cationic starch and fixing agents were used before AKD addition. The use of fixing agent was found to be an important factor affecting the AKD retention. For example, the addition of polyamidoamine-epichlorohydrine (PAE) resin led to better AKD retention than the addition of a PAM-type fixing agent. The strong cationic charge density of the PAE resin made it effective as a fixing agent for AKD.30 2.4. Short-Term Mill Trials with PAE Fixing Agent. Among the seven factors tested, a 0.025% increase in the retention aid dosage was found to be the most effective way to increase AKD retention. This approach, however, deleteriously affected the formation and other properties of paper. As a second option, we compared the efficacies of two fixing agents

Table 5. Results of the First Mill Trial Using PAE Resin trial item PAE dosage AKD dosage OBA dosage retention

total ash dryer steam pressure (#3) formation index Stöckigt sizing degree defective waxy spots

unit

control

after 4 h

after 8 h

%/pulp %/pulp %/starch % kgf/cm2

0 0.48 1.60 75.5 31.3 1.18

0.1 0.40 1.73 81.4 39.5 1.08

0.2 0.35 1.90 84.6 44.1 1.08

% s EA/spool

49.6 11 19

51.0 13 14

49.6 15 15

of sizing agent, the Stöckigt sizing degree increased from 11 to 15 s. In addition, the FPR increased from 75.5 to 84.6%, and the FPR of ash increased substantially, from 31.3 to 44.1%. We also observed a concomitant improvement in the wire drainage and decreased steam consumption for drying, and the number of defective waxy spots per spool decreased from 19 to 14−15. However, 0.1% or more PAE also led to quenching of the fluorescent whitening agent, which necessitated an increase of the optical brightening agent (OBA) dosage from 1.60 to 1.90%. To solve this UV quenching effect by PAE, other fixing agents were explored. 2.5. Long-Term Mill Trial Using Highly Branched CPAM and Anionic AKD. Highly branched cationic PAM 11230

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(HB-CPAM) was selected as a new ﬁxing agent because of its high charge density and adsorption properties. A preliminary short-term trial was conducted to investigate this agent’s performance, which revealed that HB-CPAM was quite eﬀective in improving retention, wire drainage, sizing, drying energy reduction, and number of waxy spots. We thus conducted a long-term trial, the results of which are shown in Table 6, which indicates that HB-CPAM leads to FPR and

products. Thus, we switched to using only one type of AKD and HB-PAM fixing agent. As can be seen in Figure 7, these changes prevented any surge of spots and led to a substantial decrease in the total number of spots. These results indicated that the use of a new fixing agent and a single AKD application were efficacious in reducing the formation of waxy spots in low-grammage products and allowed cleaner operation of the papermaking process.

Table 6. Results of Long-Term Trial Using HB-CPAM in Production of 75 g/m2 Copy Paper

3. CONCLUSIONS A UV/vis spectrometry-based method for the analysis of AKD retention was developed, validated, and applied to investigate the role of several important factors on AKD retention. The effects of extraction time, DMAP/AKD ratio, and reaction time were investigated for the quantitative analysis of AKD using UV/vis spectrometry. The AKD retention was determined by extracting the AKD using chloroform and then treating it with DMAP, followed by a UV/vis analysis at 450 nm. The results showed that an extraction time of 60 min, a DMAP/AKD ratio of 120, and a reaction time of 90 min gave consistent and accurate measurements of AKD content in white water and paper stock. This method was used to investigate the effect of stock components on the quantitative measurement of AKD. A strong correlation between AKD retention and total FPR was found with the R2 value of 0.762. This indicated the importance of retention control to AKD sizing. To find effective ways of improving AKD retention, the effects of seven variablesretention aid dosage, fixing agent dosage, AKD type, fixing agent type, filler types, filler dosage, and pulp typeon AKD retention were tested. Retention aid dosage was found to be the most important, followed by AKD type, fixing agent type, and dosage, and thus the effects of different values of these four variables were examined in both laboratory and mill trials. The results showed that different retention aid dosages negatively affected paper formation, which made this approach impractical. However, a judicious selection of fixing agent and AKD type improved the AKD retention, drainage performance, and sizing efficiency without deleterious effects on paper formation and OBA quenching. Moreover, these optimal conditions led to substantial decreases in the number of waxy spots without any periodic surges in spot number over a long-term period of production.

HB-CPAM dosage AKD dosage OBA dosage retention total ash wire couch roll vacuum dryer steam pressure (#3) formation index Cobb sizing degree Stöckigt HST defective waxy spots

unit

control

trial

%/pulp %/pulp %/starch %

0 0.15 3.3 69.1 38.1 73 2.07 62.4 21 27 462 12.6

0.02 0.12 3.0 79.9 55.1 71 2.02 63.0 23 26 403 8.0

kPa kgf/cm2 % g/m2 s s EA/spool

ash retention increases of 10.8 and 17.0%, respectively. An increase in the sizing degree indicates that AKD retention also improves, and long-term defective spot numbers decrease substantially from 12.6 to 8.0 spots/reel. AKD sizing agents are stabilized emulsions that are usually made from cationic starch or charged polymeric stabilizers. However, cationic or anionic synthetic polyelectrolytes also have been used for AKD stabilization. To examine the eﬀect of AKD type on the defective waxy spot count, we carried out two trials using two AKDs. Alternating the use of AKD-I and AKDII has been a usual practice in the mill. However, laboratory experiments showed that single application of an anionic AKD was better in many respects. For instance, using anionic AKD only improved the Stöckigt sizing degree from 22.6 to 20.8 g/ m2. Thus, we decided to stop the alternating application of AKDs and switched to single use of anionic AKD-II. It can be seen in Figure 7 that the number of spots sporadically surged, sometimes to >100 per spool. These surges of spots occurred primarily when low-grammage products were made, because this necessitated the use of 1.5 times more AKD to keep the sizing level for the low-grammage

4. EXPERIMENTAL SECTION 4.1. Materials. Cationic and anionic AKD emulsions, denoted AKD-I (Taekwang Chemicals, Eumseong, Korea) and Table 7. Properties of Anionic and Cationic AKDs items

AKD-I

AKD-II

solids content (%) viscosity (cPs) average particle size (μm) ζ-potential (mV) stabilizer surfactant

19.9 6.6 0.41 +9.8 starch polymer

19.6 7.2 0.39 −11.9 starch sodium lignin sulfonate

AKD-II (Laton Korea, Gongju, Korea), respectively (Table 7), were used in both laboratory experiments and mill trials. The particle size and ζ-potential of AKD emulsions were determined using a Malvern Mastersizer (Malvern Instruments Ltd, Almelo, the Netherlands) and an electrophoretic light scattering spectrophotometer (ELS Z-1000, Otsuka Elec-

Figure 7. Number of spots observed over 3 years in 60 g/m2 woodfree papers. 11231

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Table 8. Operation Conditions of DDA Vacuum Drainage

Article

drainage

ﬁnish

−1

+30

start time (s) furnish stirring rate (rpm)

−90 pulp 400

−70 +AKD 400

−50 +ﬁller 400

−31 +PAM 800

−11 +bentonite 400

Vacuum pressure, 250 mbar; delay time, 1 s; forming time, 30 s.

to give a total weight of 50 g, and the resulting mixture was stirred. An aliquot of this mixture was analyzed using a UV/vis spectrophotometer (Varian, Mulgrave Victoria, Australia) at wavelengths of 450 and 338 nm, using chloroform as a reference. To explore the effect of the DMAP/AKD ratio on the reaction, the amount of DMAP added to the 0.1% AKD solution of chloroform was changed from 30 to 180 times of the AKD weight, the mixture was diluted further with chloroform, as before, and the resulting mixture was stirred for 2 h. Next, samples of the mixture were analyzed by UV/vis spectrometry. A calibration line was determined for the quantitative analysis of AKD by UV/vis spectrometry. Thus, 100 g of AKD emulsion at a concentration of 40−160 mg/L and 100 g of chloroform were placed in a separation funnel, and the funnel was then vigorously shaken to extract AKD. Next, DMAP was added in a weight ratio of 120:1 of AKD weight, and the resulting mixture was reacted for 2 h. After this, an aliquot of the mixture was analyzed by UV/vis spectrometry, as before. AKD calibration lines were determined for AKD-I and AKD-II emulsions. To evaluate AKD retention, an extraction method using chloroform as a solvent was used to determine the amount of AKD in white water. To determine the extraction time required for the complete extraction of AKD, 500 g of AKD emulsion at a concentration of 50 ppm was placed in a separation funnel and 500 g of chloroform was added. After shaking the funnel for 5−180 min, the UV/vis absorption of an aliquot was observed. The ratio of DMAP/AKD was fixed at 120:1 to ensure the complete reaction of AKD, and the mixture was allowed to react for 2 h. To investigate the effect of pulp fiber and fillers on AKD extraction, slurries of hardwood BKP, BCTMP, GCC, and PCC at 0.1% consistency were prepared. Next, 10 wt % AKD (with respect to the dry weight of the pulp or filler) was added to each slurry, and each of the resulting mixtures was subject to an extraction and quantification procedure, as above. 4.2.2. Effects of Pulp and Filler Types on AKD Retention. To investigate the effects of pulp type, hardwood BKP, BCTMP, and a 50/50 mixture of these two pulps were used. Thus, 500 mL of a prepared stock of one of the above pulps at 0.5% consistency was placed in a dynamic drainage analyzer (DDA; AB Akribi Kemikonsulter, Sundsvall, Sweden) and

Table 9. Seven Factors Examined for Their Eﬀect on AKD Retention no.

variable

1 2 3 4 5 6 7

pulp type fixing agent type fixing agent dosage AKD type filler type filler dosage PAM/bentonite dosage

type of variable BCTMP 20% PAM 0.025% AKD-I GCC 15% 0.025/0.125%

BCTMP 40% PAE 0.050% AKD-II PCC 30% 0.050/0.250%

tronics, Hirakata, Japan), respectively. The two AKDs were very similar in most properties except the ζ-potential: AKD-I was positively charged, while AKD-II was negatively charged. Eucalyptus hardwood bleached kraft pulp (BKP; CMPC Celulosa, Brazil) and bleached chemithermomechanical pulp (BCTMP; Temcell, Tembec Inc., Québec, Canada) were used for papermaking. Hardwood BKP was beaten in a Valley beater to 450 ± 10 mL Canadian standard freeness (CSF) and diluted to a consistency 0.5%. Aspen BCTMP was simply disintegrated and diluted to 0.5%. Chloroform (Sigma-Aldrich) was used for AKD extraction, and 4-dimethyl aminopyridine (DMAP; Sigma-Aldrich) was used as a reactant for the UV/vis spectrometric analysis of AKD.24 Ground calcium carbonate (GCC; Omya Korea, Jeongseon, Korea) and on-site precipitated calcium carbonate (PCC; Omya Korea, Ulsan) with average particle sizes of 1.1 and 2.4 μm, respectively, were used as fillers. Cationic starch (Samyang Genex, Incheon, Korea) with a 0.06 degree of substitution was used as an internal additive. Two retention systems were used: one consisted of cationic poly(acrylamide) (PAM; Percol63) and bentonite (Hydrocol OTK; Ciba Specialty Chemicals Korea, Seoul, Korea), which is often referred to as a Hydrocol retention system,33,34 and the other consisted of poly aluminum chloride (PAC), anionic PAM, and anionic micropolymer, denoted a PerForm system (PerForm SP; Solenis Korea, Kimcheon, Korea). 4.2. Methods. 4.2.1. Quantitative Analysis and Retention Measurement of AKD. First, we identified the required reaction time for AKD and DMAP. In a round-bottom flask, 4.8 g of DMAP was added to 4 g of a 0.1% AKD solution of chloroform. This mixture was diluted further with chloroform

Figure 8. Flow diagram of the gap-former paper machine used for examining the eﬀect of certain variables and showing the points of introduction of additives. Fixing, ﬁxing agent; A-PAM, anionic poly(acrylamide); MP, micropolymer.. 11232

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stirred at 400 rpm for 20 s. After this time, 0.5% w/w AKD (based on the dry weight of pulp) was added to the stock, and the resulting mixture was stirred for 40 s and then drained. The DDA vacuum level of the dynamic drainage analyzer was adjusted to 250 mbar, and the first-pass retention value was determined from the solids content and turbidity of the drained white water. To determine the AKD retention, a 100 g sample of white water was mixed with 100 g of chloroform in a separation funnel and vigorously shaken for 1 h to extract AKD. Next, a 50 g aliquot of this chloroform solution was taken and treated with DMAP whose weight is equal to the weight of 120 times of AKD, and an aliquot of the resulting mixture was analyzed by UV/vis spectrometry. The effect of filler types and retention systems on AKD retention were evaluated using the same method used to examine the effect of pulp type. AKD and filler were added after 20 and 40 s of stirring, respectively, and the resulting mixture was drained 20 s after the addition of filler. When the retention aid was used, the addition points and stirring speed shown in Table 8 were used in the experiment. They were chosen to simulate the conditions of the papermaking process. 4.2.3. Influence of Additives on AKD Retention and Mill Trials. To investigate the effect of papermaking raw materials or additives on AKD retention, a fractional factorial experiment design was used. Each of the seven factors shown in Table 9 was examined at two levels to assess the effect of these factors on AKD retention in a laboratory setting, and the resulting data were statistically analyzed. Next, mill trials were performed to examine the effect of the two most important variables, as determined by the above laboratory experiment, on AKD retention. These trials were performed on a gap-former paper machine producing printing and writing grades papers at a machine speed of 1200 m/min. The points at which the additives were introduced are depicted in Figure 8.

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Article

REFERENCES

(1) Downey, W. F. Higher Alkyl Ketene Dimer Emulsion. U.S. Patent US2,627,4771949. (2) Davis, J. W.; Robertson, W. H.; Weisgerber, G. A new sizing agent for paper - alkylketene dimers. Tappi J. 1956, 39, 21−23. (3) Nahm, S. H. Direct evidence for covalent bonding between ketene dimer sizing agents and cellulose. J. Wood Chem. Technol. 1986, 6, 89−112. (4) Roberts, J. C.; Garner, D. N. The mechanism of alkylketene dimer sizing of paper. Part 1. Tappi J. 1985, 68, 118−121. (5) Lindström, T.; O’Brian, H. On the mechanism of sizing with alkylketene dimers. Nord. Pulp Pap. Res. J. 1986, 1, 34−42. (6) Lindström, T.; Söderberg, G. On the mechanism of sizing with alkylketene dimers. Nord. Pulp Pap. Res. J. 1986, 1, 26−33. (7) Lindström, T.; Söderberg, G. On the mechanism of sizing with alkylketene dimers. Nord. Pulp Pap. Res. J. 1986, 1, 31−38. (8) Marton, J. Practical aspects of alkaline sizing - on kinetics of alkyl ketene dimer reactions: hydrolysis of alkyl ketene dimer. Tappi J. 1990, 73, 139−143. (9) Oh, W. D.; Shin, D. S. Effects of hydrolysis product of AKD, extractives of pulp and additions of calcium carbonate filler on the kinetic coefficient of friction of paper surface. J. Korea Tappi 1994, 26, 7−14. (10) Novak, R. W.; Rende, D. S. Size reversion in alkaline papermaking. Tappi J. 1993, 76, 117−120. (11) Colasurdo, A. R. The interactions of alkylketene dimer with other wet-end additives. Tappi J. 1992, 75, 143−149. (12) Ö dberg, L.; Lindström, T.; Liedberg, B.; Gustavsson, J. Evidence for β-ketoester formation during the sizing of paper with alkyl ketene dimers. Tappi J. 1987, 70, 135−139. (13) Lee, H. L.; Luner, P. Effect of relative humidity and unreacted AKD on AKD sizing. Nord. Pulp Pap. Res. J. 2005, 20, 227−231. (14) Goldstein, S. D. Key alkaline wet- and dry-end conversion program decisions: an overview. Tappi J. 1992, 75, 85−92. (15) Petander, L.; Ahlskog, T.; Juppo, A. J. Strategies to reduce AKD deposits on paper machines. Paperi ja puu 1998, 80, 100−103. (16) Dart, P. J.; McCalley, D. V. Determination of alkylketene dimer sizing agent products in paper by capillary gas chromatography. Analyst 1990, 115, 13−16. (17) Yano, T.; Ohtoni, H.; Tsuge, S. Determination of neutral sizing agent in paper by pyrolysis-gas chromatography. Analyst 1992, 17, 849−852. (18) Asakura, K.; Iwamoto, M.; Isogai, A. The effects of AKD oligomers present in AKD wax on dispersion stability and paper sizing performance. Nord. Pulp Pap. Res. J. 2006, 21, 245−252. (19) Zule, J.; Dolenc, J. Determination of AKD sizing agents in papermaking systems by gas chromatography. Acta Chim. Slov. 2003, 50, 115−122. (20) Lindström, T.; Söderberg, G. On the mechanism of sizing with alkylketene dimers. Nord. Pulp Pap. Res. J. 1986, 1, 39−45. (21) Martorana, E.; Fisher, S.; Kleemann, S. Quantitative analysis of synthetic sizing agents (ASA/AKD) using NIR spectroscopy. Nord. Pulp Pap. Res. J. 2009, 24, 335−341. (22) Seo, W.-S.; Cho, N. S.; Ohga, S. Possibility of hydrogen bonding between AKD and cellulose molecules during AKD sizing. J. Fac. Agric., Kyushu Univ. 2008, 53, 405−410. (23) Jaycock, M. J.; Roberts, J. C. A new procedure for the analysis of alkylketene dimers in paper. Paper Technol. 1994, 35, 38−42. (24) Min, C. K.; Shin, D. S. A quantitative analysis method for studying AKD hydrolysis. J. Korea Tappi 1998, 30, 29−37. (25) Hubbe, M. A.; Gill, R. A. Fillers for papermaking: A review of their properties and usage practices, and their mechanistic role. BioResources 2016, 11, 2886−2963. (26) Hubbe, M. A., In Filler Particle Shape vs. Paper Properties - A Review, TAPPI Spring Technical Conference Proceedings, Paper 7-3, 2004; pp 1−10. (27) Patton, P. A. In On the Mechanism of AKD Sizing and Size Reversion, TAPPI Spring Technical Conference Proceedings; TAPPI Press: Atlanta, 1991; pp 415−424.

AUTHOR INFORMATION

Corresponding Author

Hak Lae Lee − Department of Forest Sciences, College of Agriculture & Life Sciences, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, South Korea; State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, People’s Republic of China; Phone: +82 2 880 4786; Email: lhakl@snu.ac.kr

Authors

Kyong Ho Lee − Hankuk Paper Manufacturing Co. Ltd., Ulsan 45010, South Korea Hye Jung Youn − Department of Forest Sciences, College of Agriculture & Life Sciences, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, South Korea; State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, People’s Republic of China; orcid.org/0000-0002-25030471 Complete contact information is available at: https://pubs.acs.org/10.1021/acsomega.0c01374 Notes

The authors declare no competing ﬁnancial interest. 11233

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(28) Voutilainen, P. In Competitive Adsorption of Alkyl Ketene Dimer on Pulp Fibers and CaCO3 Fillers, International Paper Coating Chemistry Symposium Notes; CPPA: Canada, 1996. (29) Ryan, T. P. Statistical Methods for Quality Improvement, 3rd ed.; Wiley: Hoboken, NJ, US, 2011. (30) Isogai, A. Effect of cationic polymer addition on retention of alkyl ketene dimer. J. Pulp Pap. Sci. 1997, 23, 276−281. (31) Isogai, A. Factors Inﬂuencing on Retention of Alkylketene Dimer. In The Fundamental of Papermaking Materials, Baker, C. F., Ed.; Pira International: UK, 1997; Vol. 2, pp 1047−1069. (32) Moyers, B. M. Diagnostic sizing loss problem solving in alkaline systems. Tappi J. 1992, 75, 111−115. (33) Ham, C.-H.; Lee, H.-L. Performance of cationic guar gums in closed papermaking systems. J. Korea Tappi 2008, 40, 1−8. (34) Lee, J.-Y.; Youn, H.-J.; Lee, H.-L. Evaluation of stock flocculation phenomena based on turbidity measurement. J. Korea Tappi 2008, 40, 10−15.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

A comparative study of morphological characteristics of mediumǦdensity fibreboard dust by sieve and image analyses Tao Ding (1), Jiafeng Zhao (1), Nanfeng Zhu (1) and Chengming Wang (2). Sanding dust is the main source of dust emission during the manufacturing process of medium-density fibreboard (MDF), and particle size and shape characteristics are the fundamental properties influencing its environmental influence and handling behaviours. However, there are few deep and comprehensive researches on the morphology of MDF sanding dust. In this study, the morphological characteristics of MDF sanding dust were explored by sieve and image analyses. It was found that more than 95% of MDF sanding dust was inhalable particles smaller than 100 μm, which poses a considerable potential risk to human health and safety, especially with the presence of other chemical constituents. The particle size span of MDF dust was relatively wide though the particle surface texture was quite uniform. The particle geometric proportion represented by aspect ratio decreased markedly with the reduction of particle size. The larger particles presented typical anisotropic structure, while the smaller ones showed homogeneous appearance, indicating quite complex handling behaviours. In addition, image analysis was found to provide a better insight into the morphological characteristics of MDF sanding dust compared to sieve analysis, and could be a promising dust morphology evaluation technology. Contact information: 1: Nanjing Forestry University, 159 Longpan Rd., Nanjing 210037, China; 2: Holtrop & Jansma BV Qingdao Office, No.1 Shangma Section of Aodong Road, Qingdao 266114, China. Ding et al. J Wood Sci (2020) 66:55 https://doi.org/10.1186/s10086-020-01896-x This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

Page 1 of 10

Article 6 – Wood Panel

(2020) 66:55 Ding et al. J Wood Sci https://doi.org/10.1186/s10086-020-01896-x

Journal of Wood Science

Open Access

ORIGINAL ARTICLE

A comparative study of morphological characteristics of medium-density fiberboard dust by sieve and image analyses Tao Ding1, Jiafeng Zhao1, Nanfeng Zhu1*

and Chengming Wang2

Abstract Sanding dust is the main source of dust emission during the manufacturing process of medium-density fiberboard (MDF), and particle size and shape characteristics are the fundamental properties influencing its environmental influence and handling behaviors. However, there are few deep and comprehensive researches on the morphology of MDF sanding dust. In this study, the morphological characteristics of MDF sanding dust were explored by sieve and image analyses. It was found that more than 95% of MDF sanding dust was inhalable particles smaller than 100 μm, which poses a considerable potential risk to human health and safety, especially with the presence of other chemical constituents. The particle size span of MDF dust was relatively wide though the particle surface texture was quite uniform. The particle geometric proportion represented by aspect ratio decreased markedly with the reduction of particle size. The larger particles presented typical anisotropic structure, while the smaller ones showed homogeneous appearance, indicating quite complex handling behaviors. In addition, image analysis was found to provide a better insight into the morphological characteristics of MDF sanding dust compared to sieve analysis, and could be a promising dust morphology evaluation technology. Keywords: Medium-density fiberboard, Sanding dust, Particle size, Particle shape, Sieve analysis, Image analysis

Introduction Medium-density fiberboard (MDF) is a wood-based panel product made primarily from wood fibers, which are bonded together by synthetic resins under heat and pressure. MDF is a prominent nonstructural composite widely used in furniture and cabinet industries. In 2017, the world’s fiberboard output surpassed 118 million m3, and China alone contributed about 60 million m3 [1]. Panel sanding is a critical operation in the finishing stage of MDF manufacturing because it determines both the thickness and surface quality of the product. Large amounts of dust are generated in MDF sanding process, and the dust load could be as high as 53.67 kg/m3 [2], which means 50t sanding dust may have to be handled every day in a typical modern MDF mill with an annual *Correspondence: znanf@njfu.edu.cn 1 Nanjing Forestry University, 159 Longpan Rd., Nanjing 210037, China Full list of author information is available at the end of the article

output of 300 thousand m3. Although dust collecting and conveying systems have been equipped in most MDF mills, the system failures or safety accidents still occur occasionally. The handling of sanding dust affects penal grade, environmental quality and workplace safety of MDF manufacturing. If sanding dust had not been smoothly sucked into suction hoods, sand belts would be clogged, which would in turn deteriorate sanding quality and become the main reason for the failure of sand belts [3]. The MDF particles leaked into the air are responsible for respiratory diseases among continuously exposed workers. Wood dust is classified as carcinogenic to humans [4], and MDF dust is more hazardous as MDF is usually impregnated with urea–formaldehyde (UF) resin. The chemical composition makes it a source of formaldehyde exposure [5]. MDF dust was reported to cause more nasal symptoms among workers than solid wood dust [6]. Sanding dust particles are regarded as the finest dust in

© The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Ding et al. J Wood Sci

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the wood processing industry [7], and are more likely to penetrate into human respiratory system. The amount of respirable dust generated during the sanding of MDF is more than other wood working processes, including solid wood sanding [8, 9]. The fineness of MDF dust also increases both the feasibility and violence of dust explosion [10, 11]. Proper handling of MDF sanding dust requires a full understanding of its properties. Morphological characteristics including particle size distribution (PSD) and shape distribution are the fundamental factors influencing dust handling behaviors such as flowability, bulk density and compressibility, etc. [12–14]. Large particles with spherical shape generally have good flowability, which deteriorates with decreased particle size as the inter-particle cohesive force increases [15]. For irregularly shaped particles, the relative motion becomes difficult due to the presence of more contacting points between them. If elongated and hook-shaped particles are involved, it will be more complicated because they tend to form bridges by particle interlocking [16]. Limited studies have been performed on size and shape characteristics of MDF sanding dust. Mazumder suggested that a significant portion of MDF sanding dust was respirable particles with aerodynamic diameters smaller than 10 μm, and that the particles were of irregular shapes with sharp edges [5]. Chung et al. investigated the MDF sanding dust emitted from handheld sander and found the portion of respirable dust was less than 10%, but a portion as high as 30% was also cited in his paper [9]. Očkajová et al. studied the size distribution of MDF sanding dust by sieve analysis and found that 96.16% of the sample particles were smaller than 100 μm, and that the most common particles were in the range between 32 and 63 μm [17]. No quantitative study on shape distribution of MDF sanding dust has been found by the authors of this paper. In this study, morphological characteristics of MDF sanding dust were investigated by sieve analysis (SA) and image analyses (IA). SA has been widely used to determine the PSD of bio-based particles. Its popularity derives from low cost, simple procedure, straightforward results and the similarity to the particle separating practice in wood-based panel industry. SA is a standard method to determine the PSD of some bio-based particles [18–20], and has been applied in many scientific studies [21–23]. But in recent years, questions arose on the competency of SA for bio-based particles. The size that SA measures is the second smallest dimension, i.e., the width of a particle [21, 24]. For spherical particles, the PSD obtained by SA is quite reasonable. But most wood dust generated from mechanical processes is irregularly shaped due to

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the anisotropic structure of wood. In this case, SA alone can barely present the morphological characteristics of wood dust. Besides, it is hard for the elongated or fibrous wood particles to fall through the sieves. The sieving efficiency, the percentage of the particles that can properly fall through the sieves according to their width, was reported around 70% [21]. In some studies, IA was suggested as an alternative method or a combination of SA and IA was applied to get a more comprehensive understanding of particle morphology [24, 25]. Once considered time consuming, IA systems are now capable of handling a large quantity of particles and presenting the statistical results instantaneously. The major advantage of IA is that, besides size distribution, it can give quantitative particle shape distribution. In this study, 2 IA technologies, i.e., scanning electron microscopy (SEM) and flatbed scanning image analysis, were applied. The former was used as a qualitative description method and the latter provided quantitative analysis. The results were compared with those of the SA to evaluate the robustness of the technologies.

Experimental Materials

MDF sanding dust was taken from a MDF mill in Jiangsu Province, China. The main panel constituents were hybrid poplar (Populus sp.) ﬁbers and UF resin. The panel sanding line was composed of 3 wide belt sanding machines. Five types of sanding belts were mounted and the grit sizes were P36, P80, P120, P150 and P180 from the entry to the outlet of the sanding line. MDF panels were fed at a speed of 55 m/min and sanded at a speed of 1460 rpm. The dust emitted during the sanding process was collected by a dust collecting system and stored in a silo where the dust was sampled for the experiments. The moisture content of the sample dust was 6.5%. Sieve analysis (SA)

In the sieve analysis, 85 g sample particles were sieved by a sieve shaker (A3, Fritsch GmbH, Idar-Oberstein, Germany) for 10 min with 3 mm amplitude. The sieve stack was composed of 5 sieves, and their mesh sizes were 1000, 500, 250, 100 and 40 μm from the top to the bottom, respectively. Wood dust retained on each sieve and the collecting pan was then weighted for size distribution by an electronic balance (BS2202S, Sartorius AG, Goettingen, Germany). The analysis was performed twice and the average values were considered the results. Scanning electron microscopy (SEM)

The particles used for SEM analysis were taken from subsamples left on each sieve and the collecting pan. They were dried to the oven dry state, and then coated with

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gold using a sputter coater (JFC 1600, JEOL Ltd, Tokyo, Japan) and placed in a SEM (JSM 7600F, JEOL Ltd, Tokyo, Japan) for photographing.

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a particle projection area and provides the information of particle surface structure. The aspect ratio (AR) of the dust particle was calculated by Eq. 1:

Flatbed scanning image analysis

Din

convex hull

For the flatbed scanning, 20 mg sample particles were dispersed by a vacuum dispersion device (VDD270, Occhio s.a., Angleur, Belgium) where they were placed on a plastic membrane covering the top of a cylindrical chamber as the air inside was pumped out. Once the vacuum level in the chamber was low enough to destroy the plastic membrane, the particles fell into the chamber and gently settled on the glass plate of the image analyzer (500 Nano, Occhio s.a., Angleur, Belgium) for image analysis. The images of the scanned samples were instantaneously analyzed by the built-in software CallistoEXPERT for calculating particle size and shape distribution. The number-weighted statistical results were converted to the mass-weighted ones by assuming that all particles have identical flatness ratios. The inner diameter (Din), i.e., the biggest circle inscribed into the projection area of a particle (Fig. 1) was chosen as the representative size parameter because it showed a good correlation with sieving diameter [26]. It has been suggested that one or two key shape factors can well describe the shape characteristics of a certain kind of particle [27]. Since the basic constituent of MDF is wood fiber, the length-to-width ratio was chosen as a macro-shape descriptor to describe particle geometric proportion. Particle solidity was chosen as a mesoshape descriptor, which reflects the overall concavity of

Fig. 1 Inner diameter, convex hull, length and width of a particle projection

AR = 1 −

W , L

(1)

where W is the width of the smallest box that contains the projection of a particle with the principal directions the same as the projection of the particle, and L is the length of the box (Fig. 1). Solidity was calculated by Eq. 2:

S , SA

(2)

where S is the projection area of the particle, and SA is the area of the convex hull bounding the projection (Fig. 1). The relative extent of size or shape distribution was evaluated by relative span (RS):

RS =

P90 − P10 , P50

(3)

where P90, P50 and P10 are the 90th, 50th and 10th percentiles of the size and shape distribution, respectively.

Results and discussion Morphological characteristics determined by SA and SEM

The SA showed that the great majority (96%) of the MDF sanding dust particles was smaller than 100 μm (Fig. 2). They belong to inhalable particles tending to stay longer and travel wider in the air, which are unsuitable for the living and working environments [8, 28]. Notably, the particles smaller than 40 μm accounted for 79.6%, which are capable of penetrating into the upper respiratory tract and pose health risk to humans [5, 29]. The size characteristic distinguishes sanding dust from wood dust emitted during other machining processes, like sawing, planning and milling. There are orders of magnitude differences in size between them. The SA of pine sawdust by Chaloupkova et al. showed that only 11.93% of the particles were smaller than 630 μm [22]. A similar study on timber sawdust performed by Benthien et al. also indicated a 20% portion in the same range [25]. As mentioned above, smaller size means lower flowability due to the increase of cohesive force between particles. For food particles, the influence of cohesive force could still be significant when the particle size was up to 200 μm [15, 30]. The size distribution of MDF sanding dust clearly indicates an even lower flowability. Particles retained on each sieve were observed by SEM. Fibrous particles were found in the sample retained on the 40-μm mesh-size sieve (Fig. 3a). Most of them were

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Fig. 2 Mass-weighted size distribution of MDF sanding dust determined by sieve analysis (histogram: diﬀerential size distribution, line: cumulative size distribution)

Fig. 3 SEM images of MDF sanding dust. a Dust retained on the 40-μm sieve, b dust passing through the 40-μm sieve

around 1 mm in length and 10 μm to 20 μm in width, similar to the size of typical hardwood fibers [31]. No fibrous particle existed in the sample falling down the 40-μm sieve though some elongated particles were found (Fig. 3b). These particles, and those with even shorter lengths, were irregularly shaped fiber fragments

generated by transwall failure of the fibers under the sanding forces, which were hard to be classified into a certain shape category. However, there also existed some particles with relatively regular shape, like crystal or brick shape as shown in Fig. 4. They were remarkably different from wood particles in shape and surface texture. This

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Fig. 4 Non-wood components in MDF sanding dust sample. a Crystal-shaped particle; b brick-shaped particle

indicated the presence of components other than wood in the MDF sanding dust, which should be derived from chemical components in the MDF panel like UF resin or the combination of wood ﬁbers and chemical additives. In small quantities as they presented, the physiochemical properties of MDF sanding dust could be signiﬁcantly changed to cause environmental impacts. For example, the burning and pyrolysis of UF-containing wood wastes can release environmentally harmful gases, which results in a restriction of their energy utilization [32]. Morphological characteristics determined by flatbed scanning image analysis

The IA provided much detailed statistical results on particle morphology. According to Table 1, the median size (50th percentile value) of MDF sanding dust was 12.90 μm, and the mean value was a little bit higher (17.28 μm), which might be due to the existence of relatively large particles with the size up to 192.70 μm. The RS of particle size was 2.20, which is wider than some other bio-based particles [33], indicating the heterogeneity of MDF sanding dust size. Sub-micrometer particles as small as 0.66 μm were also detected, showing the presence of ultraﬁne particles in MDF sanding dust. Similarly, particles smaller than 0.1 μm was detected when sanding MDF panels with

P240 sandpaper according to Welling et al. [7]. In general, sub-micrometer is the domain of fumes and smokes, and mechanical processing of solid materials seldom produces particles less than 1 μm, which might be attributed to the volatile compounds in the MDF resin [7]. It can therefore be suggested that the existence of the resin in MDF not only influences the physiochemical properties of MDF sanding dust, but also extends the lowest limit of particle size. The PSD obtained by IA also showed the dominance of inhalable particles in MDF sanding dust with 99.6% of the sample particles smaller than 100 μm (Fig. 5). What’s more, of all the particles, around one-third was smaller than 10 μm and termed PM10, which can penetrate into the lower region of human respiratory tract. A small quantity (1.5%) with the size lower than 2.5 μm termed PM2.5 was also detected, which are fine inhalable particles to have the greatest health risks to humans [29]. The shape analysis showed that the MDF sanding dust samples had a pretty low aspect ratio as a whole, and the mean AR value was 0.32, almost the same as the median value of 0.31 (Table 1), which indicated that the width of at least 50% of the particles was comparable to the length. This coincided with the visual observation of SEM pictures (Fig. 3b). But elongated or fibrous particles also existed. Around 10% of the particles had length-to-width

Table 1 Size and shape distributions of MDF sanding dust determined by flatbed scanning image analysis

Din (μm)

Mean

Min

P10

P25

P50

P75

P90

P98

Max

17.28

0.66

3.08

4.83

7.93

12.90

20.47

33.15

59.41

192.70

2.20

0.32

0.00

0.06

0.14

0.22

0.31

0.42

0.53

0.63

0.86

1.26

Solidity

0.89

0.03

0.65

0.74

0.84

0.93

0.96

0.98

0.99

1.00

0.26

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Page 6 of 9

Fig. 5 Mass-weighted size distribution of MDF sanding dust determined by ﬂatbed scanning image analysis (histogram: diﬀerential size distribution, line: cumulative size distribution)

ratios bigger than 2, and the particles with AR as high as 0.86 existed, representing wood fibers observed in the SEM picture (Fig. 3a), which are likely to interlock with each other and form mechanical bridges in the handling processes. But given that they only accounted for less than 2% of the total in weight, interlocking should not be considered as the main mechanism influencing the handling behaviors of MDF sanding dust. The AR of MDF sanding dust showed different distribution characteristics in different size ranges. Larger particles presented a wider AR distribution. But for smaller particles, a much less AR variation was found (Fig. 6). The AR of particles less than 10 μm were concentrated in a range between 0.2 and 0.3, which meant the size reduction gradually reduces the shape variation of MDF sanding dust and made them more homogeneous. This seems to be a general trend for bio-based particles and has been repeatedly reported [23, 34, 35]. Figure 7 illustrates how particle shape varies with size reduction. The big particles shown in Fig. 7a are fragments of fiber bundles with various aspect ratios while the fine particle shown in Fig. 7b presents an appearance similar to a sphere. It can also be found that big particles inherit the anisotropic nature of wood. The length of the particles is parallel to the longitudinal direction of wood fibers, which makes the particle orientation an important factor influencing

Fig. 6 Shape distribution of MDF sanding dust and its correlation with particle size

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Page 7 of 9

Fig. 7 Shape comparison of big (a) and small (b) MDF sanding particles

Comparison between SA and IA

fibers. Some of sieve apertures were even clogged by the partially passed fibers in the vibration process, which was the main reason for the 2% mass loss in the SA experiments. That’s why fibers could still be found in the sample retained on the 40 μm sieve, but no single one was present in the sample passing through (Fig. 3). Besides shape characteristics, factors like the impact forces between the particles during sieve vibration and the cohesion of small particles all contribute to the retaining of particles on the sieves. Compared to SA, IA obviously provided a better insight into the morphological characteristics of MDF sanding dust by providing detailed information down to the submicrometer level. SA did not present enough information on the fine particles due to the limit of mesh size, which makes it more suitable for the analysis of coarse particles from sawing or milling processes. Particle irregularity, especially aspect ratio, was another factor limiting the application of SA for wood particles, which was the main contributor to the under-evaluation of fine particles smaller than 40 μm in the SA study.

Both SA and IA revealed that more than 95% of the MDF sanding dust particles was suspended particles, most of which were smaller than 40 μm and capable of entering in the human respiratory tract. However, difference existed between SA and IA in the mass percentage of those smaller than 40 μm. According to IA, more than 90% of the particles fell in this range while it was 79.6% in SA. Several factors contribute to the statistical difference between IA and SA. For the fibrous particles, it is possible to fall through millimeter-wide apertures after sufficient vibration. But the penetration of apertures as small as 40 μm wide can hardly be achieved as they are much smaller than the longitudinal dimension of the

Conclusions The morphology of MDF sanding dust was investigated by sieve analysis, scanning electron microscopy and ﬂatbed scanning image analysis. The great majority of the MDF sanding dust was found to be inhalable particles smaller than 100 μm. Moreover, other chemical components were found in the dust samples, which inﬂuences not only the size distribution, but also physiochemical properties of MDF sanding dust. The relative span of particle size was wide. Bigger particles showed a wider distribution of aspect ratio, while smaller ones exhibited homogeneous appearance. Only the surface texture was

its handling properties. On the contrary, when the particle size is similar to the fiber cell wall thickness, almost no anatomical characteristics of wood can be found, indicating a homogeneous handling behavior totally different from that of big particles. Contrary to AR, solidity analysis revealed a very narrow distribution with a RS value of only 0.26. The mean and 50th percentile solidity values were 0.89 and 0.93, respectively (Table 1). The high solidity means less concave positions on MDF sanding dust surfaces, which can thereby be characterized as flat or smooth surface. The AR and solidity values demonstrated that full breakage and surface erosion of wood fibers occurred during the sanding of the MDF panels. The wood fibers were subject to the interactions with the sanding belt grits, the panel surface and other particles, which broke the fibers and eroded small irregularities on particle surfaces, resulting in smaller, shorter and smoother particles discovered in this study.

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uniform and could be characterized as smooth surface. Taken together, MDF sanding dust might pose a considerable occupational health risk and imply quite complex handling behaviors as well. For the MDF industry, care should be taken when the sanding dust is handled. Frequent inspections are suggested to be made where the particles are easy to accumulate and filtering materials with higher efficiency are recommended to separate them from the air. The sieve analysis presented particle size distribution comparable to the image analysis, but it failed to provide detailed information on fine fractions of the sample. It is suggested to be applied for homogeneous or coarse particles ready to settle down in the air. The image analysis demonstrated itself a robust particle morphology analysis technology by offering detailed results of both size and shape distribution and their correlations. It deserves further exploration for the better application in the field of bio-particle analysis. Abbreviations MDF: Medium-density fiberboard; UF: Urea formaldehyde; PSD: Particle size distribution; SA: Sieve analysis; IA: Image analysis; SEM: Scanning electron microscopy; AR: Aspect ratio; RS: Relative span. Acknowledgements The authors acknowledge the help of the Advanced Analysis and Testing Center of Nanjing Forestry University and the China office of Occhio s.a. Authors’ contributions TD analyzed the experimental data and drafted the manuscript. JZ performed the experiments and prepared the figures. NZ is the project leader and responsible for the experimental design and manuscript review. CW collected the MDF sanding dust samples and contributed to the image analysis. All authors read and approved the final manuscript. Funding The work in this paper is financially supported by the National Key Research and Development Program of China (2016YFD0600703). Availability of data and materials Most data analyzed during this study are included in this published article. The supplementary information is available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Author details 1 Nanjing Forestry University, 159 Longpan Rd., Nanjing 210037, China. 2 Holtrop & Jansma BV Qingdao Office, No.1 Shangma Section of Aodong Road, Qingdao 266114, China.

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2. 3.

10.

11. 12.

13.

14.

15. 16. 17.

18.

19.

20.

21.

22.

Received: 13 March 2020 Accepted: 29 June 2020 23. 24.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Structural evaluation of chitosanǦ modified precipitated calcium carbonate composite fillers for papermaking applications Indrasena Ghosh (1), Chhaya Sharma (1), Rita Tandon (2). Industries from different business sectors are facing challenges against global competitions for the development of sustainable and renewable products in the twenty-first century. Likewise, constant effort from pulp and paper manufacturers in minimizing paper cost with better quality in the active field of filler modification technology is much appreciated. In the present study, chitosan has been explored as a surface modifier alternative to conventional starch for precipitated calcium carbonate (PCC) to design chitosan/PCC composite filler. Two different dissolution mediums, hydrochloric and acetic acid, for chitosan have been seen to affect PCC crystals. Commercial PCC comprises mostly aragonite polymorphs along with some calcite crystals as implied by FTIR, XRD and FE-SEM images. It is interesting to note that surface treatment of PCC with 4.5% chitosan can successfully induce crystal transformation of PCC from aragonite to calcite polymorphs. Further, the deposition of chitosan was estimated from TOC measurements and the presence of deposited amount was validated from TGA analysis. Moreover, the introduction of chitosan (dissolved in HCl) to PCC dispersion was found to raise the zeta potential from − 14.43 to − 11.3 mv. Finally, the tensile strength of handsheets increased by 8.2% with 20% enhancement in ash with chitosan/PCC composite filler compared to the unmodified PCC. Therefore, bio-based PCC composites which proved to be promising for the development of high ash paper without compromising essential properties may result in saving wood pulp and production cost. Thus, implementing such seafood waste as a value-added additive is beneficial both to the industries and the environment because of its biodegradability and eco-friendliness. Contact information: 1: Department of Paper Technology, IIT Roorkee, Saharanpur Campus, Saharanpur, Uttarpradesh 247001, India; 2: Central Pulp and Paper Research Institute, Saharanpur, Uttarpradesh 247001, India. SN Applied Sciences (2020) 2:1577 https://doi.org/10.1007/s42452-020-03313-w Material in this journal is free to access for the first two years and is well worth checking out: https://www.springer.com/journal/42452.

Page 1 of 15

Article 7 – PCC Fillers

Research Article

Structural evaluation of chitosan-modified precipitated calcium carbonate composite fillers for papermaking applications Indrasena Ghosh1 · Chhaya Sharma1 · Rita Tandon2 Received: 15 April 2020 / Accepted: 7 August 2020 / Published online: 28 August 2020 © Springer Nature Switzerland AG 2020

Abstract Industries from different business sectors are facing challenges against global competitions for the development of sustainable and renewable products in the twenty-first century. Likewise, constant effort from pulp and paper manufacturers in minimizing paper cost with better quality in the active field of filler modification technology is much appreciated. In the present study, chitosan has been explored as a surface modifier alternative to conventional starch for precipitated calcium carbonate (PCC) to design chitosan/PCC composite filler. Two different dissolution mediums, hydrochloric and acetic acid, for chitosan have been seen to affect PCC crystals. Commercial PCC comprises mostly aragonite polymorphs along with some calcite crystals as implied by FTIR, XRD and FE-SEM images. It is interesting to note that surface treatment of PCC with 4.5% chitosan can successfully induce crystal transformation of PCC from aragonite to calcite polymorphs. Further, the deposition of chitosan was estimated from TOC measurements and the presence of deposited amount was validated from TGA analysis. Moreover, the introduction of chitosan (dissolved in HCl) to PCC dispersion was found to raise the zeta potential from − 14.43 to − 11.3 mv. Finally, the tensile strength of handsheets increased by 8.2% with 20% enhancement in ash with chitosan/PCC composite filler compared to the unmodified PCC. Therefore, bio-based PCC composites which proved to be promising for the development of high ash paper without compromising essential properties may result in saving wood pulp and production cost. Thus, implementing such seafood waste as a value-added additive is beneficial both to the industries and the environment because of its biodegradability and eco-friendliness. Keywords Encapsulation · Modified fillers · Papermaking · Phase transformation · Precipitated calcium carbonate

1 Introduction Recent trends of substituting non-renewable petroleumbased resources with renewable have attracted papermaking industries in developing value-added sustainable and biodegradable products. Therefore, both wood and agro residues derived ligno-cellulosic feed-stocks are utilized to produce paper-based materials containing three-dimensional cellulose networks. Though high strength paper can be achieved with 100% load-bearing cellulose fibers, substituting these fiber factions with mineral fillers is a common strategy to reduce the cost and energy associated

with papermaking. The most naturally occurring mineral fillers include clay, talc, ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) which are added to furnish prior to the headbox section in a conventional papermaking process. Among these fillers, PCC has gained a lot of attention worldwide due to its manufacturing flexibility with controllable chemical and physical properties and unique crystal habits. The application of fillers contributes certain functional properties to the sheet such as dimensional stability, light scattering efficiency, printability and writability [1]. These desired characteristics of the sheets are determined by critical parameters

* Chhaya Sharma, chhaya1964@rediffmail.com | 1Department of Paper Technology, IIT Roorkee, Saharanpur Campus, Saharanpur, Uttarpradesh 247001, India. 2Central Pulp and Paper Research Institute, Saharanpur, Uttarpradesh 247001, India. SN Applied Sciences (2020) 2:1577 | https://doi.org/10.1007/s42452-020-03313-w

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SN Applied Sciences (2020) 2:1577 | https://doi.org/10.1007/s42452-020-03313-w

including shape, particle size distribution, aspect ratio, average particle size, aggregate size and density during the manufacturing of fillers. It was found that the smallest particles are detrimental to the paper strength at constant shape. However, the size of PCC is comparatively smaller than that of cellulose fibers resulting in poorer first-pass ash retention in the wire section [1, 2]. Furthermore, the traditional route of stochastic incorporation of fillers in the cellulose network weakens the fiber–fiber bonding at high filler addition level as they may partially reside at fiber interstice which deteriorates the ultimate strength of individual fibers as well as paper. Since papermakers crave for high ash content paper, different classical routes were explored in integrating these pigment fillers with pulp fibers [2–6]. Pre-flocculation or surface modification of PCC through coating or encapsulation among preceding techniques has been an impressive approach to mitigate negative effects on mechanical properties of paper at high ash level [2–4, 7]. Industrial low-cost native starch or cationic starch is a widely accepted biopolymer in filler modification among various researchers as this hydrogen bonding polymer can develop strong bonds with pulp fibers when dried after starch/mineral composite fillers are added to the furnish. Another approach to fabricate these bio-based composite fillers with paper sheet is in situ crystallization of calcium carbonate in the presence of biopolymers [8]. But there are certain limitations associated with starch such as consumption of extra chemicals during the coating process, loss of cationicity at alkaline pH, sensitivity to water and its prone to microbial attack [9]. In addition to starch, several other synthetic or biodegradable polymers were considered for filler modification by adsorbing these polyelectrolytes onto them to confer the enhanced bonding ability between fillers and fibers. Thus, polymerinduced aggregation leads to a larger particle size of the composite fillers which can then be sufficiently retained in the sheet. In paper technology, synthetic polymeric materials are vastly applied as retention and strength aids [10, 11]. Processing with such synthetic polymers results in environmental pollution, serious health issues due to their carcinogenicity and creates problems in recycling or composting paper materials reported by consumers and government bodies. This might have motivated researchers to look for an alternate approach to utilizing biodegradable resources. Since the processing of crustaceans in the seafood industries constitutes 60% of shell waste according to Environmental Protection Agency (EPA), it should be a major concern for the industries to look for solid waste management. Hence, interest lies in the extraction of value-added products from such wastes and their potential application in diverse fields [9, 12, 13]. Chitosan is that biogenic environmental-friendly polymer having natural cationic charge density, biodegradability, Vol:.(1234567890)

non-toxicity, antibacterial and antifungal properties. Not only in medical science and other sectors, chitosan has also emerged as a value-added potential additive among paper industries. Although expensive compared to conventional wet-end additives, its unique property of flocculation ability both at acidic and alkaline pH makes it a better retention-drainage aid in stock preparation [14–16]. In contrast to conventional starch, 30% faster drainage rates, higher internal bond strength, wet/dry strength with no tendency of slime formation, and desired surface and optical properties were notable for chitosan in terms of good machine runnability and energy consumption. It was anticipated that this would minimize the overall cost of production to manufacture an economically feasible paper with high-quality specifications as per customers’ demand [17, 18]. This polymer was found to be effective both for surface coating and wet-end section in developing specialty grade or packaging papers. The NH2 group in the polymer backbone not only provides additional bonding ability with cellulose but also imparts water resistance to the paper when made at alkaline conditions as revealed in these studies. So there is an urge to modify filler surface with this polymer proving possibilities to widen the scope of its application [14, 15, 19]. In the year 2012, a US patent disclosed that PCC’s inherent alkalinity enables chitosan’s precipitation that can effectively functionalize the PCC surface for the development of paper-based composite materials. However, the patent did not reveal either the effect of functionalization on PCC structure or illustrate any mechanism for acidic chitosan-basic PCC reaction [20]. Synthetically produced PCC can exist in three anhydrous polymorphs namely calcite, aragonite and vaterite. Calcite, being the most thermodynamically stable has become a choice to the papermakers. Under different process conditions, it exhibits different morphologies which can be either rhombohedral, scalenohedral or prismatic [3]. Crystallization of calcium carbonate starts with nucleation and crystal growth takes place either by aggregation or by phase transformation mechanism [21]. Thus, crystallization of PCC particles is tailored by manipulating supersaturation, reactant feed, temperature or with some additives to acquire desired properties required for paper [8]. The templating action of many polymers in controlling the calcium carbonate crystal growth and their orientation has been discussed extensively [22–24]. Stabilization of phase, growth rate and ultimate crystal morphology depends on the degree of inorganic/additive interactions. Biomimetic approaches of mineralization show the presence of different polymorphs which can certainly be elucidated by stereochemical complementary between calcium ions and active groups in the polymer chain as well as geometry matching. Chitosan-mediated bio-mineralization has gained a lot of attention and has been observed that

SN Applied Sciences (2020) 2:1577 | https://doi.org/10.1007/s42452-020-03313-w phase transformation is indeed a result of molecular reorganization between polymer and mineral [21, 22]. Many researchers have already evaluated chitosan as a filler modifier for papermaking application but the influence of chitosan on structural changes in PCC during the modification process and their effect on paper properties was given less importance in the reported literature. In the present work, a simple route of integrating chitosan with mineral filler PCC was established for developing chitosan/ PCC composite filler. Detailed characterization of crystal growth and morphology of PCC in the presence of this polymer were stressed so as to evaluate the performance of the corresponding composite as strength and filler retention additive in cellulose integrated paper material.

Research Article

expressed in g. In TOC analyzer, liquid supernatant containing residual chitosan was introduced into the combustion tube which was filled with an oxidation catalyst, generally platinum catalyst and heated to 680 °C. The sample was burnt in the combustion tube and as a result the TC (total carbon) components of the sample were converted into carbon dioxide which was then detected by NDIR (nondispersive infrared) gas analyzer. Similarly, inorganic carbon IC was determined by acidifying the sample to evolve carbon-di-oxide. In both the cases, calibration curves are generated with IC and TC standard solutions to evaluate TOC (TC–IC) of the samples. The obtained filler pellets were then dried at 30 °C for their subsequent characterization

2.3 Characterization of fillers

2 Experimental methods 2.1 Materials Chitosan from shrimp shells with deacetylation > 75% was procured from Hi-media, India. Precipitated Calcium carbonate (PCC) and bleached Hardwood pulp were obtained from Paper mill, India. Hydrochloric acid (HCl) and acetic acid used in the whole study were of analytical grade. The filler suspension slurry was alkaline with pH 10.4.

2.2 Method of preparing modified PCC fillers 1 g of powder filler was dispersed in 50 ml of distilled water with a mechanical stirrer for at least 2 h before modification. 1% chitosan was dissolved in an aqueous solution of 0.1% HCl or 1% acetic acid under constant stirring at 60 °C prior to the experiments [25]. Then, 0.045 g chitosan in solution form was loaded onto the filler slurry followed by mixing for at least 30 min in water bath shaker at room temperature. The polymer percentage calculated on the basis of oven-dried (OD) PCC was 4.5%. No other auxiliary chemical was used to maintain the pH for precipitation of chitosan on PCC particles. After that, the samples were centrifuged at 3000 rpm for 10 min. The supernatant was collected for calculating the sorbed amount of chitosan by analyzing the total organic carbon (TOC) of the samples through the TOC analyzer (TOC-LCPH, Shimadzu). Deposited amount DA was determined by the following equation

DA (%) =

C 1 − C2 × 100 M

(1)

C1 and C2 are the added and residual amounts of chitosan after treatment. M is the mass of PCC. All the units are

The chemical group analysis was done by FTIR (Fourier transform infrared spectrophotometry) through the Perkin Elmer spectrophotometer in a transmission mode conducting 16 scans at a resolution of 4 cm−1 to acquire absorption spectra between 4000 and 500 cm−1. Samples were diluted with KBr (potassium bromide) to form pressed pellets. Further phase transformation phenomenon was studied by examining the crystal structure through WAXD [RIGAKU ULTIMA IV Wide-angle X-ray diffractometer at a scan rate of 4°/min over a range of 2θ = 5°–80°. The operating voltage was 40 kV with a current 30 mA. The radiation source was Nickel filtered CuKα (λ = 1.5406 Å). Next, the thermal stability of modified and unmodified PCC was observed by thermogravimetric analysis (TGA) by TA instrument, USA in a temperature range between 40 and 900 °C at 10 °C/min in a nitrogen atmosphere with 60 ml/min gas flow rate. The weight of the samples varied from 10 to 20 mg. Further, particle size distribution was obtained from the PSD analyzer (LA960, Horiba Ltd., Kyoto, Japan). The principle is based on static light scattering Mie theory. Approximately, 0.1 g of fillers was dispersed in 100 ml distilled water and ultra-sonicated for at least 30 min prior to zeta potential measurements by ZetaPlus zeta potential analyzer (Brookhaven, 205 H2oltsville, NY, USA) [26]. Image analysis of flocs was also carried out by the optical microscope (Motic B1 Series). At first, modified and unmodified filler slurries were diluted to 0.2%, and one drop of the suspension was placed on the glass slides. The glass slides were then air-dried for further investigation. Crystal morphology was examined by TESCAN MIRA 3 Field Emission Scanning Electron Microscope. A very little amount of sample was gold sputtered for 1 min prior to imaging. Images were taken at a magnification of 25 kX, 5kX and 2 kX with an accelerating voltage 10 kV.

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2.4 Handsheet preparation and characterization

3 Results and discussion

Dried pulps were first beaten to a level of 38°SR and then disintegrated at a pulp consistency of 2% for 10 min at 3000 rpm. Pulp slurry was then diluted to 0.4% prior to the addition of unmodified and modified PCCs. The addition level of filler was 15% based on OD pulp. The stock suspension was then mechanically stirred at 400 rpm for 5 min and transferred to a batch laboratory sheet Former so as to achieve a target basis weight of 70 g m−2 according to the TAPPI test method T 205 sp-02. The handsheets were then conditioned in a humidity chamber at 23 °C ± 1 °C and relative humidity 50 ± 2% before testing. For determining the filler retention, ash in the paper was estimated by incinerating paper sheets at 525 °C as per the TAPPI standard method T 211 om-93. Thus, filler retention was calculated from the following equation

Both PCC and modified PCC were characterized by different analytical tools, FTIR, XRD and TGA to detect the chemical groups, phases present in the dried powders and thermal behavior of the composite fillers, respectively. Thus, spectral data obtained from FTIR reveal valuable information regarding the polymorphs of the fillers distinguished by their different carbonate vibration modes. Our commercial PCC comprises mainly aragonite phases assigned by the following carbonate absorption peaks at 1081, 856, 1494, 713 and 700 cm−1. These peaks correspond to symmetric stretching (؆1), out-of-plane bending (؆ 2); doubly degenerate planar asymmetric stretching (؆3) and doubly degenerate planar bending (؆4), respectively. These characteristic peaks of aragonite polymorph have been reported by several researchers [24]. CO32− ions remain inactive in the infra-

Filler retention, FR =

total weight of ash in paper(g) − ash in control(g) × 100 Amount of ﬁller added(g)

Note that control means ash associated with unfilled sheets. Tensile strength was evaluated according to the TAPPI test methods T 494 om-01 by the tensile tester (SE 060, L&W). Other physical properties such as tear and bust were obtained from tear tester (SE009) and burst tester (SE180), respectively. In another experiment, handsheets were subjected to spectrophotometer CM 3630 (Konica Minolta). The morphology of the paper samples incorporated with fillers was analyzed by FE-SEM.

red region and that the band at 1081 cm−1 cannot be seen in the pure calcite phase of calcium carbonate has already been verified in the previous literature [27] [28]. Apart from stretching vibrations, out-of-plane and inplane bending of C-O bond resembling absorption band at 873 and 712 cm−1 are attributed to calcite phases in the sample [28]. The IR spectra of industrially manufactured PCC used in this study have similar absorption bands as per the published literature data revealed from Fig. 1 [29, 30]. The presence of CH and OH species in the unmodified

Fig. 1 FTIR of A Commercial PCC and PCC modified with chitosans and B distinguished peaks of aragonite and calcite

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(2)

SN Applied Sciences (2020) 2:1577 | https://doi.org/10.1007/s42452-020-03313-w PCC depends on various synthesis routes or due to the interaction of some organic additives as dispersing agents during the manufacturing process [30–32]. In comparison to the unmodified one, those modified with chitosan displaying a slight displacement of peak around 1494 cm−1 toward lower absorption band at 1458 cm−1 is due to the differences in the crystal structure of calcite and aragonite. Rather it is assigned to the specific band for calcite [28]. The spectra display a broader peak at 3431 cm−1 mainly assigned to the OH or NH stretching vibrations related to chitosan. Moreover, the absorption band at 2919 and 2874 cm−1 designated for C–H stretch has become broadened due to the overlapping C–H bond associated with chitosan [33, 34]. A weak intensified peak at 1150 cm−1 and a shoulder at 1030 cm−1 could be assigned to an asymmetric stretch of C–O–C bridge and C–O stretch, respectively, revealing the presence of the polymer in the modified samples [34]. Another interesting feature in the modified PCC spectrum observed is that the peaks at 1082 and 856 cm−1 have sufficiently decreased. In fact, a more pronounced peak at 873 cm−1 and disappearance of peak at 700 cm−1 confirms the transformation of aragonite polymorphs to calcite phases. Note that peaks relayed to calcite phases are more intensified when chitosan was dissolved in acetic acid for the modification of the PCC surface. The crystal structure of unmodified and modified PCC was further studied by XRD and shows a good correlation with FTIR data. The coexistence of both calcite and aragonite phases can be detected from the diffraction pattern of pure PCC as noted from Fig. 2. The diffraction peaks positioned at 2θ of 23.0° (112), 29.4° (104), 35.9° (110), 47.5° (018), and 28.5° (116) are associated with calcite polymorph whereas 2θ of 26.2° (111), 27.2° (021), 33.1° (012), 37.9° (112), 38.4° (130), 45.8° (221), 50.3° (132), and 52.5° (023) are related to aragonite phase [35]. After introducing chitosan in PCC dispersion, the intensity of peaks at 2θ = 26.2° and 27.2° corresponding to the planes (111) and (021) of aragonite has been sufficiently reduced with an increase in the peak intensity at 2θ = 29.4° corresponding to (104) planes of calcite. Furthermore, the calcite and aragonite content quantified from respective intensities based on previously reported methods were found to be 21% and 79%, respectively, in the initial PCC sample [36]. On the other hand, chitosan-modified PCC is indexed as a mixture of the majority of calcite with small traces of aragonite. In particular, the dissolution of chitosan in acetic acid and sorption of the polymer on PCC surfaces produce a larger quantity of calcite crystals (97%) compared to hydrochloric acid (92%). The respective aragonite quantity estimated was 3% and 8% [36]. However, traces of chitosan could not be detected from XRD patterns of the modified samples. This can be supported with the earlier reports of XRD where authors did

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Fig. 2 XRD patterns of A PCC, B PCC + chitosan (HCl) and C PCC + chitosan (acetic acid) black filled circle calcite, red filled circle aragonite

not define the presence of chitosan acting as oriented support for the growth of calcium carbonate polymorphs [37]. It was observed that when an acidic solution of chitosan (pH 5.5 in case of both acids) was subjected to the alkaline environment of PCC (pH 10.4), chitosan started precipitating out of the solution resulting in co-aggregation of PCC and polymeric macromolecules with a final solution pH of 7.8–7.9 at equilibrium. The principle of chitosan regeneration in alkaline medium from acidic solution is governed by the screening of electrostatic repulsion between the protonated amine groups above its pKa value [38]. At this stage, the stiff rod-like structure of chitosan conforms more into a random coil followed by deposition on PCC surfaces [39]. Therefore, we have discussed the probable mechanism behind this polymorph transformation by analyzing the data from FTIR and XRD. Generally, calcium carbonate exists in the form of three anhydrous crystal polymorphs among which vaterite is the least stable and calcite being the most thermodynamically stable [40]. The findings from the recent studies suggest that nucleation and growth of resultant crystalline polymorphs (vaterite, aragonite and calcite) occur via dissolution–re-precipitation mechanism through an intermediate hydrated amorphous calcium carbonate (ACC) precursors. [21, 35, 40, 41]. It was inferred that controlling of critical process variables like change of solution pH by acids and organic additives affect the yield of particular crystal polymorphs and its stabilization. pH-dependent dissolution rates of ACC lead to different crystallization pathways that ultimately define a particular calcium carbonate polymorph [42–46]. Ca2+ and Vol.:(0123456789)

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CO3− binding strength and equilibrium carbonate species CO3−/, HCO3− at different pH are the determining factors for ACC structures that mimic certain local polymorphs which further transform into calcite, aragonite or vaterite. The driving force for the conversion of one polymorph to other was postulated to be the HCO3− ions as calcium carbonate growth rate was proportional to the ion activity product of Ca 2+ and HCO3− [47]. On the other hand, chitosan as an additive has been studied as a template for the nucleation and growth of different polymorphic structures based on the charge density and solution pH [21, 22]. This near-neutral macromolecule at alkaline pH was thought to gather Ca2+ ions on its surface providing an interface between this organic–inorganic composite and the surrounding liquid for active nucleation site of calcite crystallization [48]. Therefore, as per our system concerned, the transformation of aragonite crystals to polycrystalline calcite aggregates can be explained on the principle of (1) dissolution–recrystallization mechanism and (2) sorption of chitosan on the crystal surface. In our opinion, the fast dissolution of metastable aragonite at this pH might have released dissolved inorganic HCO3− and Ca2+ ions with coprecipitation of chitosan on aragonite surface [49]. At this point, interaction of chitosan with precipitated calcium carbonate would be difficult to explain since electrostatic forces would not be very strong because of deprotonated amine groups of chitosan in weak alkaline condition [48, 50]. However, chitosan described as a hydrogel in near neutral pH solution could be able to promote calcium carbonate polymorphism. Therefore, we can conclude that chitosan with its amine and OH groups deposited on the crystal surface and served as a template for the recrystallization of calcite aggregates [48]. Inhibition to the

Fig. 3 A TGA and B DTG curves of PCC and chitosan-modified PCC

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growth of free single crystal could be due to the polymeric chains of the macromolecule since it has the ability to form bridges between calcium carbonate particles. Moreover, from the work of Busenberg and Plummer 1987 percentage transformation of more soluble aragonite to the less soluble calcite in contact with water depends on solution pH, solution chemistry, temperature and precipitation time. Various models established for this mechanistic behavior state that the rate of dissolution of primary crystals is equal to the growth of secondary mineral crystals [51]. Several authors have explained that electronegative charge on specific anionic additives likely to adsorb Ca2+ ions which further attracts the HCO3/–CO3− ions to facilitate nucleation of calcium carbonate species [42, 52]. So, in our case, the appearance of a larger number of calcite crystals in the presence of chitosan/acetic acid system may be expected due to an additional effect of this organic acid adsorption on the polymorph rearrangements. Previously, it was observed that carboxylated organic acids with their deprotonated negatively charged sites (COO–) at 7–8 adsorbed on the surface of aragonite crystals inducing their recrystallization to calcite [42]. Although further investigations are necessary to better understand the mechanism of active nucleation pathway to control of rearrangements of PCC polymorphs. The presence of chitosan in the modified PCC was further confirmed by the thermal behavior as observed from TGA-DTG curves in Fig. 3A). Unmodified PCC exhibits single-step degradation profile when the temperature is increased from 40 to 900 °C. This is in agreement with the reported literature [53, 54]. The degradation begins at Tonset = 511 °C and the decomposition completes at temperature 683 °C since this temperature range accelerates the formation of CaO

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and CO2 [32]. In comparison, it is seen that the thermal degradation profile for modified PCCs has changed with two consecutive degradation steps. Besides weight loss due to PCC, an additional weight loss is seen to take place between 210 and 400 °C. This is due to the dehydration of the saccharide ring accompanied by a random chain breakdown favoring complete decomposition of the chitosan molecule [55]. There is no evidence of accompanying curves of OH ions in the DTG graph (Fig. 3B) which further ensures that water is not present in the samples. Moreover, the mass loss for samples PCC + Chitosan (Acetic acid) and PCC + Chitosan (HCl) is around 47% which is relatively higher than the unmodified one whose mass loss was 44% indicating the existence of sorbed bio modifier on PCC surface [56]. Additionally, it is noticeable that though Tonset for calcium carbonate decomposition is almost analogous in all the samples. Maximum weight loss temperature Tmax of modified PCCs deviates from the actual Tmax of the unmodified one as observed from the DTG plot. Tmax for sample PCC, PCC + Chitosan (Acetic acid) and PCC + Chitosan (HCl) is 657 °C, 647 °C and 662 °C, respectively, implying that chitosan precipitated from HCl on PCC surface makes the filler more thermal stable compared to acetic acid. It is possible that acetic acid-mediated less thermal stable composites are attributed to the occurrence of chitosonium acetate originated from residual acids between chitosan chains in the dried composites [57]. The sorption mechanism of chitosan on the PCC surface was then illustrated through the TOC analysis, and the dissolving medium considered was HCl since organic acid from acetic acid interfered with TOC of chitosan as

exhibited in Fig. 4A. There was a significant increment in TOC in the presence of acetic acid as the concentration of chitosan was raised. This initial examination aided us to eliminate the usage of acetic acid since it would be difficult to evaluate the actual concentration of deposited chitosan from the chitosan-acetic acid standard curve. Figure 4B describes the deposition of chitosan onto PCC. Depending on the degree of deacetylation, the intrinsic pKa of chitosan from shrimp is almost close to 6.5 [33]. Hence, the polymer is completely soluble at pH below its pKa value with 90% of its amine group protonated in the glucosamine units [58]. The polymer possesses a cationic behavior in the acidic medium with electrostatic repulsion between its chains [33]. This is in agreement with our result showing that the charge density of chitosan in HCl (pH 5.5) is + 7.3 meq/g. In our study, the high alkalinity of PCC makes the amine group in chitosan deprotonated. The deprotonation means that at pH greater than neutrality chitosan starts becoming insoluble as discussed in previous sections with much of a coiled entangled structure rather than a stiff rod-like structure resulting in significantly higher adsorption on PCC [55]. Similar conclusions were drawn for the adsorption of chitosan on quartz at pH 9 [38]. It is evident from the graph in Fig. 4B that the deposition increases with an increasing amount of chitosan and the maximum value of the deposited amount is found to be 10.7% to reach the saturation level at an added dose of 11% of PCC. When subjected to alkaline pH 10.4 exerted by PCC in CO2 free water, the chitosan might have lost its enough cationic charge to neutralize the colloidal anionic charge on PCC [20]. This hypothesis can be related to our charge density measurement data

Fig. 4 A Total organic carbon (TOC) versus chitosan concentration in 0.1% HCl and 1% acetic acid. B Sorption of chitosan onto PCC at ambient temperature for 30 min when HCl was used as dissolv-

ing medium for chitosan. A Macroscopic optical photographs of unmodified and modified filler slurries taken with a digital camera

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where we could observe that, initially, PCC had an anionic charge density of − 5.49 μeq/g. Even PCC functionalized with 4.5% chitosan, anionic charge density decreased to − 4.4 μeq/g but no charge reversal or charge nullification could be detected at this point. We, therefore, propose that the dominant mechanism was flocculation of PCC by the polymer rather than coagulation. Roussy and Van Vooren observed that solubility and insolubility of chitosan at different pH strongly affects the coagulation/ flocculation behavior of mineral colloids [58]. They concluded that at high pH the neutralized amine groups of polymer chains physically entrap the mineral colloids in its network by bridging mechanism leading to instability of the colloids. Similar trends are also observed in our study. The final pH measured at a chitosan dose of 11% of PCC after adsorption decreased to 7.2. The amount of chitosan on PCC remained almost constant with a further increase in the dose of chitosan. With 4.5% addition of chitosan to PCC, the deposited chitosan amount quantified was 4.3%. An excessive amount of chitosan might have led to re-stabilization of the suspension indicated by the high value of TOC in the supernatant. A similar explanation was given by Roussy and Van Vooren when residual turbidity increased due to excess addition of chitosan for decantation of colloid particles at natural water pH [39]. The increase in the zeta potential of PCC from − 14.3 to − 11.3 mv indicates that adsorbed uncharged chitosan just moved the slip surface of the electrical double layer with some electrostatic interactions. Otherwise, the surface potential of PCC might have been close to zero or reversed [38]. The crystal morphology and surface morphology of the PCC particles were studied by optical microscope and FE-SEM images as depicted in Figs. 5 and 6, respectively. The micrographs obtained under different magnification revealed that aggregated mineral flocs in both modified and unmodified PCC have become dark due to light opaqueness. More aggregated polymorphism was observed with modified one representing surface treatment of PCC either by encapsulation, flocculation, and adsorption/precipitation. Recrystallization of aragonite particles in the presence of chitosan was further examined by FE-SEM. The coexistence of aragonite and calcite is evident from Fig. 6A with a predominance of aragonite crystals in the native PCC. The rod-shaped aragonite crystals are arranged in bundles in a semi-circular structure [43]. As discussed previously in the above sections of the study there are possibilities that interaction between NH2 and OH groups in chitosan with carbonate ions can affect the ultimate crystal habit leading to the formation of a scalenohedral type of calcite in the presence of chitosan [3] [59]. The prevalence of calcite with traces of aragonite is observed in Fig. 6G which can relate well with the increased intensity of Vol:.(1234567890)

Fig. 5 Optical microscopic images (magnification 10X and 40X) of A unmodified PCC. B, C Chitosan-modified PCC. B Represents chitosan dissolved in acetic acid. C Represents chitosan dissolved in HCl

peak corresponding to (104) plane. The aggregation phenomenon can further be corroborated with optical microscope images revealing irregular shaped dense and bigger flocculated particles in modified PCCs. Several other authors reported a morphological change of different grade of fillers preflocculating or modifying with different polymers [6, 14, 60]. The median particle size of native PCC was around 11 μm which increased dramatically to 104 μm after treatment with chitosan when HCl was considered as a dissolution medium. Individual PCC particles were being aggregated to larger flocs in modified PCC through a bridging mechanism by precipitated polymeric chains either as a result of weak electrostatic interaction between chitosan and Ca2+ ions or by physical entrapment of the minerals in its coiled structure. Additionally, Fig. 7 shows that modified PCC exhibits much broader size distribution compared to the native one indicating nonuniform aggregation of filler particles as also observed in FE-SEM images. Similar particle size distribution is not only obtained by papermakers in producing pre-flocculated filler particles [61] but also can be observed in other industries where flocculation is an important mechanism to optimize a system. The encapsulation mechanism is proposed in Fig. 8. As prepared filler slurries were then employed to analyze the effect of chitosan modified filler particles on tensile strength and filler retention calculated from residual ash in handsheets. It is a well-known fact that incorporating filler at high ash level interferes with fiber–fiber bonding resulting in decreased paper strength. Paper strength generally depends on

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Fig. 6 FE-SEM images of unmodified PCC magnified A at 25 kx, B at 5 kx and C at 2 kx. Chitosan-modified PCC magnified D at 25 kx E at 5 kx and F at 2 kx, D–F represent chitosan dissolved in acetic acid. Chitosan-modified PCC magnified G at 25 kx, H at 5 kx and I at 2 kx, G–I represent chitosan dissolved in HCl

Fig. 7 Particle size distribution of A unmodified PCC, B Chitosanmodified PCC. B Represents chitosan dissolved in HCl

individual fiber strength, inter-fiber contact area as well as bonding strength. Figure 9A reveals that at 15% filler dose, the tensile strength of paper decreases by 21% in the case of unmodified fillers compared to unfilled paper. This finding is in consistent with the reported works [4]. Interestingly,

handsheets fabricated with chitosan-induced aggregated fillers are seen to improve tensile strength by 8.2% compared to native ones. Enhancement or negative impact of paper strength with different pre-flocs or bio-based composite mineral fillers is well verified by many authors [4, 8, 60]. According to our proposed mechanism instead of depositing on one single particle, chitosan seems to encapsulate several particles bounded to one another and enmeshed within the polymer chains. When mixed with pulp, amine groups (NH2) of chitosan protruding from the surface of modified PCC establish hydrogen bonds with the cellulose fibers, thereby increasing in paper strength when dried. A similar trend for bursting strength of handsheets can be observed in the case of modified filler as evident in Fig. 10A. Higher improvement in tensile and burst with their corresponding correlation was reported by many while applying functionalized polymers in filler modification technology to achieve higher ash content [14, 60, 62]. Therefore, it is expected that the bonding potential of chitosan may be superior when it is anchored on the surface of PCC fillers rather than stochastically distributed between fibers and fillers. However, papers containing Vol.:(0123456789)

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Fig. 8 Schematic representation of encapsulation of PCC with chitosan

Fig. 9 A Tensile index, B Ash and filler retention of unfilled, filled and modified filler at 15% filler dose based on OD pulp. MPCC represents modified PCC

modified PCC exhibit almost the same tear index noticed in Fig.Â 10A. Though authors have not emphasized much on the behavior of tear strength of paper while using chitosan as a filler modifier [14, 19], a similar effect was Vol:.(1234567890)

observed when PCC-cellulose hybrid composites were incorporated in sheet [63]. On the other hand, at the same ash level, filler retention of unmodified and modified PCC calculated is 38% and 50%, respectively. It is commonly

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Fig. 10 A Optical properties, B tear, burst and apparent density of unfilled, filled and modified filler at 15% filler dose based on OD pulp. MPCC represents modified PCC

known that the filler retention depends upon its particle size, shape and chemical nature. Therefore, higher retention achieved with the aggregated PCC particles may be due to the larger floc sizes. Presumably, a slight decrease in surface potential of PCC may allow the chitosan to adsorb on cellulose fibers effectively ensuring higher retention of modified fillers [60]. It is worth noting that the ash level studied under the experimental conditions does not have a significant impact on the optical properties of the paper in case of modified filler as seen in Fig.Â 10B. However, one can expect that the marginal increase in brightness around 1% at higher ash level is due to higher retention of larger particles of modified PCC [15]. Further, an increase in filler retention as a result of successful surface encapsulation of

PCC with chitosan polymer is evident from Fig.Â 11 which shows networks of cellulose fibers incorporated with mineral fillers. Clearly, SEM analysis reveals that modified PCC not only fills the voids but also creates linkages between fibers by adsorbing sufficiently onto them. This signifies the inevitable adhesive nature of chitosan and its promising end-use application in papermaking.

3.1 An outlook forÂ production cost Approximately, the cost of cellulose pulp (CP) is INR 65/kg (1 USD = INR 75) and PCC is INR 14/kg. Therefore, the estimated cost of base/raw materials for manufacturing PCCfilled paper shall be INR 67100/t considering PCC charge

Fig. 11 FE-SEM images of cellulose networks filled with A unmodified fillers, B modified fillers

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of 150 kg/t of CP and that of for manufacturing modified PCC-filled paper shall be INR 71150/t when 6.70 kg chitosan was applied per tonne of CP for PCC modification. The cost of chitosan is roughly around INR 600/kg. It was found in this study that even such a low dose of chitosan consumed for PCC modification can able to increase PCC retention in pulp fibers by 20% compared to the paper filled with unmodified PCC. It is to be also noted that an increase in ash content reduced the tensile strength loss without mitigating other physical, structural and optical properties. Therefore, replacing cellulose fiber with a higher amount of PCC can be expected to have faster drainage rates and lower energy consumption in paper machines, thus minimizing the overall cost of production. Furthermore, chitosan in its native state was enough to induce PCC flocculation at alkaline pH and function as a potential retention aid without any additional auxiliary chemicals or quarternization. Nevertheless, its utilization from shrimp waste in filler modification technology provides new opportunities for the development of sustainable and eco-friendly products. Overall, a 6% increase in base/raw materials cost with chitosan biopolymer shall be compensated with reduced energy cost in production lines, its value addition to the paper products and its subsequent eco-friendly environmental impact at industrial scale.

4 Conclusions In the present work, an attempt was made to modify the precipitated calcium carbonate (PCC) with chitosan. The notable change in the crystal structure morphology was observed by FTIR, XRD and FE-SEM, respectively. The principle of transition from aragonite crystals from native PCC to prismatic calcite crystals of modified PCC may be proposed based on the dissolution–recrystallization mechanism in the presence of chitosan that leads to stabilization and orientation of polymorphs, thus altering the ultimate crystal habit. Presumably, the polymer acts as a template for the growth of polycrystalline calcites by adsorbing on the surface of aragonite and facilitates bridging of calcium carbonate particle with its coiled like chains. Moreover, the higher intensity at 2θ = 29.4° corresponding to (104) plane of the XRD pattern in case of PCC modified with chitosan dissolved in acetic acid implies a higher fraction of calcite compared to HCl used as dissolving medium. Chitosaninduced aggregation of PCC fillers observed under optical images and FE-SEM was well corroborated to the particle size distribution data. The existence of chitosan chains in modified PCC was confirmed by TGA and TOC analysis. The deposition efficiency of chitosan was above 90% as correlated with measured TOC values. When incorporated Vol:.(1234567890)

with pulp fibers, these polysaccharide/mineral composites showed enhanced filler retention compared to the unmodified one without negatively affecting the physical strength of paper. However, at present ash level, optical properties did not significantly change. Thus, the comprehensive characterization of the composite filler in accordance with our study may be beneficial for the development of high ash paper with desired properties. Such practice of converting seafood wastes into value-added additives are favorable not only to the paper industries but also to the environment leading to an efficient approach to reduce exploitation of forest resources and improve waste management. Further, work related to the factors governing the phase transformation of PCC polymorphs should be thoroughly studied in the future. Acknowledgement The research grant for the present work was supported by the Ministry of Human Resource Development (MHRD), Government of India.

Compliance with ethical standards Conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Synthesis and Application of a Cationic Polyamine as Yankee Dryer Coating Agent for the Tissue Paper-Making Process Cesar Valencia (1), Yamid Valencia (1), and Carlos David Grande Tovar (2). Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the paper to the Yankee dryer (creping cylinder) in paper manufacture. Nevertheless, these resins are highly cationic and they normally adhere in excess to the paper which negatively affects the creping process and the quality of the paper. For this reason, a low cationic polyamine-epichlorohydrin coating (Polycoat 38®) was synthesized from a diamine supplied by Disproquin S.A.S. and epichlorohydrin. The analysis of the synthesized polymer was carried out by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR). The molecular weight of the polymer was obtained by gel permeation chromatography (GPC), physical-chemical properties such as kinematic viscosity, percentage of solids, density, charge density were measured and compared with a commercial PAE resin (Dispro620®) Thermal stability of the Polycoat 38® and glass transition temperature in presence of a release agent (Disprosol 17®) were also evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Finally, a peel adhesion test and an absorption durability assessment were carried out together with the evaluation of the creeping efficiency of the paper by caliper and tensile measurements in a tissue (towel paper) production plant, demonstrating a superior performance in the paper creping process as compared to some commercially available products. Contact information: 1: Área de Investigación, Desarrollo e Innovación, Disproquin S.A.S., Calle 93 Número 7u-2a, Vía CaliJuanchito 760021, Colombia; 2: Grupo de Investigación de Fotoquímica y Fotobiología, Universidad del Atlántico, Carrera 30 Número 849, Puerto Colombia 081008, Colombia. Polymers 2020, 12, 173; doi:10.3390/polym12010173 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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Article 8 – Tissue Yankee Coating

polymers Article

Synthesis and Application of a Cationic Polyamine as Yankee Dryer Coating Agent for the Tissue Paper-Making Process Cesar Valencia 1 , Yamid Valencia 1 and Carlos David Grande Tovar 2, * 1

Área de Investigación, Desarrollo e Innovación, Disproquin S.A.S., Calle 93 Número 7u-2a, Vía Cali-Juanchito 760021, Colombia; analista.id2@disproquin.com.co (C.V.); analista.id@disproquin.com.co (Y.V.) Grupo de Investigación de Fotoquímica y Fotobiología, Universidad del Atlántico, Carrera 30 Número 8-49, Puerto Colombia 081008, Colombia Correspondence: carlosgrande@mail.uniatlantico.edu.co

Received: 25 November 2019; Accepted: 6 January 2020; Published: 9 January 2020

Abstract: Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the paper to the yankee dryer (creping cylinder) in paper manufacture. Nevertheless, these resins are highly cationic and they normally adhere in excess to the paper which negatively affects the creping process and the quality of the paper. For this reason, a low cationic polyamine-epichlorohydrin coating (Polycoat 38® ) was synthesized from a diamine supplied by Disproquin S.A.S. and epichlorohydrin. The analysis of the synthesized polymer was carried out by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1 H-NMR). The molecular weight of the polymer was obtained by gel permeation chromatography (GPC), physical-chemical properties such as kinematic viscosity, percentage of solids, density, charge density were measured and compared with a commercial PAE resin (Dispro620® ) Thermal stability of the Polycoat 38® and glass transition temperature in presence of a release agent (Disprosol 17® ) were also evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Finally, a peel adhesion test and an absorption durability assessment were carried out together with the evaluation of the creeping efficiency of the paper by caliber and tensile measurements in a tissue (towel paper) production plant, demonstrating a superior performance in the paper creping process as compared to some commercially available products. Keywords: coating agent; paper creping; polyamine-epichlorohydrin resin; release agent; yankee dryer

1. Introduction Coatings are adhesive compounds which facilitate the operation of the creping machines since they allow the paper to adhere to the yankee dryer’s surface at the last step of the tissue paper conversion [1]. These are used in conjunction with a release agent that controls the hardness of the coating and its adhesion, allowing the demolding of the paper once in contact with the creping blade as shown in Figure 1 [1]. Coating agents commercially available, such as Discrepel HRC® , Kymene 557H® , Rezosol 8223® , and others [2], are synthesized from various available additives, such as polyamine-amide resins mixed with polyvinyl alcohols and ethoxylated alcohols [2]. Unfortunately, they tend to develop less re-wettable hard coatings due to the high cationic charge of the polymer [3,4]. The described Polymers 2020, 12, 173; doi:10.3390/polym12010173

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situation causes a strong adhesion and blade vibrations, which in turn generates non-uniform creping and proﬁle of the paper, blade wear, and damage to the surface of the drying cylinder [5]. On the other hand, the most common release agents usually have the combination of fatty alcohols, glycerol, and non-ionic emulsifying agents such as lecithin [6,7].

Figure 1. Scheme of the creping process using a coating-release agent in the yankee dryer.

The main limitation is that all the components must be completely emulsified along with the coating in the yankee’s surface during application since the hardness and adhesiveness should be equilibrated depending on the needs [7,8]. The previous requirement implies that during the application the emulsions must be stable and homogeneous, which normally does not occur when the most common release agents are used [8]. In general, these types of emulsions are easily separated and their application in the yankee leads, for example, to non-homogeneous coating, which is traumatic for the drying process affecting the formation of the tissue paper rolls and also yankee’s surface could be deteriorated [5,7]. The shelf-life of the doctor creping blade could be reduced and the different adherence intensity to the paper sheet deteriorates its creping process and the final quality of the paper [5,7]. Therefore, there is a great demand for a crepe coating-release couple that remains soft and re-wettable under the drying conditions found in creping [1,7]. It is necessary that produces high creping efficiency while generating a high-quality paper [9], less creping blade wear, and greater protection for the yankee to generate a uniform release of the paper and that does not produce bursting problems on paper rolls [7]. Promising coatings that seems to accomplish these requirements are the polyamine-based resins. These resins show charge density and structures related to the fibers of the pulp which generates lower dry strength in the paper than the classical PAE [10,11]. In addition, they have less adhesion and hardness properties, controllable during the polymerization process [12] in order to have properties required by the yankee [5]. At the same time, release agents based on vegetal oil surfactants present stable emulsions that control this type of coatings once they are applied to the yankee [13,14], which inspire us for the present development. For this reason, a new coating (Polycoat 38® ) was designed based on a diamine and epichlorohydrin [15] to generate a cationic polyamine whose structure, viscosity, percentage of solids, charge density, and tensile measures indicates a greater adhesion-release balance. Therefore, greater rewetting properties together with the interaction of a mineral oil-based release agent (Disprosol 17® ), allows a more stable coating on the yankee [1], with high resistance, greater smoothness, and a better absorbency of the paper while the creping took place at a paper mill of a tissue production plant [5,7,8].

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2. Materials and Methods 2.1. Materials All the reagents used in this research (U.S.P grade) were obtained from Sigma-Aldrich (Palo Alto, CA, USA) and used without further purification unless otherwise stated. 2.2. Synthesis of the Polyamine Resin Polycoat 38® Polycoat 38® , which is a polyamine obtained by the A. Allen modified method [15], uses a difunctional polyamine or diamine with epichlorohydrin for the polymer synthesis with the addition of polyvinyl alcohol between 25–60 ◦ C, and it is advantageous providing strong adhesion of the cellulosic fiber web to the dryer surface during the creping process to attain a soft, bulky tissue paper web [15,16]. The diamine was placed in a 100 kg industrial pilot reactor with double jacket coupled to a steam and a water recirculatory ice bank (Disproquin S.A.S., Candelaria, Colombia). Aqueduct water was added to the pilot in order to reach 38 wt % solids. It was then heated to 50 ◦ C and stirred. A sample of 8.50 kg of epichlorohydrin were slowly added at room temperature with agitation. The exothermic reaction reached a temperature of 150 ◦ C and it was stirred for 4 h. Finally, when a kinematic viscosity between 400 and 500 cP was reached, a solution of 0.1% sulfuric acid was added to stop the reaction. The resultant polyamine cationic product was stored in plastic drums [4,15–18]. 2.3. Characterization 2.3.1. Characterization of the Polycoat 38® FTIR measurements were performed on an infrared equipment, Thermo brand model NIcolet 6700 (ThermoFisher Scientific, Waltham, MA, USA), using KBr tablets. 1 H-NMR measurements were performed on a 400 MHz NMR Bruker Ultra Shield (Bruker Corporation, Billerica, MA, USA) using D2 O as a solvent. GPC measurements for the molecular weight determination of the polymer were performed using a gel permeation chromatograph Agilent 1200 (Agilent Technologies, Santa Clara, CA, USA) with 2 intercrossed polymer columns Shodex ohpak (Showa Denko, Tokyo, Japan) as the stationary phase and NaNO3 0.15 M /HCOOH 0.5 M as the mobile phase, using pullulan standards for the calibration curve and a refractive index detector. Thermogravimetric analysis was performed on a TGA-2050 thermogravimetric analyzer (TA instrument, New Castle, DE, USA) adjusted in a working temperature range between 25–400 ◦ C. DSC measurements were made in a DSCQ 100 (TA instrument, New Castle, DE, USA). The ion demand of the resin was measured with an automatic particle charge analyzer (AFG Analytic GMBH, Leipzig, Germany). The non-volatile percentage was calculated using Equation (1). %Solids = W f /W i (1) where W i was the initial weight of the sample and W f was the final weight after heating at 105 ◦ C during one hour in an oven (Memmert Gmbh + Co. KG, Buchenbach, Germany). The kinematic viscosity was measured to 500 g of the sample, using the needle 1 at 50 RPM and the respective Brookfield RVT viscometer (Brookfield Engineering Laboratories Inc., Middleborough, MA, USA). The density was calculated by weighing 1.000 mL of the sample, added with a micropipette (Eppendorf, Hamburg, Germany). The pH was measured with a Hanna pH meter (Hanna Instruments Inc., Woonsocket, RI, USA). Peel adhesion test of the coating was carried out with a horizontal tensile tester ZB-WL30 (Hangzhou Zhibang Automation Technology Co., Ltd., Zhejiang, China) to tissue hand-sheets with 30 g/m2 grammage, 5.5 cm long and 1.5 cm with, attached to a standardized aluminum panel 9.5 cm long and 1.5 cm width. In the procedure, 0.04 mL of the coating is added to the panel and spread with a bronze applicator. The paper is adhered to the panel at 105 ◦ C in an oven (Memmert Gmbh + Co. KG, Buchenbach, Germany) and its exposed edge is tightened with the tensile clamp, which removes the strip at a speed of 10 mm/min and records the force required to detach it [2]. Finally,

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the coating durability was evaluated by the degree of swelling and erosion [5], where the coating was immersed in distilled water at room temperature. After 24 h, the coating was ﬁltered, the water residues were dried with ﬁlter paper and wet weighted, the sample was put in an oven (Memmert Gmbh + Co. KG, Buchenbach, Germany) for 24 h at 37 ◦ C. Its dry weight was recorded and the following Equation (2) was used for the calculation. %Erosion = ((W i − W f )/(W i )) × 100

(2)

where W i is the wet weight and W f is the ﬁnal dry weight. 2.3.2. Characterization of the Tissue Creping Paper The hand sheets for the analysis of the paper were obtained folding 16 times a 2.65 m2 sheet of a paper roll which is then cut using an Alfa pneumatic precision cutter (Thwing-Albert Instruments Company, West Berlin, NJ, USA). As a result, 16 sheets whit 22.5 cm2 area and grammage between 14.5 and 15.5 g/m2 were obtained. Caliber of the 16 sheets was measured with a digital micrometer (testing machines Inc., Las Vegas, NV, USA). Tensile strength and elongation of 8 sheets in machine direction (MD) and 8 in cross machine direction (CD) were measured using a QC-1000 Tensile Tester (Thwing-Albert Instruments Company, West Berlin, NJ, USA). 2.4. Application of the Polycoat 38® and the Disprosol 17® in the Yankee Dryer Both products were added trough a shower at 35 psi using two dosing pumps, the Polycoat 38 and the Disprosol 17® where dosed with a 1.4:2 ratio to a 2.65 m wide and 5.2 m diameter yankee dryer working at a speed of 400 m/min, with internal steam pressure of 112 psi and an external temperature of 105 ◦ C, where the doctor creping blade exerts a pressure of 45 psi on the product which allows 14.5–15.5 g/m2 grammage paper rolls with weights between 950–1150 kg to be produced at a speed of 336 m/min, leading to the fabrication of triple sheet towels in a Colombian toilet paper manufacturing company. Creping and cleaning blades wear were measured using a digital microscope camera (Microview Science and Technology Co., Ltd., Beijing, China). To complement the previous information, a graphical abstract of the methodology used from the coating synthesis to its application in the paper mill can be observed in the Figure 2.

Figure 2. Graphical abstract of the synthesis and application of the Polycoat 38® coating in the yankee dryer.

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3. Results and Discussion 3.1. FTIR Analysis of the Polycoat 38® Resin The FTIR spectrum of the polymer resin is presented in Figure 3. The characteristic bands of the cationic polyamine [10,19,20] are observed. At 3311 cm−1 the broad tension vibration band of the O–H bond is observed. The band at 1070 cm−1 corresponds to the C–O bond in the C–OH group that allows the interaction with the ﬁber and that is part of the azetidine ring [21]. On the other hand, at 1218 cm−1 is the tension band of the C–N bond presented in the quaternary nitrogen of the azetidine ring [10], also, the vibration band of the N–H caused by the interaction between the added acid and the groups of free amines appears in 1623 cm−1 [15] Finally, at 2946 cm−1 , the C–H tension vibration band of the methylene groups in the main chain of the polymer is observed [22].

Figure 3. Fourier transform infrared spectroscopy (FTIR) spectrum of the polyamine (Polycoat 38® ) resin synthesized.

3.2. 1 H-NMR Analysis of the Polycoat 38® Resin In the 1 H-NMR spectrum (Figure 4), the characteristic signals of the protons presented in the coating resin can be observed [23,25]. The signals at chemical shifts of 0.96 and 1.66 ppm correspond to the protons of the CH2 and CH groups of the azetidine ring, where quaternary nitrogen are generated and relate with OH groups at the end of the ring [25]. These OH groups tend to form hydrogen bonds with the cellulose and hemicellulose (polyoses) allowing the adhesion of the paper to the yankee and a posterior detachment once it comes into contact with the creping blade [24]. On the other hand, the multiplet presented between 2.89 and 3.04 ppm are characteristic of the protons presented in the CH groups of the main polymer backbone [4,25].

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Figure 4. Nuclear magnetic resonance (1 H-NMR) spectrum of the polyamine (Polycoat 38® ) resin synthesized.

Finally, a signal from the NH and the OH protons of the chain would be expected around 8 ppm. However, the signal is not observed due to the presence of the deuterated solvent that causes an exchange of protons with the hydrogens of this groups and decreases the intensity of the signals [25]. The ﬁgure also shows the possible structure of the cationic polymer and its corresponding azetidine ring [4]. 3.3. Molecular Weight Determination of the Polycoat 38® Resin The molecular weight of the resin was calculated using gel permeation chromatography technique. Retention time of the peak corresponding to the polyamine yield an average molecular weight (Mw) of 3131 g/mol and an average number molecular weight (Mn) of 2890 g/mol. Mw was higher since it corresponds to higher molecular weight chains, while Mn is sensitive to low molecular weight chains [22]. On the other hand, these values allowed to elucidate the polydispersity index (PI), which in this case corresponded to 1.08. This value is close to the unit and indicates that the lengths of the chains are practically equal [26]. That will produce a homogeneous distribution on the surface of the yankee, which in turn will generate an optimal contact with the sheet of paper to crepe without the presence of holes caused by spaces between chains of high and low molecular weight [27]. Likewise, the distribution of the cations across the polymer are uniform decreasing the residual epichlorohydrin of the synthetized resin which is an environmental requirement for these processes [28].

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3.4. Thermogravimetric Analysis (TGA) of the Polycoat 38® Resin Figure 5 shows the weight loss of the polymer in function of the temperature. The first loss is due to the amount of water retained in the interstices of the polymer which tend to evaporate between 45 and 100 ◦ C [29]. The second loss is observed between 351 and 378 ◦ C, corresponding to the rupture of the main chains in the polymer, leading to its degradation [25]. The given temperature is higher than the working temperature of the surface of the yankee [5], which indicates that there will be no problems due to the deterioration and subsequent breakage of the main chains of the polymer and the opening of the azetidine rings [5], needed to adhere the paper through OH cellulose groups on the yankee’s surface [30].This indicates that a loss of durability of the coating will not be present since the yankee surface temperature is lesser than the coating degradation temperature [5], meaning that the coating performance will not be affected, so loss of bulk in the finished paper rolls and cross machine direction profile issues of uniformity in the produced paper roll will not be observed [7].

Figure 5. Thermogravimetric analysis of the polyamine (Polycoat 38® ) resin synthesized.

3.5. Differential Scanning Calorimetry (DSC) of the PAE Resin The differential scanning calorimetry analysis is of utmost importance because it shows the vitreous transition temperatures (Tg ) of the resin [31]. The value of Tg on the central axis is between the range in which the behavior of the polymer is between glassy and rubbery [31]. The Tg needs to be greater than the yankee working temperature, otherwise the coating will not be soft enough to prevent blade chattering [5,7], wearing it out and producing a direct contact with the yankee by loss of thickness of the coating layer and a “smooth” crepe with more space between the crepe pockets [5]. In this case, the temperature of the yankee where the product was proven exceeded 100 ◦ C and it can be seen in Figure 6 that the Tg of the coating alone and emulsified with release in a proportion similar to that used in the yankee were 85.7 and 77.7 ◦ C, in which the polymer behaves like a thermoplastic rubber and is soft enough to produce high quality paper [31]. This DSC behavior was similar to other polyamide-based resins as reported by Huang K. et al. [32].

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(a)

(b)

Figure 6. Diﬀerential scanning calorimetry (DSC) analysis of (a) the polycoat 38® resin synthetized and (b) emulsion of polycoat 38® and Disprosol 17® .

It should be noted that each yankee operates at diﬀerent temperatures depending on the requirements of the paper mill. If a slightly lower temperature is required, then the coating Tg should be slightly reduced by the addition of the release in a controlled way. For this reason, it is preferable that the temperature range of the product is not so wide in order to easily achieve subtle changes in the Tg of the polymer when it is required [31,33].

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This behavior is observed in Figure 6 where the addition of Disprosol 17® to the coating decreases the Tg values slightly by increasing the softening of the chemical duple which was evidenced on the brittle property of the polymer under this temperature, generating a high adhesion coating that can be easily coupled to yankee dryers working at lower temperatures [33]. 3.6. Relative Adhesion of Polycoat 38® The relative adhesion of the coating was measured by the peel adhesive method [2,5] and although the peel produced is not similar to that of a crepe blade, it is possible to measure the force required to release the paper without breaking it [2]. In the procedure, the metallic surface of the yankee is simulated at 105 ◦ C by a metal panel at the same temperature covered with coating and attached to a low grammage tissue paper in order to compare the Polycoat 38® with other commercial coatings [2,5,15]. Table 1 shows the results of relative adhesion of diﬀerent coatings together with Polycoat 38® . Table 1. Relative adhesion of diﬀerent coatings commercially available. Coating

Relative Adhesion (gF/3in)

Dispro620®

PAE Discrepel HRC® Glyoxilated Polydadmac Polycoat 38® Polycoat 38:Disprosol 17® (1:1,4) CR180®

2823 1595 1179 1078 966 N/A

N/A: No adhesion.

As observed in Table 1, the adhesion of the Polycoat 38® is lower than a PAE such as Dispro620® [12], a high adhesion can lead to paper tearing during production because the tensile force required to tear paper of grammage 15 g/m2 in general, is close to 600–1000 gF/3in, which is a value far below than the given by the PAE. Likewise, other polymer-based coatings such® as Polydadmac or Discrepel HRC® can be highly cationic, which generate a strong adhesion of the paper to the yankee so that during their addition, a large amount of release would have to be added and thus decrease the adhesion but increase costs [10,11]. Adding for example, Disprosol 17® to the Polycoat 38® , we observed a decrease of 10% in the adhesion of the coating, which apparently resembles more the dry strength of low grammage paper. Thus, it was possible to balance the adhesiveness of the coating on the yankee as reﬂected during the application and production of the paper [7,8]. 3.7. Durability Test of the Polycoat 38® The swelling erosion test of Polycoat 38® showed a polymer degradation of 95.9% after 24 h when comparing the initial swollen weight and the dry weight at 37 ◦ C using Equation (1) [5]. To evaluate the rewetting of the polymer, the time that takes for the yankee to rotate 360◦ was used since it is the time in which another layer of coating is sprayed again [3]. This time value was equivalent to 0.26 s and was obtained from the data provided in Section 2.4. Using the result of the erosion of the polymer in 24 h and the yankee rotation time, a value of 0.0003% loss of durability during one yankee rotation was obtained. This result is practically negligible and means that there would not be degradation caused by humidity during the Polycoat 38® uses [4,5]. 3.8. Quality Parameters of the Polycoat 38 Resin and Disprosol 17 Release Agent Physicochemical properties of the coating and the release agents were determined according to the quality requirements of both products and are presented in Table 2.

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Table 2. Quality parameters of the Coating (Polycoat 38) and the release agent (Disprosol 17). Parameter

Polycoat 38®

Disprosol 17®

Appearance Color pH Viscosity Total solids Density Charge density Dispersion

Liquid Ambar 3.00–5.00 <600 cP 38.00% 1.01–1.03 g/mL 1800 mEq/L N/A

Liquid Ambar 6.00–8.00 <400 cP 100% 0.80–0.90 N/A 100% in water

N/A: Not applied.

The parameters shown in Table 1 provide information for industrial purposes and certain parameters such as pH must be within a range that can affect the performance of the yankee. For example, the water of the tissue paper mills has a relatively neutral pH, so the mixture of both products must be maintained between 5–9 to avoid deterioration in the yankee [34]. On the other hand, other parameters such as the viscosity of the products provide information on the product itself. A high viscosity is related to a lower flexibility of the polymer which may decrease the adhesiveness of the coating [35]. The release agent may be necessary to decrease the viscosity of the final product and its smoothness to achieve a more uniform creping [5,33]. Another important property for this type of cationic polymer-based resin is the charge density. Charge density is related to the percentage of azetidine rings formed in the resin which are those that adhere to the fiber when the paper passes through the yankee [30]. A higher charge indicates greater adhesiveness and although it is a desirable property an excess may cause an excessive paper sticking causing deterioration of the coating when comes in contact with the creping blade [7]. This undesirable property is generally provided by top-charge resins such as PAEs, which have been presenting these problems despite their broad application [3]. When comparing the charge density of a PAE such as Dispro 620® manufactured at Disproquin S.A.S (2700 mEq/L) with Polycoat 38® (1800 mEq/L), it was inferred that there is a bigger amount of azetidinium groups in the PAE compared to the Polycoat 38® . These groups are the reason of the interaction with the fiber [24] and although a good adhesion to the fiber is necessary, an excessively high charge generates a very strong adhesion, which leads to difficulties in the demolding and reduces the creping efficiency [3–5]. For this reason, the use of a PAE was discarded and the application was done with the Polycoat 38® , which generated paper with desirable properties, as explained previously at Section 3.8 [36]. 3.9. Application of the Polycoat 38 Along with Disprosol 17 as Yankee Dryer Coating-Release Agent The interaction of the coating-release agents with the paper and the yankee dryer leads to a complex chemistry that has not been fully developed. In addition, this interaction is affected by multiple process such as changing a felt, a blade, cleaning a mesh or modifying a pick-up pressure [13]. For this reason, measurements of the effectiveness of products at the laboratory level are only approximate and are not necessarily reflected in the application [37]. Therefore, the analysis that is performed during production goes hand in hand with the experience of the operator and the process quality analyst. Thus, the application of the product was done starting at a ratio of 1:1 until reaching a dose of 7 mL/min of Polycoat 38® and 10 mL/min of Disprosol 17® (1:1.4), which allowed an optimal profile of the paper roll in obtaining at a speed of 352 m/min. A balanced profile indicates that there are no bulges in the forming-roll caused by a poor distribution of chemicals or an unstable emulsion or a swelling in the paper. On the other hand, during the application there were no bursts of paper in formation which indicates that there is an optimal adhesiveness generated by the Polycoat 38® and a good relationship

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between this and the release capacity of Disprosol 17® once the paper is creped. In addition, there was little noticeable wear on the creping and cleaning blades as shown in Figure 7.

Figure 7. Creping and cleaning blade wear as a function of time.

As shown in Figure 7, the wear of both blades was minimal and even along their axes (position 1 to 11). In addition, when the creping blade was removed, did not present residue. This shows that the product covers uniformly the surface of the yankee and does not leave residue on the blade that could interfere with creping [5]. On the other hand, the cleaning blade tends to have a slightly higher damage compared to the creping blade since it removes the coating-release residue in the yankee and its pressure against the cylinder is higher. 3.10. Quality Parameters of the Tissue Creping Paper Obtained 3.10.1. Caliber of the Tissue Creping Paper Obtained Caliber is one of the most important properties of tissue paper as it gives a ratio of the thickness of each sheet [38]. This parameter relates to the angle of the ‘pockets’ or ‘crepes’ per unit length [5]. Thus, the paper mill must maintain the caliber of the triple sheet tissue at a value lower than 12.0 mm/100 folds otherwise the creping would be irregular and the produced paper would be rough [38]. Caliber also allows to evaluate the quality of the coating. If caliber remains high throughout the application the adhesiveness of the coating would not be optimal [15], but if it remains low and rises in a short period of time, it would indicate that the hardness of the coating wears very quickly the blade [5]. The addition of the Polycoat-Disprosol agent generated paper with a caliber of 9.4 mm/100 folds. This indicates that the adhesiveness of the Polycoat 38® is of high quality and suggest that the wear of the blade was not representative and allowed to produce soft paper with optimal crepe [14]. 3.10.2. Tensile Strength and Stretch of the Creping Paper Obtained The measurement of the tensile strength of the paper does not allow to measure the efficiency of the coating-release directly, but it does allow to obtain the stretch force in the direction of the machine (MDS) [39]. With this value is possible to obtain the relative efficiency of a coating by using Equation (3) of stretch per creping unit [5], where CE is the relative coating efficiency and %C is the creping percentage, which in turn is obtained using Equation (4) [5]. CE = MDS/%C

(3)

%C = (YS − RS/YS) × 100%

(4)

where YS is the speed of the yankee and RS is the speed of the roll or winding cylinder of paper. When replacing these variables with the speed values given in Section 2.4 a result of 16%C is obtained. This

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%C was used in the Equation (3) along with the MDS which was 22% (calculated with the tensile tester), to obtain the coating efficiency of 1.4 MDS/%C. Nevertheless, this efficiency value does not indicate much if it is not compared with the efficiency of other coatings agents found in the literature. In this case, the efficiency of the Polycoat 38® appears to be 45% higher than other coating systems such as the reported by Archer S. et al. [5] with a value of 0.94 MDS/%C, meaning that Polycoat 38® have the desired behavior of adhesiveness, softness, and durability for a high-quality creped tissue [9,39–41]. 4. Conclusions A polyamine-based resin (Polycoat 38® ) was synthetized by a modified A. Allen method, and was demonstrated to fulfill the requirements as a coating adhesive due to the presence of azetidine groups in its structure which allows interactions with polyoses of creped tissue paper. The presence of these groups was elucidated by FTIR, 1 H-RMN, and charge density analysis. These analyses, together with the GPC and thermogravimetric analysis permitted to know the polymer molecular weight, structure, its thermal stability, and its Tg along with Disprosol 17® (release agent) at the working temperature of a yankee dryer, were the coating-release agent was applied at a ratio of 1:1.4 respectively. The addition of the chemical couple (coating-release) allowed a uniform profile along the paper roll of the tissue paper and minimal wear on the creping and cleaning blades evidenced in the low caliber of the paper and quality parameters. This also relates to the effectiveness of the coating which was 45% higher than others previously reported. Author Contributions: Conceptualization, C.D.G.T.; Formal analysis, C.V.; Investigation, C.D.G.T., Y.V. and C.V.; Methodology, C.D.G.T., Y.V. and C.V.; Project administration, C.D.G.T.; Writing—original draft, C.D.G.T. and C.V.; Writing—review & editing, C.D.G.T. and C.V. All authors have read and agreed to the published version of the manuscript. Funding: This research was founded by DISPROQUIN S.A.S and COLCIENCIAS (Proyecto 64853 convocatoria 786 de beneficio tributario). Acknowledgments: The authors acknowledge the company Colombiana Tissue for allowing the evaluation of the products in their paper mill. Conflicts of Interest: The authors declare no conflict of interest.

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Huang, K.; Xia, J.; Yang, X.; Li, M.; Ding, H. Properties and curing kinetics of C21-based reactive polyamides as epoxy-curing agents derived frpm tung oil. Polym. J. 2010, 42, 51–57. [CrossRef] Thirtha, V.; Lehman, R.; Nosker, T. Effect of Additives on the Composition Dependent Glass Transition Variation in PS/PP Blends. J. Appl. Polym. Sci. 2008, 107, 3987–3992. [CrossRef] McLeay, D.J.; Walden, C.C.; Munro, J.R. Effect of PH on Toxicity of Kraft Pulp and Paper Mill Effluent to Salmonid Fish in Fresh and Seawater. Water Res. 1979, 13, 249–254. [CrossRef] Shah, N.; Mewada, R.K.; Mehta, T. Crosslinking of Starch and Its Effect on Viscosity Behaviour. Rev. Chem. Eng. 2016, 32, 265–270. [CrossRef] Neal, C.W.; Forde-Kohler, L.J. Method for Creping Paper. U.S. Patent 6187138B1, 13 February 2019. Scott, W. Principles of Wet End Chemistry, 1st ed.; Tappi Press: Atlanta, GA, USA, 1996. Carson, C.G.; Popil, R.E. Examining Interrelationships between Caliper, Bending, and Tensile Stiffness of Paper in Testing Validation. TAPPI J. 2008, 7, 17–24. Tissue Sheet Softness—Theory, Measurement, and Chemical Applications Which Can Improve It. Available online: https://www.tissuestory.com/2017/08/31/tissue-sheet-softness-theory-measurement-and-chemicalapplications-which-can-improve-it/ (accessed on 18 October 2019). TAPPI. Tensile Properties Of Paper And Paperboard (Using Constant Rate Of Elongation Apparatus); Technical Association of the Pulp and Paper Industry: Peachtree Corners, GA, USA, 2006; pp. 1–28. Kneller, J.F.; Park, L.G. Cross-Linked Poly(Aminoamides) as Yankee Dryer Adhesiver. U.S. Patent 5382323A, 17 January 1995. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Kinetic analysis about the CO2 capture capacity of lime mud from paper mill in calcium looping process Rongyue Sun (1,2), Rui Xiao (1), Jiangming Ye (2). Lime mud, a kind of industrial waste that produced in paper mill, was proposed as CO2 sorbent in calcium looping process. The carbonation performance of the lime mud was investigated in a dual-fixed bed reactor (DFR) and a thermogravimetric analyser (TGA). The carbonation kinetics of the lime mud in the chemical reaction controlled stage was analyzed by a surface reaction-controlled kinetic model. The results show that the lime mud presents much poorer carbonation performance during the chemical reaction controlled stage compared with the limestone, mainly due to the high content of chlorine in the lime mud. A prewash treatment process was used to decrease the chlorine content to mitigate the sintering of the lime mud when calcined at high temperature. After prewash treatment, the prewashed lime mud shows much higher CO2 capture capacity during the chemical reaction controlled stage compared with the lime mud. A prolonged carbonation process successfully further enhances the microstructure and improves the carbonation performance of the prewashed lime mud in the chemical reaction controlled stage. The lime mud can be effectively used as CO2 sorbent in calcium looping process after prewash treatment and the following prolonged carbonation treatment. Contact information: 1: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing, China; 2: School of Energy and Power Engineering, Nanjing Institute of Technology, Nanjing, China. Energy Sci Eng. 2020;00:1–11. DOI: 10.1002/ese3.792 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Page 1 of 12

Article 9 – Waste Treatment

Received: 6 February 2020

Revised: 28 June 2020

Accepted: 9 July 2020

DOI: 10.1002/ese3.792

RESEARCH ARTICLE

Kinetic analysis about the CO2 capture capacity of lime mud from paper mill in calcium looping process Rongyue Sun1,2

Rui Xiao1

Jiangming Ye2

Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing, China 2 School of Energy and Power Engineering, Nanjing Institute of Technology, Nanjing, China

Correspondence Rongyue Sun and Rui Xiao, Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, No. 2 Sipailou, Nanjing 210096, China. Emails: sunrongyue@163.com; ruixiao@ seu.edu.cn Funding information National Natural Science Foundation of China, Grant/Award Number: 51706094

Abstract Lime mud, a kind of industrial waste that produced in paper mill, was proposed as CO2 sorbent in calcium looping process. The carbonation performance of the lime mud was investigated in a dual-fixed bed reactor (DFR) and a thermogravimetric analyzer (TGA). The carbonation kinetics of the lime mud in the chemical reaction controlled stage was analyzed by a surface reaction-controlled kinetic model. The results show that the lime mud presents much poorer carbonation performance during the chemical reaction controlled stage compared with the limestone, mainly due to the high content of chlorine in the lime mud. A prewash treatment process was used to decrease the chlorine content to mitigate the sintering of the lime mud when calcined at high temperature. After prewash treatment, the prewashed lime mud shows much higher CO2 capture capacity during the chemical reaction controlled stage compared with the lime mud. A prolonged carbonation process successfully further enhances the microstructure and improves the carbonation performance of the prewashed lime mud in the chemical reaction controlled stage. The lime mud can be effectively used as CO2 sorbent in calcium looping process after prewash treatment and the following prolonged carbonation treatment. KEYWORDS

calcium looping process, CO2 capture, kinetics, lime mud

IN TRODUCT I ON

Large amount of industrial wastes are discharged from commercial production every year.1 Lime mud is a kind of industrial waste that produced during the causticization process in paper mill. China is one of the papermaking and paper consumption powerhouses. In China, about 50 million tons of paper was produced every year, which means dozens of million tons of lime mud were discharged to the environment. The discharge of such a large amount of lime mud leads to

serious environmental aspects including water pollution and land occupation.2 Therefore, how to recycle the lime mud in environmentally friendly ways is an interesting topic and has drawn lots of researchers’ attentions. Lime mud was firstly recovered as soil amendments and building materials.3 Qin et al4 have proved that recycling of lime mud as raw materials of anorthite ceramic was a feasible approach to solve the solid wastes. Madrid et al5 successfully reused lime mud to produce concrete masonry units that with better thermal properties. In recent years,

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2020 The Authors. Energy Science & Engineering published by Society of Chemical Industry and John Wiley & Sons Ltd Energy Sci Eng. 2020;00:1–11.

wileyonlinelibrary.com/journal/ese3

lime mud was widely investigated to remove pollutants in different phase and as catalysts in chemical industry. Li et al6 used lime mud to prepare heterogeneous base transesterification catalyst by doping with potassium fluoride, and up to 99% oil conversion can be achieved under the optimum conditions. Lime mud was also investigated to absorb SO2 at fluidized bed conditions.7 The result shows that lime mud exhibits much better SO2 capture capacity compared with limestone due to the beneficial microstructure of the calcined lime mud for SO2 removal. CO2 emission from fossil fuel combustion has been identified as one of the major greenhouse gases and leads to global warming. Since fossil fuel fired power plants are the major sources of CO2 emission, how to capture the CO2 from flue gas in power plant has drawn public attentions.8-10 The reuse of the lime mud in environmentally friendly way and CO2 capture from flue gas can be simultaneously realized if lime mud can be used as CO2 sorbent in carbon capture system. Calcium looping process is widely considered as one of the most potential methods that can achieve deep CO2 emission reduction in view of its advantages including low-cost CO2 sorbent11 and proven CFB technology.12 The CO2 capture capacity of the calcium-based sorbent can be further enhanced by synthesizing inert supported sorbent13,14 and template-assisted synthesis approach.15,16 Therefore, the cost of this technology can be further reduced. Our previous research has proposed lime mud as CO2 sorbent in calcium looping process.17 After prewash and prolonged carbonation treatment, the lime mud presented relatively higher CO2 capture capacity compared with limestone. Ma et al18 used lime mud as CaO precursor to synthesize highly reactive calcium-based sorbent. The carbonation conversion of the obtained calcium-based sorbent can be higher than 38% after 50 cycles. The carbonation time, that is the time duration of the carbonation stage, was chosen in the range of 10-40 minutes when testing the CO2 capture capacity of the sorbents. However, the lasting time that the sorbent can stay in the carbonator was only 1-5 minutes in calcium looping process.19 Therefore, the carbonation conversion that the sorbent can obtain during the initial fast chemical reaction controlled stage, usually lasts for 1-3 minutes, is relatively significant to judge the CO2 capture capacity of the sorbents. A surface reaction-controlled kinetic model with a Boltzmann equation, developed by Lan and Wu,20 was proven to be more appropriate than the core shrinking model and the random core model to describe the carbonation reaction between CO2 and CaO during the chemical reaction controlled stage. In this manuscript, the carbonation kinetics of the lime mud in the chemical reaction controlled stage was analyzed by this surface reaction-controlled kinetic model. The effects of prewash and prolonged carbonation treatment on the carbonation kinetics of the lime mud were also discussed in detail.

SUN ET AL.

FIGURE 1

2 2.1

XRD spectrum of lime mud and calcined lime mud

EXPERIMENTAL

Samples

The lime mud (LM) in this research was sampled from a paper mill located in Shandong province, China. The components of the LM, detected by XRD analysis, were CaCO3 and a small amount of Ca(OH)2, as shown in Figure 1. All the CaCO3 and Ca(OH)2 in LM decomposed to CaO after calcination. A kind of limestone was employed as contrast sample. The X-ray fluorescence (XRF) results of the LM and limestone are shown in Table 1. CaCO3 was doped with CaCl2 by wet impregnation method to check the effect of Cl on carbonation performance of the LM, with the Cl/Ca molar ratio differed from 0.25:100 to 2:100. The detailed modification process was presented elsewhere.17 In order to mitigate the adverse effect of Cl on the CO2 capture capacity, the LM was prewashed to decrease the content of Cl. The prewash process was presented as follows: 100 g LM and 400 mL distilled water were firstly mixed in a beaker at ordinary temperature. After stirring for 2 hours, the mixture was filtered to remove the liquid. Then, the solid residue and 200 mL distilled water were mixed and stirred for 2 hours. After filtration, the mixture was dried in the oven at 120°C. Then, the solid residue obtained was called prewashed lime mud (PLM). The particle sizes of all the sorbents were below 0.125 mm. A prolonged carbonation process was proposed to improve the microstructure and enhance the CO2 capture capacity of the calcined LM and PLM. The prolonged carbonation of the calcined sample was only performed in the 1st carbonation. Before used as CO2 sorbent, the calcined PLM was firstly carbonated in 100% CO2 for 3-12 hours at 700°C. Then, the PLM after prolonged carbonation treatment was sent for carbonation kinetics test in the dual-fixed bed reactor and the thermogravimetric analyzer.

SUN ET AL.

TABLE 1

Chemical components of LM, PLM, and limestone

Sample

CaO

MgO

SiO2

Al2O3

Fe2O3

SO3

Ti2O

K2O

Na2O

Others

LOI

52.39

0.7

2.52

1.49

0.29

0.31

0.056

0.013

0.14

0.88

0.049

41.16

PLM

52.52

0.73

2.64

1.71

0.27

0.3

0.066

0.013

0.044

0.30

0.051

41.36

Limestone

52.08

1.32

3.32

0.53

0.03

0.02

0.47

42.23

2.2 | Carbonation kinetics performance of the sorbent The cyclic calcination/carbonation tests of the LM, PLM, and limestone were accomplished in a dual-fixed bed reactor (DFR), as shown in Figure 2. The internal diameter of the DFR is 30 mm, and the constant temperature zone of the reactor is about 300 mm, which can make sure that the samples stay in the constant temperature zone at any operating mode. The N2 and CO2 feed were controlled by mass flow controllers and introduced into the reactor. The sample was firstly calcined for 10 minutes at 850°C in pure N2 and then was carbonated at 700°C for 20 minutes. The sample mass after calcination and carbonation was measured by a delicate electronic balance, and the carbonation conversions of the sorbents were calculated according the mass change during the carbonation and calcination stage, as shown in Equation (1).

m − mcal MCaO ⋅ XN = N m0 A MCO2

(1)

where XN is the carbonation conversion of the sample after N cycles. m0 is the initial mass of the sample. mN is the mass of the carbonated sample after N cycles. mcal is the mass of the completely calcined sample (the mass of the sample after each calcination is the same). MCaO and MCO2 are molar masses of the CaO and CO2, respectively. A is the content of CaO in the initial sample. A thermogravimetric analyzer (TGA) was employed to investigate the carbonation kinetics of the sorbent during multiple cycles. After multiple calcination/carbonation cycles, the sorbents were sampled from the DFR and sent for TGA

F I G U R E 2 Schematic diagram of dual-fixed-bed reactor (DFR)

analysis. The crucible containing 10 ± 0.1 mg sample was firstly put into the furnace of the TGA. The reaction temperature was increased to 850°C at a heating rate of 30°C/min, and then, the temperature was constant for 10 min in pure N2. The sample was completely calcined in this period. Then, the temperature decreased to 700°C at 30°C/min in pure N2. The gas mixture was switched to the carbonation atmosphere (15% CO2 balanced with N2) at the moment when the temperature reached 700°C, and the temperature was constant at 700°C for 30 minutes for carbonation reaction. One data were collected per 3 second during the carbonation process. The gas flow was 120 mL/min. The carbonation rate of the sample was calculated according to Equation (2).

rN =

dXN dt

(2)

where rN is carbonation rate of the sample at t (carbonation time) in the Nth carbonation, s−1. t denotes the reaction time, s.

2.3

Kinetics analysis model

A surface reaction-controlled kinetic model with a Boltzmann equation was employed to describe the reaction of CO2 and CaO during the chemical reaction-controlled stage, the curve of which is an S-type. The fitting equation is shown in Equation (3):

XN,t = Xu −

Xu [ t−t k ] ( ) 1 + exp X 0 u

(0 ≤ XN,t ≤ Xu )

(3)

SUN ET AL.

where Xu is the ultimate carbonation conversion in the chemical reaction controlled stage, mol/mol; k is the reaction rate constant in the chemical reaction controlled stage, s−1; t0 is the time at which the carbonation achieves highest carbonation rate, s. The carbonation rate rN,t is described in Equation (4)

rN,t =

dXN,t dt

=k×

XN,t Xu

( 1−

XN,t

)

(4)

d2 XN,t dt2

) dXN,t k ( Xu − 2XN,t 2 dt Xu

2.4

perform the differential calculation according to Equation (4), and Equation (5) is obtained:

drN,t

conversion at the point of maximum carbonation rate. Then, the carbonation process of the sorbent can be divided into chemical reaction controlled stage and diffusion controlled stage by the value of Xu. Here, this surface reaction-controlled kinetic model was employed to discuss the carbonation kinetics of the LM and PLM during the chemical reaction controlled stage.

(5)

when drN,t/dt = 0, it is related to the point of maximum carbonation rate. Here, XN,t is equal to half the value of Xu. According to this, the value of Xu can be obtained by 2 times of the

Microstructure analysis

The chemical components of the LM, PLM, and limestone were examined by X-ray fluorescence (XRF). The pore volume and pore area distributions of the calcined LM, PLM, and limestone after different cycles were examined by a nitrogen adsorption analyzer (Micromeritics, ASAP 2020-M). The pore volume and pore size distribution of the sample were computed by BJH (Barrett-Joyner-Halenda) model, the BET surface of the sample was calculated by BET model.

RESULTS AND DISCUSSIONS

3.1 | Carbonation kinetics of LM in multiple cycles

F I G U R E 3 Carbonation conversions of LM and limestone during multiple calcination/carbonation cycles (a)

Figure 3 shows the carbonation conversions of the LM and limestone in multiple calcination/ carbonation cycles. The LM exhibits more stable CO2 capture capacity with cycle number, while it shows lower carbonation conversions in the initial cycles compared with the limestone. The carbonation conversions of the LM were higher than those of the limestone after 15 cycles. However, this result was obtained in a dual-fixed bed reactor with a relatively long carbonation time. Figure 4A,B present the carbonation conversions and carbonation rates of the LM and limestone with carbonation (b)

t/s

F I G U R E 4 Carbonation conversions and rates of the LM and limestone with carbonation time during multiple cycles. A, Carbonation conversion and B, carbonation rate

SUN ET AL.

time in multiple cycles. It can be seen that the LM shows much slower carbonation rate during the initial fast reaction stage, while it presents higher carbonation rate during the following diffusion controlled stage compared with the limestone in the same cycle. The point of maximum carbonation rate in each carbonation process can be obtained from Figure 4B, according to which the Xu can be confirmed from Figure 4A. Then, the carbonation curves of the LM and limestone during the chemical reaction controlled stage were fitted by Equation (3), as shown in Figure 5. The correlation coefficients of all the curves are in the range of 0.980-0.998, which means it is feasible to use this surface reaction-controlled kinetic model to describe the carbonation of the LM and limestone during the chemical reaction controlled stage. The kinetic parameters obtained by this model are shown in Table 2. The parameter tcrcs in Table 2 denotes the time duration of the chemical reaction controlled stage of the sorbents. The values of k and tcrcs of the LM are much smaller compared with those of the limestone in the same cycle, as can be seen in Table 2. Taking the 1st cycle as an example, the values of k and tcrcs of the LM are only 62.6% and 31.3% those of the limestone, which means that the LM shows much slower carbonation rate and much shorter time duration in the chemical reaction controlled stage. Thus, the Xu that can be achieved in this stage for the LM, which is mainly determined by k and tcrcs, is much smaller than that for the limestone. We also can see from Table 2 that the values of Xu of the LM in different cycles are very small, with a value that no more than 0.03 after 15 cycles. Such a low CO2 capture capacity of the LM in the chemical reaction controlled stage makes it not suitable to be used as CO2 sorbent in calcium looping process. The main components of the LM and limestone are all CaCO3, and the corrected CaO contents that in the LM and limestone are almost the

F I G U R E 5 Fitting results of the carbonation conversions of LM and limestone during the chemical reaction controlled stage in multiple cycles

same, as shown in Table 1. Maybe, the complex impurities in the LM or the specific microstructure characteristics of the calcined LM were the reasons why the LM showed such low carbonation capacity during the chemical reaction controlled stage.

3.2 | Effect of Cl on the carbonation kinetics of calcium-based sorbent As shown in Table 1, the chemical components of the LM are much more complex compared with the limestone. Especially, the content of Cl in the LM is relatively high. The other impurities except Cl have been proved to be beneficial or not attributable to CO2 capture capacity of the calciumbased sorbents.21,22 The effect of Cl on CO2 capture capacity of the calcium-based sorbent was detected by doping CaCl2 into CaCO3 through wet impregnation method. The carbonation conversion and carbonation rate of Cl-doped CaCO3 with carbonation time during the first cycle are shown in Figure 6, and the fitting results of the carbonation process of Cl-doped CaCO3 with different Cl/Ca molar ratio during the chemical reaction controlled stage are shown in Figure 7. The obtained kinetic parameters were presented in Table 3. We can see from Figures 6 and 7 and Table 3 that addition of Cl has adverse effect on the CO2 capture performance of the calcium-based sorbent, especially the carbonation process during the chemical reaction controlled stage. The values of k and tcrcs of Cl-doped CaCO3 decrease dramatically with increasing the Cl/Ca molar ratio. It indicates that the Cl-doped CaCO3 shows much slower carbonation rate and shorter duration time during the chemical reaction controlled stage with increasing the additive amount of Cl in CaCO3. Therefore, smaller carbonation conversion in chemical reaction controlled stage is achieved. When the Cl/Ca molar ratio is larger than 2:100, the Xu that can be achieved is very low. It has been proven that doping the calcium-based sorbent with small amount of chloride can improve the long-term CO2 capture capacity, while larger doping leads to decrease in pore volume and gives marked reduction in capacity.23,24 The similar result was obtained here. As is shown in Table 3, the pore volume and BET surface area decreased dramatically with the molar ratio of Cl/Ca when the value was higher than 0.25:100. The pore volume and surface area of the calcined sorbent decreased by 71.3% and 44.5% respectively when the molar ratio of Cl/Ca in the sorbent was increased from 0 to 2:100. After Cl doping, the CO2 diffusion and carbonation reaction were limited during the carbonation process. The corresponding lower Xu, k, and tcrcs were achieved for Cl doped sorbent. The Cl/Ca molar ratio in the LM which can be calculated according to the XRF results shown in Table 1 is 2.6:100. Therefore, the relatively high content of Cl in the LM can be judged as one of the major reasons that lead to

SUN ET AL.

Sample

PLM

PLM after 9 h prolonged carbonation Limestone

to (s)

tcrcsa (s)

T A B L E 2 Carbonation kinetic parameters of the LM and limestone during the chemical reaction controlled stage

0.0127

0.090

.998

0.0040

0.032

.993

0.0033

0.031

.993

0.0027

0.026

.980

0.0165

0.238

132

.988

0.0084

0.100

.962

0.0079

0.097

.950

0.0066

0.095

.962

0.0250

0.361

102

.996

0.0169

0.140

.996

0.0203

0.634

102

192

.996

0.0146

0.421

177

.996

0.0080

0.216

153

.995

tcrcs denotes the time duration of the chemical reaction controlled stage.

F I G U R E 6 Effect of Cl content on CO2 capture capacity of calcium-based sorbent in the 1st cycle

TABLE 3

F I G U R E 7 Fitting results of the carbonation conversions of Cl-doped CaCO3 with different Cl/Ca molar ratio during the chemical reaction controlled stage in the first cycle

Carbonation kinetic parameters of Cl-doped CaCO3 during chemical reaction controlled stage during the 1st cycle

Sample

Cl/Ca molar ratio

t0 (s)

tcrcs(s)

Pore volume (cm3/g)

Surface area (m2/g)

CaCO3

0.0234

0.480

141

.993

0.08

12.01

CaCO3 + CaCl2

0.25:100

0.0231

0.448

111

.993

0.06

12.2

CaCO3 + CaCl2

0.50:100

0.0229

0.358

.993

CaCO3 + CaCl2

1:100

0.0220

0.314

.992

0.042

10.62

CaCO3 + CaCl2

2:100

0.0174

0.110

.997

0.023

6.67

CaCO3 + CaCl2

4:100

0.0174

0.108

.998

the poor CO2 capture performance of the LM in chemical reaction controlled stage. Figure 8 shows the pore volume distribution of the calcined LM, CaCO3, and Cl-doped CaCO3 with a Cl/Ca molar

ratio of 2:100 at the first cycle. The calcined LM and Cldoped CaCO3 with a Cl/Ca molar ratio of 2:100 show similar pore volume distribution characteristics, with less pores distributed in the range of 10-100 nm compared with calcined

SUN ET AL.

F I G U R E 8 Pore volume distribution of calcined LM, CaCO3, and Cl-doped CaCO3 with a Cl/Ca molar ratio of 2:100 at the first cycle

F I G U R E 9 Carbonation conversions and carbonation rates of the PLM with carbonation time during different cycles

CaCO3. It indicates that the Cl can aggravate the sintering of the LM during the calcination at high temperature, leading to reduction of pores distributed in 10-100 nm, which have been proved to be beneficial to diffusion of CO2 in the sorbent to react with CaO.25 Therefore, it is predictable that reducing the Cl content in the LM can enhance its CO2 capture capacity.

stage are shown in Figure 10, and the obtained kinetic parameters were presented in Table 2. As can be seen in Table 2, the PLM shows much better carbonation performance compared with the LM. The values of k and tcrcs of the PLM are all higher than those of the LM during the same cycle. For example, the values of k and tcrcs during the 1st cycle are respectively increased by 29.9% and 120% after prewash treatment. The values of k and tcrcs of the PLM in the 15th cycle are 144% and 28.0% higher than those of the LM in the same cycle. In other words, the PLM shows faster carbonation rate and longer duration time in the chemical reaction controlled stage in the same cycle. Certainly, higher carbonation conversion can be achieved for the PLM during the chemical reaction controlled stage. The Xu of the PLM in the 1st and 15th cycles is 2.64 and 3.65 times as those of the LM in the same cycle. If the LM cannot be reused effectively, the major disposal for LM is landfill. Simultaneously, the Cl in the LM will penetrate into the underground water and lead to serious pollution. Therefore, the Cl in the LM was hard to handle and should be heavily focused on. In this manuscript, the LM was proposed to be CO2 sorbent in calcium looping process. A prewash process was raised to decrease the Cl in the LM. Not only the CO2 capture capacity of the LM was enhanced after prewash process, the Cl in the LM was also transferred into the discharged water, in which the Cl can be removed in more convenient ways. Dechloridation equipment can be employed to remove most of the Cl in the discharged water. After that, the spent water can be sent to the nearby sewage treatment plant for fine treatment before discharged to the environment. In this research, 400 g deionized water was used for 100 g LM during the prewash process. When applied to the practice, the deionized water can be replaced by the surface freshwater or the collected rainwater. Also, intense agitation can also be employed to enhance the dissolution of the Cl into the water and decrease the needed water.

3.3 | Effect of prewash treatment on the carbonation kinetics of LM A prewash treatment process was proposed to decrease the Cl content in the LM. As shown in Table 1, the Cl content in the LM decreases dramatically after the prewash treatment process. The carbonation conversions and carbonation rates of the PLM with carbonation time during different cycles are shown in Figure 9. The fitting results of the carbonation process of the PLM during the chemical reaction controlled

F I G U R E 1 0 Fitting results of the carbonation conversions of the PLM during chemical reaction controlled stage in the 1st cycle

SUN ET AL.

3.4 | Effect of prolonged carbonation treatment on the carbonation kinetics of the PLM We can see from the above discussion that prewash treatment process dramatically enhances the CO2 capture capacity of the LM during the chemical reaction controlled stage. However, the CO2 capture capacity of the PLM is still lower than that of the limestone during the chemical reaction controlled stage. One of the major problems for the LM is that the pores of the calcined LM distributed in 10-100 nm were very less. Here, we proposed a prolonged carbonation process to improve the microstructure of the calcined PLM, in the hope of further enhancing the CO2 capture capacity of the PLM. The CO2 capture performance of the PLM after prolonged carbonation treatment is shown in Figure 11. As shown in Figure 11A, prolonged carbonation treatment successfully improves the carbonation conversion of the PLM in multiple cycles. The CO2 capture capacity of the PLM increases with increasing the prolonged carbonation time when the prolonged carbonation time is shorter than 9 hours. Further extending the prolonged carbonation time has little effect on the CO2 capture of the PLM when longer than 9 hours. It seems that 9 hours is the optimum prolonged carbonation time for the PLM. The carbonation conversion and carbonation rate of the PLM after 9 hours prolonged carbonation in different cycles is shown in Figure 11B. The fitting results of the carbonation process of the PLM after 9 hours prolonged carbonation treatment during the chemical reaction controlled stage are shown in Figure 12 and the obtained kinetic parameters were presented in Table 2. As is expected, prolonged carbonation treatment further enhances the carbonation performance of the PLM during the chemical reaction controlled stage. The values of k and tcrcs of the PLM are increased by 51.5% and 6.3% after prolonged (a)

carbonation treatment in the 1st cycle, and the value of Xu is finally increased by 51.7%. The value of Xu of the PLM after prolonged carbonation treatment is still higher than that of the PLM in the 15th cycle. It means that prolonged carbonation treatment further enhances the carbonation performance of the PLM during the chemical reaction controlled stage. Though still lower compared with that of the limestone, the CO2 capture capacity of the LM during the chemical reaction controlled stage is effectively enhanced by prewash treatment and subsequent prolonged carbonation treatment. The PLM after prolonged carbonation treatment shows higher carbonation rate but shorter duration time during the chemical reaction controlled stage compared with the limestone. The final values of Xu for the PLM after prolonged carbonation treatment are approximate to those of the limestone during multiple cycles, which means that the LM can be effectively utilized as an alternative of the limestone to capture CO2 in calcium looping process after prewash and following prolonged carbonation treatment process. Table 4 showed the pore distribution parameters of the limestone, LM, PLM before and after prolonged carbonation treatment in the 1st calcination. Figure 13A,B showed the pore volume distributions and cumulative pore volumes of the calcined limestone, LM, PLM before and after prolonged carbonation treatment in the 1st cycle. The BET surface area of the calcined LM is even larger than that of the calcined limestone, which means that the calcined LM can afford more places for the carbonation reaction. It seems that the LM should present higher carbonation conversion compared with limestone. However, the pore volume distributes in 1-100 nm (V1-100nm) of the calcined LM is less than that of the calcined limestone. Furthermore, the pore volume of calcined LM is mainly distributed in the range of 1-10 nm, as shown in Figure 13B.The value of V10-100nm of the calcined LM, which has been proved to be significant for the (b)

F I G U R E 1 1 The CO2 capture performance of the PLM after prolonged carbonation treatment during multiple cycles. A, XN with cycle number and B, XN and rN with carbonation time

SUN ET AL.

in 1-10Â nm, it is easily to be blocked during carbonation process of the sorbent, because of which much of the surface is coated in the product layer and cannot be effectively utilized for carbonation reaction. Therefore, the LM shows much poorer carbonation performance compared with the limestone during the chemical reaction controlled stage. The prewash treatment obviously improves the microstructure of the LM. The surface area and V1-100 nm of the calcined PLM are increased by 74% and 56% compared with those of the calcined LM. Especially, the value of V10-100 nm of the calcined PLM is 4.5 times that of the calcined LM. The prolonged carbonation treatment further enhances the microstructure of the calcined PLM. Though the surface area is decreased, the value of V10-100 nm for the PLM is increased by 3.4 times through prolonged carbonation process. The microstructure of the PLM after prolonged carbonation process is much more beneficial to CO2 capture compared with the LM, with

F I G U R E 1 2 Fitting results of the carbonation conversions of the PLM after prolonged carbonation treatment during chemical reaction controlled stage T A B L E 4 Effect of prewash and prolonged carbonation treatment on pore distribution parameters of the calcined sorbents

Sample

Cycle

Surface area (m2/g)

V1-100 nm (cm3/g)

V1-10 nm (cm3/g)

V10-100 nm (cm3/g)

6.2

0.016

0.014

0.002

P LM

10.8

0.025

0.016

0.009

PLM after prolonged carbonation

5.6

0.051

0.011

0.040

Limestone

4.25

0.047

0.002

0.045

(a)

(b)

F I G U R E 1 3 Pore volume distributions of the calcined limestone, LM, PLM before and after prolonged carbonation treatment in the 1st cycle. A, Pore volume distribution and B, cumulative pore volume

CO2 capture of calcium-based sorbent,26 is only 4.4% that of the calcined limestone. The diffusion resistance of CO2 in the calcined LM is larger than that in the calcined limestone. Since most of the pores of the calcined LM distributes

smaller diffusion resistance of CO2 in the sorbent and higher utilization efficiency of the surface area. As is shown in TableÂ 4, the values of surface area for the calcined PLM after prolonged carbonation treatment is a

SUN ET AL.

little larger compared with that for the calcined limestone, which means that the calcined PLM after prolonged carbonation treatment can afford much more surface for the carbonation reaction. Thus, the value of k for PLM after prolonged carbonation treatment is larger than that of limestone. We can see from Figure 13A that the pores distributed in 10-30 nm for the calcined PLM after prolonged carbonation treatment are more than the calcined limestone, while the pores in 30100 nm are fewer. Thus, the average pore diameter for the calcined PLM after prolonged carbonation treatment is smaller, which means that the pores of the calcined PLM after prolonged carbonation treatment are more easily to be blocked. Therefore, the t0 for the calcined PLM after prolonged carbonation treatment is shorter than that for the limestone.

CONC LUSI ONS

Lime mud, a kind of industrial waste produced in paper mill, was proposed as CO2 sorbent in calcium looping process in this research. The higher content of Cl in the LM leads to more serious sintering of the sorbent when calcined at high temperature. Therefore, the LM shows relatively lower CO2 capture capacity compared with the limestone during the chemical reaction controlled stage. A prewash treatment process was proposed to decrease the Cl content in the LM and enhance the CO2 capture capacity of the LM. The values of surface area and pore volume in 10-100 nm of the PLM are higher than those of the LM, which makes it easier for the diffusion of CO2 in the sorbent to react with CaO. Therefore, the PLM shows faster carbonation rate and carbonation conversion in chemical reaction controlled stage compared with the LM. A prolonged carbonation treatment was proposed to further improve the microstructure of the PLM. Though the value of the surface area is decreased, the pore volume distributed in 10-100 nm for the PLM after prolonged carbonation treatment is increased, leading to less CO2 diffusion resistance and more efficient utilization of the surface area in the sorbent. After prewash treatment and the following prolonged carbonation treatment, the LM shows similar carbonation performance compared with the limestone. It seems that the LM after prewash treatment and subsequent prolonged carbonation treatment can be effectively used as CO2 sorbent in calcium looping process. ACK NOW L E D G M E N T Financial supports from National Natural Science Foundation of China (51706094, 51661145011) are sincerely acknowledged. ORCI D Rongyue Sun

https://orcid.org/0000-0002-9984-5016

R E F E R E NC E S 1. Correa THA, Toledo R, Silva NS, Holanda JNF. Novel nano-sized biphasic calcium phosphate bioceramics (β-CPP/β-TCP) derived of lime mud waste. Mater Lett. 2019;243:17-20. 2. Said AEAA, Aly AAM, Ahmed HS. Development and utilization of lime-mud waste as filler for production of green paper. Environ Prog Sustain. 2019;38:e13022. 3. Zhang J, Zheng P, Wang Q. Lime mud from papermaking process as a potential ameliorant for pollutants at ambient conditions: a review. J Clean Prod. 2015;103:828-836. 4. Qin J, Cui C, Cui X, Hussain A, Yang C, Yang S. Recycling of lime mud and fly ash for fabrication of anorthite ceramic at low sintering temperature. Ceram Int. 2015;41:5648-5655. 5. Madrid M, Orbe A, Carré H, García Y. Thermal performance of sawdust and lime-mud concrete masonry units. Constr Build Mater. 2018;169:113-123. 6. Li H, Niu S, Lu C, Liu M, Huo M. Transesterification catalyzed by industrial waste-Lime mud doped with potassium fluoride and the kinetic calculation. Energ Convers Manage. 2014;86:1110-1117. 7. Chen Y, Huang B, Huang M, Lu Q, Huang B. Sticky rice lime mortar-inspired in situ sustainable design of novel calcium-rich activated carbon monoliths for efficient SO2 capture. J Clean Prod. 2018;183:449-457. 8. Fashi F, Ghaemi A, Moradi P. Piperazine-modified activated alumina as a novel promising candidate for CO2 capture: experimental and modeling. Greenhouse Gas Sci Technol. 2019;9:37-51. 9. Zhao N, Xu T, Wang K, Tian H, Wang F. Experimental study of physical-chemical properties modification of coal after CO2 sequestration in deep unmineable coal seams. Greenhouse Gas Sci Technol. 2018;8:510-528. 10. Xu Y, Jin B, Zhao Y, Hu EJ, Chen X, Li X. Numerical simulation of aqueous ammonia-based CO2 absorption in a sprayer tower: an integrated model combining gas-liquid hydrodynamics and chemistry. Appl Energ. 2018;211:318-333. 11. He D, Qin C, Manovic V, Ran J, Feng B. Study on the interaction between CaO-based sorbents and coal ash in calcium looping process. Fuel Process Technol. 2017;156:339-347. 12. Zhou L, Duan L, Anthony EJ. A calcium looping process for simultaneous CO2 capture and peak shaving in a coal-fired power plant. Appl Energ. 2019;235:480-486. 13. Benitez-Guerrero M, Valverde JM, Perejon A, Sanchez-Jimenez PE, Perez-Maqueda LA. Calcium-Looping performance of mechanically modified Al2O3-CaO composites for energy storage and CO2 capture. Chem Eng J. 2018;346:549-556. 14. Zhang Y, Gong X, Chen X, Yin L, Zhang J, Liu W. Performance of synthetic CaO-based sorbent pellets for CO2 capture and kinetic analysis. Fuel. 2018;232:205-214. 15. Sun J, Liang C, Tong X, et al. Evaluation of high-temperature CO2 capture performance of cellulose-templated CaO-based pellets. Fuel. 2019;239:1046-1054. 16. Chen J, Duan L, Sun Z. Accurate control of cage-like CaO hollow microspheres for enhanced CO2 capture in calcium looping via a template-assisted synthesis approach. Environ Sci Technol. 2019;53:2249-2259. 17. Sun R, Li Y, Liu C, Xie X, Lu C. Utilization of lime mud from paper mill as CO2 sorbent in calcium looping process. Chem Eng J. 2013;221:124-132.

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18. Ma A, Jia Q, Su H, et al. Study of CO2 cyclic absorption stability of CaO-based sorbents derived from lime mud purified by sucrose method. Environ Sci Pollut Res. 2016;23:2530-2536. 19. Duelli G, Bidwe AR, Papandreou I, Dieter H, Scheffknecht G. Characterization of the oxy-fired regenerator at a 10 kWth dual fluidized bed calcium looping facility. Appl Therm Eng. 2015;74:54-60. 20. Lan P, Wu S. Synthesis of a porous Nano-CaO/MgO-based CO2 adsorbent. Chem Eng Technol. 2014;37:580-586. 21. Ma X, Li Y, Zhang W, Wang Z, Zhao J. DFT study of CO2 adsorption across a CaO/Ca12Al14O33 sorbent in the presence of H2O under calcium looping conditions. Chem Eng J. 2019;370:10-18. 22. Pi S, Zhang Z, He D, Qin C, Ran J. Investigation of Y2O3/MgOmodified extrusion- spheronized CaO-based pellets for high-temperature CO2 capture. Asia-Pac J Chem Eng. 2019;14(6):e2366. https://doi.org/10.1002/apj.2366 23. Al-Jeboori MJ, Fennell PS, Nguyen M, Feng K. Effects of different dopants and doping procedures on the reactivity of CaO-based sorbents for CO2 capture. Energ Fuel. 2012;26:6584-6594.

24. Xu Y, Ding H, Luo C, et al. Potential synergy of chlorine and potassium and sodium elements in carbonation enhancement of CaObased sorbents. ACS Sustain Chem Eng. 2018;6:11677-11684. 25. Lu A, Lin Q, Wu S. Synergy of pore size and specific surface area on the CO2 sorption performance of nano CaO-based sorbents. J Nanosci Nanotechno. 2019;19:3205-3209. 26. Ma X, Li Y, Yan X, Zhang W, Zhao J, Wang Z. Preparation of a morph-genetic CaO-based sorbent using paper fibre as a biotemplate for enhanced CO2 capture. Chem Eng J. 2019;361:235-244.

How to cite this article: Sun R, Xiao R, Ye J. Kinetic analysis about the CO2 capture capacity of lime mud from paper mill in calcium looping process. Energy Sci Eng. 2020;00:1â€“11. https://doi.org/10.1002/ ese3.792

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HOW TO TRANSPORT BULKY ITEMS – WITHOUT BREAKING THE LAW Drivers have been advised on the safe and legal practices to adhere to when transporting bulky items that might have to stick out or be fixed on top of vehicles. Motoring experts from LeaseVan.co.uk have warned drivers about the rules of overloading their cars and vans. When travelling with items sticking outside of a vehicle, one of the most important things to consider is that lights and number plates are still visible. Loads must also be carefully secured and marked if necessary. Tim Alcock from LeaseVan.co.uk said: “It’s not uncommon to see cars packed with items of furniture, bikes, or even Christmas trees throughout the festive period, but drivers should be very careful and prepare properly if their vehicle is to be loaded in such a way. If loads exceed certain lengths or widths, you might have to give advance notice to the police, including details like the time, date, and route of your proposed journey. At the very least, you may just have to mark the end of a load sticking out of your vehicle with something like a red cloth, or a high vis jacket, strap or material. Some scenarios might also require you to drive with an ‘attendant’ who can give warning of any danger likely to be caused by the vehicle on the journey. Vehicles that are overloaded can pose dangers to the driver, passenger, and other road users, and if a vehicles’ gross or axle weight limits are exceeded, the driver risks prosecution.” 1. Loads overhanging the front or rear of a vehicle For objects that stick out no more than one metre either to the front or back of a vehicle, there are no specific requirements. If the load projects between 1-2 metres at the back, the end must be made clearly visible and marked with something bright like a red cloth or a high vis jacket, strap, or material. For projections more than 2 metres, but not exceeding 3.05 metres towards the front or back, you’ll need to use special Overhanging Load markers and have an attendant for loads projecting forwards. For anything exceeding 3.05 metres, you need to give two clear working days’ notice to the local police, have an attendant, and use Overhanging Load markers. 2. Loads overhanging the side of the vehicle If the load projection or overall width is between 305mm and 3.5 metres, you’ll need to give two clear working days’ notice to pole, use marker boards to the front and rear, and additional lights may be required during hours of darkness or poor visibility. If the width is more than 3.5 metres, you’ll need to do the same thing, but an attendant will also be required. Loads are not permitted to exceed 4.3 metres overall width. 3. On the roof Roof racks and boxes are perfect for carrying large or awkward items, but you need to make sure you stay within the maximum permitted roof load for your vehicle. Check your vehicle’s manual for details. You should also make sure anything attached to the roof is fitted and secured properly. Ropes and straps can become loose over time, so stop regularly to check them. Don’t forget the extra height roof racks and bulky items can add too.

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FOURTEEN PRACTICAL ITEMS TO KEEP IN YOUR CAR AT ALL TIMES New drivers have been advised on the essential items that should be kept in vehicles at all times, from reflective triangles and jump leads to first aid kits and maps. Motoring experts from LeaseCar.uk have revealed 14 practical items drivers should keep in their cars and vans to avoid getting caught out in bad weather or when broken down. Some of the most common causes of breakdowns include tyre punctures, flat batteries and empty fuel tanks, so drivers should keep spare tyres, jump leads and empty fuel cans to help in these situations. But even everyday items like blankets and sunglasses are worth having to hand to make journeys safe and comfortable. A spokesperson for LeaseCar.uk said: “Whether you’re heading out on a big road trip or simply commuting to and from work, it’s a good idea to have all the necessary essentials for comfort, safety, and those dreaded breakdowns. Packing light has its advantages, but keeping these items in your car at all times could be a big help if the needs arise.” 1. Reflective triangles and a high visibility jacket: If you’re unfortunate enough to break down, you’ll need to use reflective triangles in order to alert other road users. Wearing a high-vis jacket will also ensure that you’re seen by other road users – this is especially vital if you have to walk to find an emergency telephone on the hard shoulder, or if you break down in the dark. 2. Spare tyre and car jack: Probably one of the most common causes of breakdowns are tyre punctures, so it’s always a good idea to keep a spare tyre with you. Most new cars come with one, but if yours doesn’t have one, it’s definitely worth making the investment. You should also pack a car jack and wrench, otherwise you won’t be able to change it if needed. 3. Jump leads: Another common reason for breakdowns is a flat battery – particularly in the colder weather when car batteries tend to be more temperamental. If you buy a set of jump leads, you will be able to get a jump start from another driver and be back on the road in no time. 4. Mobile phone car charger: If you break down, there’s no telling how long you might be stuck waiting for recovery or traffic to clear up. The last thing you need is a dead battery when you need to call a recovery service, so always keep a portable phone charger in your car. 5. Spare coolant, oil and windshield-washer fluid: Checking these regularly can help you avoid getting caught out, but it’s always good to have extras to hand, just in case. 6. Wind-up torch: If you have to check under the hood of your car in the dark, you’ll struggle without a torch. 7. Empty fuel can: Keep an empty fuel can in your car so that if you run out of fuel on the road, you’ll be able to walk or get a lift to the nearest petrol station to fill it up. 8. Non-perishable snacks: Energy or cereal bars are great to keep in your glove compartment just in case you need to keep your energy levels up. 9. First-aid kit: It’s a good idea to keep a simple first aid kit in the car in case of emergencies. You can buy these in some supermarkets, car stores, or online. 10. Sunglasses: When the sun is low in the sky, particularly around spring and autumn, the glare can be blinding so keep some sunglasses to hand. 11. Map: An old-fashioned paper road atlas can help you out in case you get lost and your phone is out of battery, data, or signal, and there aren’t any locals around to ask. 12. Change: Prevent getting caught out with unforeseen tolls or parking fees by keeping some change in the car. 13. Ice scraper: You’ll need this to clear your windscreen and windows in winter. 14. Blanket: If you’re caught out by unexpected rain and end up getting soaked, a spare blanket or towel is great for drying off or covering your car seat. It’s also great for impromptu picnics.

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Article 10 – Driving Issues

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

FIVE DIFFERENCES BETWEEN DRIVING VANS AND CARS As drivers begin to take to their vans again they’ve been warned of some of the differences between driving cars and vans which they may have forgotten. Experts from LeaseVan.co.uk are hoping that reminding drivers about the difference in speed limit and safety mirrors might stop van drivers from being fined or given points whilst out on the road. The top speed of vans should be 10mph less than cars when travelling on single or dual carriageways and motorways otherwise penalty points or fines could be handed out. Ensuring drivers are used to the width and turning circles of the vehicle will also help ensure any potential accidents are avoided. A spokesperson from LeaseVan.co.uk said: “It’s very easy when you’re used to driving a car to just jump into a van and think that everything is the same. However, this isn’t the case. The rules of the road are slightly different when in a van due to safety measures and the way the vehicle is built. Make sure you brush up on you van driving knowledge before you take to the road to help avoid any expensive fines or points.” These are LeaseVan.co.uk ’s reminders for van drivers: 1. Speed limit The speed limit is the same for both cars and vans when driving around residential areas. However, when vans get to single or dual carriageways and motorways, their speed limit is 10 miles per hour lower than that of cars. For single carriageways vans should be travelling at no faster than 50mph, and no faster than 60mph when on dual carriageways or motorways. 2. Rear view mirror Vans aren’t fitted with a rear-view window or mirror, making it even more important to check wing mirrors when undertaking manoeuvres such as reversing. Wing mirrors are often fitted with two mirrors, one with the same function as a cars wing mirror and another to act as a rear-view mirror. 3. Bridge and barriers Vans are often wider than cars, meaning that more care needs to be taken when it comes to signs stating the width of a barrier or tunnel, or the maximum load a bridge can take. The dimensions of your van should be easy to find in the vehicle’s manual. 4. Turning circle Vans have a much larger turning circle than that of cars, so make sure you leave more space when attempting manoeuvres such as a three-point turns. Even turning a corner could need you to take a longer line. If you’re getting used to your van, take it to a quiet area such as a big supermarket car park at night to get used to the van. 5. Loading If you plan on carrying lots of tools in the back of your van, or transporting big heavy objects, ensure it’s loaded correctly. Vans are at higher risk of becoming destabilised than cars, so ensure that heavier items are at the bottom of the vehicle. They should also be tied down so that if there is any movement internal damage won’t occur.

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Article 10 – Driving Issues

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

SIX POTENTIAL OUTCOMES OF BEING PULLED OVER BY THE POLICE Motorists have been warned about the potential consequences of driving illegally on the road and being pulled over. Motoring experts from LeaseVan.co.uk have revealed exactly what could happen if drivers are caught breaking the law. Motorists could be given a simple warning if they have been seen driving dangerously, however it could also result in vehicles being seized depending on the severity of the crime. By ensuring that vehicles are safe and legal and that drivers are below the drink-drive limit and are driving safely, they should avoid being pulled over. A spokesperson from LeaseVan.co.uk said: “Britain’s roads are patrolled by police to ensure they’re kept safe and that all road-users are abiding by the law. If they do spot illegal activity, they can ask motorists to pull over and conduct a series of checks. The outcome of these checks is dependent on the severity of the crime.” 1. Pull over If you see a police car pulling up behind you and indicating, make sure you pull over when it’s safe to do so. If the police car comes in front of you, follow them to the safe zone, otherwise pull over at a refuge space, never on the hard shoulder. As Rule 107 of the highway code states, it is an offence not to comply with directions. 2. Licenses The police can then ask to see your driving licence, insurance certificate and/or MOT certificate. If you don’t have these in the vehicle with you, you have seven days to take them to a police station. You’re breaking the law if you take any longer than the week given to hand them over. 3. Fixed Penalty Notices If the reason you’ve been pulled over is due to a minor motoring offence, the police could hand you a FPN (Fixed Penalty Notice). This could be for careless or inconsiderate driving, using a mobile phone, not wearing a seat belt or being too close to another vehicle. You could be fined up to £200 and get points on your license for any of these offences. They could also, however, just issue a warning. 4. Breath test It’s perfectly legal for a member of the police to pull over any vehicle at any time to breathalyse the driver if they think you’ve been drinking, you’ve committed a traffic offence and/or you’ve been involved in a road traffic accident. If you refuse to take this without giving a ‘reasonable excuse’ then you may be arrested. If you pass the test then you will be able to go on your way, however if the test is failed and you have too much alcohol in your system, you will be taken to a police station. 5. Vehicle faults If your vehicle is faulty, for example one of the brake lights is broken, the police can hand you a ‘vehicle defect rectification notice’. You have 14 days to get your vehicle fixed and provide proof that this has happened. 6. Seize your vehicle If the vehicle is being used for careless or inconsiderate driving, it could be seized. It could also be seized if it’s being driven by someone without a proper license or insurance, is dangerously, illegally or obstructively parked, or if it’s been abandoned. There is a £200 release fee to be paid in order to get the vehicle back, plus £20 for every day it’s been stored.

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

SIX HYGIENE TIPS TO KEEP DRIVERS SAFE UK motorists have been offered guidance to reduce the risk of contracting or spreading COVID-19 and maintain good hygiene levels when driving cars and vans. Motoring experts from LeaseVan.co.uk have released six pieces of important advice to help drivers maintain good health and personal hygiene while in their vehicles. If Brits are using vehicles to do essential outings, such as travel to work, picking up shopping, or attending medical appointments then they should stay alert to the dangers. From keeping hand sanitiser in the glovebox, to wiping surfaces regularly, there are certain steps vehicle owners should take to minimise the spread of germs. LeaseVan.co.uk guidance could help Brits who spend a lot of time behind the wheel steer clear of any virus or health condition that could harm their health. Tim Alcock from LeaseVan.co.uk said: “Many people are keeping each other safe and not using cars too much during the current pandemic. But COVID-19 has given us a newfound focus on hygiene, and rightly so. If British people can get into the routine of regular vehicle cleaning and sanitising, then they are giving themselves the best chance of protection from the virus. Sensible vehicle hygiene offers many benefits in regular life, as it can help avoid catching a cold or worse. So, we’ve put together a series of six top tips to help motorists steer clear of possible illness.” 1. Keep hand sanitiser in the vehicle Keep an alcohol-based antibacterial hand sanitiser gel in the glove box of your vehicle. This allows you to maintain proper hand hygiene and clean any bacteria from your hands before they touch anything. 2. Wipe surfaces regularly To stop bacteria building up, surfaces including the steering wheel, gear stick, door handles and dashboard should be wiped clean frequently. Seeing as these are major ‘touch points’, they should be cleaned often, especially if the vehicle is shared between multiple drivers. 3. Wear gloves when filling up Most petrol stations provide free disposable gloves. We advise drivers to take advantage of these to prevent any grime or bacteria touching their hands when refuelling their vehicles. 4. Allow fresh air in Breathing in too much recycled air from air-conditioning doesn’t help your respiratory system, so drivers on long journeys should wind their windows down occasionally to allow fresh air to circulate through the vehicle. 5. Try to minimise travel with unwell people The confined environment of a car or van can be a prime location for catching illnesses and viruses off friends and family. So, drivers should try to steer clear of offering lifts to anyone they know is under the weather, and even more so in current circumstances. 6. Catch coughs and sneezes, but not in your hands Drivers should cough and sneeze into a disposable tissue, their inner elbow or inside the collar of their shirt, rather than into their hands or completely unprotected – both of which can spread harmful bacteria. It’s never recommended to take a hand off the steering wheel for longer than necessary or if road conditions mean doing so could be dangerous though.

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

FOUR REASONS BEHIND THE UK AND EUROPEAN ROAD DIFFERENCES It’s been revealed that Ford’s The Model T car may be the reason that British and European drivers follow different road rules. Experts from car hire company StressFreeCarRental.com have researched and revealed the reasons behind the difference in British and European road rules. Widely recognised as the first car, The Model T was designed to be driven on the right-hand side of the road, meaning countries without road rules or a large road system made their roads fit the car. However, in Britain, cities had been designed to accommodate left hand turning meaning it would be difficult to switch sides. A spokesperson for StressFreeCarRental.com said: “There are many differences between our road rules and those we need to follow when in Europe, but often these differences aren’t questioned. It can seem like as long as there have been roads we’ve been driving on the left and Europeans on the right, but there must have been a reason for this. We have our ancestors to thank for some of the differences, but also the difference in culture and governing." 1. Side of the road The main difference when driving in Europe is that you drive on the right side of the road, as opposed to the left side of the road when in Britain. There are many schools of thinking about why this may be, but it’s thought we drive on the left due to London being designed to accommodate left-hand driving. Europeans may have been influenced by what many consider to be the first car, The Model T, which was designed with the driver on the left meaning it should be driven on the right-hand side of the road. 2. Driver's position Where the driver is sitting changes due to the side of the road which is driven. Front passengers should always be on the side closest to the pavement when the car is moving meaning passengers in both the front and back can exit onto the curb – as was done on the Model T. It can be assumed that in the interest of safety the same rules still apply now. 3. Speed Speed is measured in miles per hour (mph) when in Britain and this changes to kilometres per hour (km/h) when in Europe. It seems that it’s a hangover here in Britain from when we went from imperial to metric units – we’re the only country in Europe to measure speed by mph! 4. Motorways Whereas in the UK the fast lanes are the inner lanes on the right and you also overtake to the right, the is reversed in Europe. The fast lanes are those on the left, meaning you need to check your mirrors and indicate left when you want to overtake. This is not the only difference, with German autobahns famously having no speed limit. This has been put down to a gentlemen’s agreement between the German government and car producers. If the producers limited their cars to 250km/h the speed limit would be removed.

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A Guide to Phone Etiquette: Definition, Tips and Impact Communicating over the phone remains an important tool for businesses. Despite digital customer service communication advancements including email, texting and automated answering services, customers continue to use the telephone as their initial point of contact. Phone calls are often the first positive impression a client or customer will have of your business. This article will discuss tips to improve the quality of your phone calls and why phone etiquette is important. What is phone etiquette? Phone etiquette is the way you use manners to represent yourself and your business to customers via telephone communication. This includes the way you greet a customer, your body language, tone of voice, word choice, listening skills and how you close a call. Why is phone etiquette important? Identifying the tools to achieve proper phone etiquette can help your business to: x

Show professionalism: Whether you are a start-up or a well-established business, you and your representatives know your business best. Communicating your working knowledge to your callers using telephone manners should establish you as professionals worthy of repeat business dealings.

Create a good first impression. Everyone deserves to be treated with respect, and the initial phone call is your businesses’ chance to show the customer how pleasant it is to do business with you.

Increase customer trust and loyalty. If your business has face-to-face interactions with prospects who were initially just callers, the trust between you and your potential customer may grow, leading to them purchasing your goods or services more frequently.

Achieve high customer satisfaction ratings. When you meet customers’ needs over the phone, they can accurately assume that you will continue to meet their needs in person, creating a wellrounded and consistent experience.

Elements of proper phone etiquette To achieve excellent phone etiquette, you’ll need to apply the following items: x x x x x x

Friendly greetings Body language Tone of voice Tact Active listening Appropriate closing

Friendly greetings Answering an office phone properly requires a positive and cheerful disposition. Allow the positivity to resonate in your voice, offer a salutation, thank the customer for calling, introduce yourself and your business by name and then extend your help. This gives the customer a sense that you are warm, alert and pleased to help them with their inquiries. People often mimic positivity and will probably respond to your voice with the same enthusiasm you project.

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Article 11 – Phone Etiquette

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

Body language Body language plays a major role in communication, both in-person and on the telephone. When you speak on the phone, your body language still communicates how you are feeling. For example, when you smile and sit up straight, your voice is likely lighter and easily translated by the client as cheerfulness. Body language, facial expressions and gestures should remain professional while speaking on the telephone. Tone of voice Adopt a confident tone of voice to limit interruptions and maintain a professional engagement. You want the caller to know you are taking the time to understand their questions, while also delivering prompt service. The tone of your voice is an important factor in proper phone call manners since a caller may form an opinion of your business based on your attitude over the phone. Tact Unfortunately, there will be times when you must deliver potentially upsetting information to a customer over the phone. Remaining calm, while considering your word choice is the key to delivering messages tactfully to your caller. Your aim should be to communicate sensitive information truthfully, without offending your customer. If you don’t have an answer for them, be sure to offer them additional resources. Active listening To achieve excellent phone etiquette, it is necessary to develop active listening skills. Give the customer your undivided attention by minimizing distractions. Taking notes and repeating requests back to the caller lets them know that you care and are listening to only their needs at that moment. Active listening will likely help you respond to a customer’s requests appropriately. Appropriate closing Remember that closing a call can be just as important as the way you begin one. Before saying goodbye to your customer, thank them again and ask if you can assist them with anything else. Closing the call this way assures your caller that your business provides thorough customer service. Develop the habit of allowing the customer to hang up first to minimize accidental hang-ups. Tips to improve the quality of your phone calls Here are 10 action steps for you to consider: x

Answer the call within the first two or three rings. Providing a quick answer to customers’ phone calls should let them know that their business is important to you. When customers feel valued, they could be more likely to use your business. If you cannot answer the phone because you have clients in front of you, check the voicemail box and call back as soon as you are able.

Identify yourself and your business at the beginning of all calls. Identifying yourself and your business at the beginning of a call lets the customer know that they called the correct place. When you identify yourself, it is likely that the customer will feel more comfortable sharing the reason for their call and they’ll know who to ask for next time they call.

Let positivity resonate in your voice. Offering a positive tone of voice builds rapport, as the receiver becomes more open to sharing details about how you can best assist them with their needs. If possible, practice by recording your phone calls. Listen to the call recording, notice your tone and make corrections as necessary.

Watch your body language. When you hear the phone ring, it may be beneficial to immediately sit up straight and smile before answering. Your voice will likely sound more friendly and light to the customer if you practice changing your body language.

Minimize interruptions. Minimizing interruptions is possible, even in offices with ample foot traffic. Take a moment before answering a call to put aside items you were working on and prepare to give your full attention to your caller. For instance, try turning your back away from your crowded office when you answer phone calls, this way other individuals in the room will know you are unavailable to assist them while you are on the telephone.

Actively listen and take notes. When listening actively, it can be beneficial to give periodic affirmations that you understand the customer. For instance, you could say “I understand that you would like to return your product” or “Thank you for sharing your concerns.” Keeping a record of the Page 2 of 3

Article 11 – Phone Etiquette

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

conversation by taking notes can ensure that you remember and respond to all the customer’s concerns effectively. x

Be honest. Honesty is more important than trying to make your customer happy. If there’s something you know you can’t do for them, make them aware that you cannot perform the task they are requesting. Deliver the honest message in a polite and sympathetic way and your customer may still have a positive experience with your business after the call is over, even though you could not meet all of their needs. For instance, you could say “I understand your concerns, but unfortunately we cannot approve your request.” If you know of additional resources that the caller can use to meet their needs, provide them before closing the call.

Ask the caller before placing them on hold. You may need to place a caller on hold to get more information for them. For instance, you could say “Would you mind if I placed you on a brief hold to better assist you?” Asking the caller before placing them on hold allows them to know you are working on assisting them to the best of your ability and it displays professional courtesy.

Minimize emotional reactions. Keep your tone of voice positive. Find a break in the conversation and ask the caller politely if you may place them on hold. While they are on hold, take two deep breaths and remember to be objective and empathetic when faced with a challenging caller.

Make sure the callers’ needs are met before closing the call. Making sure you meet the customer’s needs is usually your goal when answering a phone call. The customer may often forget about other questions they have during the conversation. Asking if their needs are met or if they have questions is a great opportunity to be proactive and provide further clarification.

https://www.indeed.com/career-advice/career-development/phone-etiquette

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Working Remote? Biggest Dos and Conferencing

These Don'ts

Are the of Video

Here are 10 do’s and don’ts that I believe elevate the overall experience of a video conference. Do: Mute your microphone whenever you’re not speaking -- even if you’re alone in the room. Background noise can be an annoying distraction and stifle any meeting’s flow. Do: Be aware of your video settings. Check if your microphone is muted before delivering a two-minute monologue that no one will hear. Don’t: Position your camera too low, too high or hooked onto a different monitor. Weird camera angles can be very distracting -- and unflattering -- during video conference calls. Make sure your camera is eye level and on the monitor you plan to use for the conference. Do: Make sure your room is well lit (side lighting is the best). Few things are worse than having a professional meeting while feeling like you're talking to someone in a dungeon. Use natural light from windows or simply turn on the overhead light in the room to brighten up the conference. Do: Wear appropriate clothing. I know it can be tempting — especially if you work from home — to wear a work shirt and athletic shorts but dress as if you're meeting face to face. You never know if you're going to have to get up suddenly or if your camera might fall. So wear clean, professional clothing for your video calls. Do: Your wall art or decorations should be work-appropriate and your surroundings clean. If your room looks like a college dorm room after a bender, clean it or find a different room. This also includes your desk! Avoid having multiple coffee mugs, dishes and trash on the surface. Do: Test your microphone before you video call, especially if it's an important meeting. Test it by video conferencing your colleague before the meeting. Nothing is worse than trying to share something critical, and not being able to communicate clearly because your audio clarity and volume are poor. Do: If you're in a group call without video, introduce yourself before you talk. Consider something like "Hi it’s Jim, I have a question.” While several programs will notify you as to who is talking, conference line numbers will not. Therefore, be polite and introduce yourself. Don’t: Check or read emails or peruse articles while on the video call. This also includes doing additional work beyond the call. It’s easy for other participant’s to tell if you aren't fully focused and present during the video call. Do: When you're talking, look into the camera instead of looking at yourself talking on the computer screen. It will help others on the call feel like you're 100 percent engaged and present. It’s important to remember that video conferences are essentially in-person interactions that allow businesses to communicate more effectively. by Bryan Lovgren, Co-Founder of TrustaFact https://www.entrepreneur.com/article/238902

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Article 12 – Video Conferencing

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Volume 6, Number 2, 2020

Top 15 Tips for New Managers You were born to be a leader. It is your passion to take the knowledge and experience you have gained and share it with others. And now you have the opportunity to manage a team of your very own. New managers often enter their roles with a wave of emotions ranging from terrified to ecstatic. No manner of work experience can fully prepare you for what it means to be a team manager, but there are plenty of things you can do to get that much closer. Let’s take a look at 15 new manager tips to get you ready for your new role as the leader of a team. 1. Prepare Before the Promotion Most of the time people have a decent idea of when they will be getting promoted to a management position. If this is a goal for anyone who hasn’t reached this level yet, then it is crucial to your success to begin preparing for this role now. Take time to watch other managers, learn from them, and even take education courses on business management to get ready. 2. Always Be Learning Author Vernon Howard once said to “always walk through life as if you have something new to learn and you will.” Even as a manager, it is important to be humble and teachable. Those who you work with are always going to be better than you at something, so it is imperative to a manager’s success that they also be learning. 3. Focus on the Big Picture One of the most common new manager tips you will hear from senior-level management all the way down to coffee-running interns is to never micromanage your team. Instead, focus on the big picture of team productivity and simply be aware of what they must accomplish to reach deadlines. By allowing your team to manage themselves, you help to avoid the cycle of despair that comes with micromanagement. 4. Learn Leadership Skills Echoing what was said earlier in the area of learning, it is important to learn solid leadership skills. There are a plethora of leadership development books and websites out there, so it’s time to start reading. Countless successful leaders have taken the time to put their knowledge and experience out there for the world to see. 5. Minimize Meetings Remember those meetings you used to always complain about before you became a new manager? Don’t feel like you need to continue this trend and end up having meetings just to have meetings once you are in this role. If you can figure something out via email or another group collaboration tool like Slack, take advantage of that time-saving resource instead. 6. Get to Know Your Team Building a personal connection with your team members is a great new manager tip to learn how to be a more effective leader to them individually. Not only should you ask about their job responsibilities and career aspirations, but also ask about their family, lifestyle, and hobbies to develop a relationship of trust. Having occasional team building activities is a great way to get to know your team. 7. Be the Boss, Not a Friend Although you should get to know your team on a personal level, it is still important to realize when at the office you are their boss and not their friend. These types of relationships can cause feelings of bias or favouritism to arise in other employees, sparking problems for team morale. If you do develop friendships with others in the office, be sure to maintain professional interactions while on the clock. 8. Treat Every Team Member with Respect Aretha Franklin said it best when she sang the lyrics, “R-E-S-P-E-C-T. Find out what it means to me.” Respect means something different to everyone. As a manager it will be up to you to determine what that is and how to show it to each individual member of your team. Page 1 of 3

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9. Always Be Available You should always be easily accessible to your team with an “open-door” policy. Let them know the best way to communicate with you and be sure to always respond to their inquiries, issues, and concerns in a timely manner. This level of availability will garner respect and make it easier for your team to keep you in the loop on daily operations. 10. Become an Active Listener Eye contact, nodding your head, and watching non-verbal cues are just a few pieces of what it takes to be an active listener. One of the most vital new manager tips on this list is to pay close attention to your staff whenever they approach you for a conversation. Make a point to never interrupt them and always repeat back the key points they mention to affirm you heard what they had to say. 11. Stay Organized Maintaining an organized office, as well as keeping tasks on track will go a long way in boosting team productivity on a daily basis. Using tools like Toggl Plan’s project management software streamline these processes and help you manage every facet of your team’s to-do list. Once you have everything set up, you can then share these lists with your group. 12. Plan Ahead There are numerous quotes from famous individuals discussing the importance of planning ahead, but one of the most popular is by Benjamin Franklin when he said, “By failing to prepare, you are preparing to fail.” Another way Toggl Plan can help is by setting up plans, assembling timelines, and assigning responsibilities to specific team members. By planning ahead, you will keep everyone on the same page and avoid pitfalls that stem from a lack of preparation. 13. Do Performance Reviews Whether the company you work for requires them or not, you should always do individual performance reviews with each member of your team, at least once a year. This is not a time to tell them all the things they are doing wrong. These reviews are a time to recognize ways they are succeeding and offer motivational insight on opportunities for them to improve. 14. Ask for Feedback There are a couple of different ways to look at this new manager tip. You should constantly be asking your team for ideas and suggestions when it comes to business operations, strategies, and ways to improve the company vision. You can also view this as a means to ask for personal feedback and recommendations on how you can improve as a manager. 15. Lead by Example If there are any new manager tips worth listening to, it is to always lead your team by example. Avoid the “do as I say, not as I do” mind-set like the plague and ensure you are working just as hard, if not harder, than everyone else. This will generate a great deal of respect from your employees and motivate them to do their best. Written by Logan Derrick ǣȀȀ Ǥ Ȁ Ȁ Ǧ Ǧ

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10 Signs Of A Professional Midlife Crisis — And How To Get Through One A professional midlife crisis is not a rare phenomenon, especially for people who have been in the same job or industry for most of their career. While jumping into action and making dramatic life or career changes that haven’t been properly planned can do more harm than good, there are ways to identify a midlife crisis and smartly navigate your way through it to brighter days. If you feel stuck and as if you need to make a big change regarding your career, these 10 members of Forbes Coaches Council can help. Below, they share some key signs of a midlife crisis and tips for coming out of one stronger and more successful than ever. 1. If you have a fixed mind-set, reconnect to a higher purpose. A fixed mind-set that misses the many possibilities and opportunities to find new and better ways of working often is one sign of a midlife crisis. Habitually repeating safe and reliable processes over the years is a common trap for professionals, leading to a lack of inspiration. Reconnecting to the higher purpose of the work is the first step to burning bright rather than burning out. - Elisa Mallis, Center for Creative Leadership 2. If you're struggling to perform, learn something new. This "crisis" happens many times throughout life, and there are ways to spot and stop it. I can always tell who's struggling. They're not performing to their typically high standards, are working fewer hours and show little physical and mental energy. You can almost see the passion drain from their bodies. This is a great time to access professional and personal development options. Learning always helps! - Miranda VonFricken, Miranda VonFricken Masterminds & Coaching 3. If you’re asking whether that’s all there is, look inside. "Is that all there is? What's next for me? Why continue?" When you ask yourself questions such as these, it can indicate a midlife crisis. The more successful you are in your profession, the deeper the crisis can become. The key is to find your way back to your passion and identify your higher purpose, which can help you build a new chapter with more meaning. Find a professional who can help before blaming your partner. Mickey A. Feher, The MANTORSHIFT Initiative 4. If your inner voice is calling out, reengage with old passions. The “midlife crisis” is a calling back to one's inner compass. One of the key signs of this inner calling is your inner voice becoming more persistent as your ability and desire to ignore it begin to fade. The desire to learn new things or reengage with old passions emerges, and joy seems to reappear from nowhere. As a result, it is more of a coming home than a crisis. - Alexsys "Lexy" Thompson, Alexsys Thompson Intl 5. If you feel you haven't achieved anything, find alternative activities. I can share my personal experience: A significant sign is when I keep thinking that I haven't achieved anything in life until now. This very thought pushes one into nightmarish experiences. Luckily, I was able to realize this quite early on and started concentrating on alternative activities, such as practicing an endurance sport, which accentuated my professional life. - Sudhakar Reddy Gade, Nirvedha Executive Coaching Solutions Pvt Ltd 6. If you’re dissatisfied with life and work, write to uncover the truth. Dissatisfaction with life and work is a key sign that someone may be experiencing a midlife crisis. If you're feeling like a caged animal, write down your emotions. Then, clarify where these emotions are coming from, what is within your control and what you cannot control. Then, reality-check your answers. Often, we have a couple of facts, and we create a whole story around them. Uncover what is true. - Frances McIntosh, Intentional Coaching LLC

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Article 14 – Professional Midlife Crisis

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7. If you’re uncertain about choices, embrace discovery. One sign that professionals are experiencing a midlife crisis is when they feel uncertainty around their chosen profession, lifestyle or relationships and a willingness to toss it all in the bin on the path to “figuring it out.” My top tip for navigating through this phase is to not try to escape the identity crisis. Stay with the discomfort of "burning down to rebuild" and embrace acceptance as the discovery phase unfolds. - Jennifer Helene, Purposeful Ventures, LLC 8. If you’re exhausted or lethargic, focus on creating a healthier future. People going through a midlife crisis may show up as exhausted or lethargic. Often, sleep patterns are disrupted, and the mental energy needed during this major shift leaves little in the reserves for work, especially if it is repetitive or unchallenging. Avoid alcohol and other depressants and commit to daily exercise to increase serotonin. Seek out work opportunities that can move you into a great future. - Christine Rose, Christine Rose Coaching & Consulting 9. If you feel you’ve hit a wall, ask ‘how’ rather than ‘what’ questions. At some point, seasoned professionals will hit a wall and wonder, “What’s next? What else?” You may ask yourself a host of other "what" questions as you wonder. When feeling a need for clarity and purpose, both professionally and personally, take time to reframe your thinking by changing the type of questions you ask of yourself from "what" to "how." Think of ways to leverage your knowledge, skills and capabilities. - Sheila Carmichael, Transitions D2D, LLC 10. If you’re questioning everything, formulate a positive vision. A midlife crisis starts with questioning the meaning of what you do, what you stand for and, thus, which direction you want to take. This applies to both private and professional life. Therefore, it is important to find a positive vision in common with your team or the company. Formulate it together, deciding what gives purpose and what important contribution you can and would like to make. - Michael Thiemann, StrategyLab™ ǣȀȀ Ǥ Ǥ Ȁ Ȁ ȀʹͲʹͲȀͲͻȀʹͻȀͳͲǦ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ȁǫ αʹͻͻ ͵͸͹Ͳͺ

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Article 14 – Professional Midlife Crisis

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Volume 6, Number 2, 2020

Are Leaders Learning How to Be More Empathetic? If Not Now, When?

“I think we all have empathy. We may not have enough courage to display it” (Dr. Maya Angelou to the New York Times). With COVID-19 and racial justice issues taking centre stage, we need empathy more than ever. The ability to understand another person’s thoughts and feelings from his or her point of view opens the door to good working relationships, innovative business solutions and more inclusive societies. However, empathy is often misunderstood and undervalued. Realizing the benefits of empathy starts by clarifying what empathy actually is, why it matters and how we can learn it. Improving empathy is vital in our current circumstances. Displaying behavioural empathy has become more challenging in a remote workplace, as video-based technology is still not equivalent to face-to-face communication. Moreover, people are less likely to show empathy when it’s needed the most. In situations where people are feeling distressed or vulnerable, they are less open to understanding others’ perspectives; instead, they tend to defend their own perspective vigorously, escalating tension and conflict. Across the challenges of 2020, leaders have varied tremendously in how much they empathize with employees. We can see healthy levels of empathy in the leaders who checked in with employees, asked how they were doing and surveyed them on their concerns. In comparison, we saw underdeveloped empathy in leaders who wondered aloud, “why can’t John Smith work in the office tomorrow?” when John Smith didn’t have child care or previously relied on public transportation. Other leaders expected Black employees to be focused during the morning team meeting after the killing of George Floyd. In general, statements of “Why doesn’t …” and, “If it were me, I …” are signs of deficient empathy. What Is Empathy? Empathy often is misconstrued as “touchy-feely,” and leaders often believe that they show empathy when they put out carefully constructed statements in response to stressful events. These mistaken beliefs prevent leaders from fully engaging with the powerful skill set of empathy. The time is right to authentically listen to, understand and acknowledge employees’ perspectives. Page 1 of 3

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According to a recent review of rigorous organizational research, there are three types of empathy: 1. Affective Empathy Affective empathy involves experiencing others’ emotions. 2. Cognitive Empathy Cognitive empathy involves understanding others’ thoughts and feelings. 3. Behavioural Empathy Behavioural empathy refers to the verbal and non-verbal behaviours that indicate affective or cognitive empathy, including reflecting others’ facial expression, voice and gestures. This empathy also is conveyed through communication, such as verbally expressing understanding (e.g., paraphrasing), asking questions about another person’s thoughts or feelings, and non-verbal demonstrations of listening (e.g., head nodding). Does Empathy Matter at Work? Current research shows that cognitive and behavioural empathy make an impact in the workplace. One study found that individuals who displayed behavioural empathy were viewed as emerging leaders among their master of business administration (MBA) peers because they considered others’ perspectives. Other research suggests that workers with high levels of cognitive empathy are more likely to show compassion and help others. Regarding affective empathy, neuroscience research has shown that feeling pain with others activates the same regions of the brain as experiencing it first-hand. A compassionate reaction does not cause pain itself, but it does produce concern, warmth and motivation to help the sufferer. This finding suggests that there are great benefits from teaching individuals to focus on being compassionate. When their direct reports view them as more compassionate or “empathically concerned,” leaders’ supervisors rate them as better performers, less likely to derail and more skilled at giving negative feedback. As a recent example, as of May 2020, U.S. states with female governors have had fewer COVID-19 deaths than states with male governors, and an analysis of 1.2 million words of transcripts found that the women expressed more empathic concern in their briefings, demonstrating the importance of leaders’ ability to demonstrate empathy. Can People Learn Empathy? Although individual people’s baseline empathy varies naturally, evidence suggests that they can improve it. For example, a lab study increased cognitive empathy by instructing individuals to “feel the full impact of what the other person is going through.” These individuals then delivered negative feedback in a way that was viewed as more fair and just. Many leadership development consultants see growth among leaders who deliberately work on strengthening specific aspects of empathy. Effective change starts with the motivation to improve, which often comes from learning how empathy contributes to positive outcomes for individuals and the organization. Next, distilling empathy into small behaviours helps leaders practice during training and then on the job. For example, empathic communication involves actively listening (i.e., being attentive, summarizing, clarifying, paraphrasing, etc.) and engaging others through powerful questions (e.g., open-ended rather than leading or yes/no questions; avoiding jumping into problem-solving, and exploring the situation by asking, “What is your goal?”). Perspective-taking is another best practice. It involves pausing and creating space to respond thoughtfully rather than reacting impulsively. This skill involves thinking through others’ expectations before meetings; pushing oneself to find additional ways of viewing a situation; and staying curious about another person’s viewpoint, rather than judging or becoming defensive. Although simple, these skills take time to develop through deliberate and regular practice on the job. Asking for feedback from a trusted colleague and regular self-reflection are tactics that help empathy improvements “stick.”

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How Can Organizations Foster Empathy? Context sets the stage for success or failure. Therefore, organizations that set up contexts that promote behaviour change will be more successful. Rather than assuming leaders will develop the skill of empathy with brief training, applying evidence-based strategies enables organizations to create local contexts to weave empathy into everyday interactions. First, the management team visibly needs to support understanding, developing and practicing empathy at all organizational levels. Senior leaders create the systems that promote (or prevent) empathy. They can’t afford to outsource this work to the human resources department. Second, adding empathy to reward systems puts “teeth” behind leaders’ words about empathy’s importance to the organization. Third, developing empathy requires new processes and resources. Offering formal empathy training and “inthe-flow of work” coaching helps employees learn and practice new empathic behaviours on the job. Fourth, it’s a good idea to ensure that your organization is hiring people with the knowledge and skills needed to actively engage in developing empathy. Specifically design organizational talent systems to attract and reward people who are learning-oriented and motivated to expand their capabilities. Finally, regularly communicating the value of developing and practicing empathy can include publicizing initiatives, celebrating good examples of empathy, and sharing mistakes and lessons learned. What Would Change If Leaders and Organizations Prioritized Empathy? Empathic behaviours would pay off in both the short and long term. McKinsey reports that demand for emotional and social skills will increase as artificial intelligence (AI) and robotics automate more work. When working with other people, understanding their thoughts and feelings is essential for successful coordination. Behavioural empathy is, as a result, often critical to team performance and personal success. If we take empathy seriously, solving seemingly intractable problems like systemic racism would be easier because more people would be equipped for difficult conversations and taking action. Few problems have “silver bullet” solutions, but increasing empathy improves the odds of creating and sustaining real change that benefits us all. Stephen Young, Ph.D., and Cathleen Swody, Ph.D. ǣȀȀ Ǥ Ȁ Ȁ Ȁ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ǧ Ȁ

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Volume 6, Number 2, 2020

PITA CENTENARY PART 1: BIRTH OF THE TECHNICAL ASSOCIATION Daven Chamberlain, PITA Publications Editor 1

Prehistory The traditional date and place given for the development of paper is 105AD in China. In fact earlier samples of ‘proto-paper’ have been unearthed by archaeologists, and indeed dating the commencement of a craft like paper manufacture is not an exact science. Nevertheless, first century China will do. What is more certain is that for almost a thousand years it stayed in the Far and Middle East, only reaching the shores of Europe in the eleventh or twelfth centuries when it was brought to Spain by the Moors. It then limped across Christian Europe at a slow pace, crossing the English Chanel at the end of the fifteenth century. The process of inculcation commenced with introduction of the material by an outside agency, followed by assimilation through imports, before indigenous manufacture commenced. So for the UK, the earliest paper found in the Public Record Office dates from about 1220, yet the first mill commenced in the 1490s. In some ways the UK was a ‘special case’ because at this period it was a major producer and exporter of wool, and sheepskin parchment was therefore readily available and the medium of choice for written communication and record keeping. The first paper mill, in Sele, Hertfordshire, did not last long, and although a few examples did crop up at various sites in the sixteenth century, it was not until the 1600s that a native UK industry took hold properly. Throughout this time start-ups were based largely in England, and spread only slowly to Ireland and Scotland (both by 1590), and finally to Wales (possibly 1650s, certainly by 1706). Ironically, given that the first English mill made white printing paper, the vast majority of that produced by the burgeoning industry was the much simpler brown grades used for wrapping purposes; the country imported the majority of high quality white grades from France, Italy and the Netherlands until well into the eighteenth century. 2

Notable Inventions and Achievements Although it was rather ‘late to the table’, the inventiveness of the UK populous did take hold of the craft eventually. Notable achievements were the development of a smooth (wove) surface by James Whatman in the 1750s, which gave much-improved print quality over the more textured laid sheet that had hitherto been made. Then, although the outline design for a mechanised method of paper manufacture had been produced in Revolutionary France, it was brought to fruition and commercialised (in Frogmore Mill, Hertfordshire, 1804) thanks to English engineering skill in the form of John Hall and Bryan Donkin, along with finance from the Fourdrinier family, who added their name to the first design. Just along the way from Frogmore lay Apsley Mill, owned by John Dickinson, and in 1809 he patented his rival design, the cylinder mould; together these two machines were to revolutionise the industry, although neither as yet offered the potential to form a dry web; in both designs the wet web, after pressing, was reeled on a drum, then slit with a sharp knife to yield sheets that could be hung in a loft, as per the standard handmanufacturing process. This was changed with the development of steam-heated cylinders, patented by Thomas Bonsor Compton in 1821. Soon after, in 1825, the dandy roll was patented by John and Christopher Phipps (although a rival patent by John Marshall also dates from around this time). The necessary components for a machine to produce a continuous, dry web of paper which could, if necessary, be watermarked, were now in evidence, and the industry could therefore develop … except for the minor problem of raw materials. Although papermakers in the East used raw trees and plants as their raw fibrous material for paper manufacture, in the West textile rags had been the source of choice from the start. However, availability of rags (made originally from hemp or linen, with cotton being introduced much later) proved a brake on development of the industry. Even when papers were made solely by hand, the UK had to import much of the raw materials from mainland Europe. Now that a machine had been produced, which had the potential to ramp up production significantly, the lack of high volumes of a reliable fibre source became a major hurdle.

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At various times in the eighteenth century, scientists in several countries experimented with different plant materials, including reeds, straw and nettles, but none were particularly successful until a method for pulping Esparto (Spanish Reed) was developed around the 1840s, before being perfected by Routledge in the 1850s at Eynsham Mill in Oxfordshire. In the meantime, groundwood pulp was developed in Germany during the 1840s by Keller, but it wasn’t until the 1860s that the first chemical wood pulp was made, via the soda process (developed at Boxmoor Mill in Hertfordshire by Burgess and Watt in 1851, but commercialised properly the following decade in America). In subsequent decades the sulphite then sulphate (Kraft) processes were developed, ultimately leading to the pulp industry based upon wood that we know today. 3

Combinations and Associations So far the text has concentrated upon the major technical developments in the industry, many of them stemming from the UK. However, an equally important factor in this story is that of social conditions, caused by the Industrial Revolution that took place in the United Kingdom from about 1760 onwards. Prior to this, manufacture was performed by artisans, often in their own homes; volumes were small and articles expensive. With the development of steam power (which, incidentally, was first applied to papermaking at Wilmington Mill in Yorkshire, around 1786) it became possible to mechanise production in larger premises, and the factory was born. This in turn caused major social upheavals as families moved from rural to urban locations, and thus towns and cities swelled and working conditions deteriorated. In order to protect themselves, workers banded together in Combinations (early forms of Unions), and demanded political reform. Although these gatherings were illegal, and were often put down violently (one of the most famous instances being the Peterloo Massacre of 1819 in Manchester), nevertheless the brave workers did eventually gain the right to form unions. In the UK the earliest example was the Original Society of Papermakers (1800), followed later on by the United Brotherhood of Paper Makers (1854) and the Modern Society of Paper Makers (1869) – two unions open to machine paper operators. The Manufacturers were wary of the strength that Combinations gave their workers, so themselves banded together to present a common front. However, just as in the case for workers, it was also illegal for Manufacturers to operate in this fashion, yet they did so, albeit their efforts were not always that efficient or long-lasting. (Yet they did have the advantage of not having their meetings disrupted by violence.) 4

Trade Bodies The earliest of these Trade Bodies was the Paper Makers of Great Britain (1764). This was followed by the Master Paper Makers of England, and a possible break-away unit, the Master Paper Makers of Kent, at the turn of the nineteenth century. The Manufacturers of Paper and Pasteboard in England and Wales was formed by John Dickinson in 1831; the Paper Makers’ Association in the 1850s; and the Lancashire and Yorkshire Paper Makers’ Association in 1863. A feature of all these Associations was their short duration; they were generally formed for a purpose (such as to fight for reforms to Excise duty) yet they never gained much traction, membership was disparate with only a limited number of manufacturers in any one region showing support – and without exception, all failed. Until, that is, in 1872, when the Paper Makers’ Association of Great Britain & Ireland (hereafter PMA), was formed. This was the first truly national body, although note the absence of Scotland – makers there formed their own Association, which remained separate until incorporated in 1912. In turn this became the British Paper & Board Makers Association (BPBMA) in 1949, the British Paper & Board Industry Federation (BPBIF) in 1974, the Paper Federation (1994) and, most recently, the Confederation of Paper Industries (CPI) in 1999. Over the years the various Trade Associations have collated statistics, lobbied Government and provided a voice for the industry as a whole. However, it was during the aftermath of World War I that the PMA conceived the need for a Technical arm to their work. Almost certainly this is because they had seen how the industry has fared during the war – prior to WWI the UK as a whole had imported huge amounts of chemicals and special papers, primarily from Germany, and following the outbreak of hostilities this trade ceased and indigenous companies had to develop the technical expertise needed to plug gaps, especially for such specialities as photographic and tracing paper grades. Technology was seen as vital to the future prosperity and development of the Industry, and so we come to the start of the Paper Industry Technical Association (PITA) story with the inauguration of the PMA Technical Section as an adjunct of the national Trade Association – the development of which will be described in subsequent articles.

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PITA CENTENARY PART 2: WHEN ART MET SCIENCE Daven Chamberlain, PITA Publications Editor 5

The previous article highlighted the events that led prior to formation of the Papermakers’ Association Technical Section (which morphed eventually into the modern Paper Industry Technical Association – known more widely as PITA). This new article will follow some of the events and issues faced by the Technical Section (hereafter ‘Section’) during its first forty years (1920-1959) – the period immediately prior to the introduction of Paper Technology as the new flagship publication. The period after WWI saw major developments in most industries, as science was used to evaluate and improve all sorts of manufacturing processes. However, the transition from an artisanal operation to a scientific endeavour was not without problems. For instance, as was noted by Hugh Rutt (Chairman, 194850) “The industry after the First World War was still run by practical paper makers and engineers. There were very few chemists – in fact they were regarded as rather queer fellows who came forward with all sorts of untenable theories. The truth is that most paper makers at that time simply did not understand what the chemists were talking about. Consequently, if a man was a chemist, he was apt to be regarded with 6 suspicion.” However, the advance of scientific methods into papermaking was thanks in no small part to the Technical Sections of the UK and other national organisations – most notably those in Canada (founded 1915), Finland (1914), Germany (1905), Sweden (1908) and USA (1915). These all provided a forum for discussion and dissemination of scientific ideas and principles, along with journals for publishing research. Also, it is thanks to the work of these bodies, that national and international standardisation of testing methods entered our industry. th

In the UK, the embryo Section grew from a meeting that took place on 5 March 1920 at the Midland Hotel, st Manchester. A Committee was formed and invitations issued to membership on 31 March 1920, a st th Constitution was adopted on 21 April 1920, and the first General Conference held on 8 October 1920, 7 although a local branch in Aberdeen had started meetings prior to this. Local branches then formed in Manchester and London. In a relatively few years local divisions were formed in London, Manchester, Scotland, and eventually, the West of England, and biannual national conferences started, one in London and the other in either Edinburgh or Manchester, which provided ready material for publication. From the start it was noted that to make real progress as an industry, it would be necessary to adopt modern ideas about science and engineering, and to cease the empiricism that had hitherto formed the basis of the 8 craft. However, mere academic training was deemed of no practical use. Rather, the scientist or engineer needed training in the special aspects of the trade, while the practical craftsmen needed some grounding of a more academic nature. This all required revision of the current training offered to industry members, therefore a major feature of the early years of the Section involved modernisation of the City and Guilds 9 Examination curriculum to make it fit for purpose. Four levels of membership were on offer from the very beginning: ‘Ordinary Members’ were employees of paper mills; ‘Associate Members’ were employees of allied firms (suppliers); ‘Junior Members’ were those under 25 years of age, employed either by paper mills or allied companies; and ‘Corresponding Members’ were those resident abroad. In addition, occasional ‘Honorary Members’ were voted in, the first such being 10 C.F. Cross of Cross and Bevan. While ever the distinction persisted between the different levels of membership, ordinary ‘Ordinary Members’ predominated, followed by ‘Associate Members’. Finally, a new 11 category, ‘Corporate Members’, appeared from 1934. Dissemination of information was also a priority; local meetings offered fellowship and networking opportunities, but without publication of the work to reach a wider audience progress would be limited. So, transcripts of the various presentations, many of them important reviews or in-depth research papers into different practical aspects of papermaking, scientific investigation of testing methods and procedures, philosophical tracts on the role of science or of management in the industry, and works on statistics, education, and even history, were published in the well-known series Proceedings of the Technical Section, bound from the start in the characteristic orange card covers – which may offer a clue as to the origin of the orange cover associated with Paper Technology. Seminal early works included James Strachan (Chairman,

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1940-42) on “The Hydration of Cellulose in Papermaking” (1926) and “Further Notes on the Hydration of Cellulose in Paper Making” (1932), and the First and Seconds Reports of the Paper Testing Committee to the Technical Section – the First Report produced the early British Standards for a wide variety of common 12 paper test equipment, and the Second Report outlined the handsheet making process still used today. In addition to the Proceedings, a Bibliography of Periodical Publications on Papermaking and Allied Subjects 13 was produced annually from 1921 onwards, and from 1924 a monthly Technical Abstracts publication 14 15 started, which changed name to the Technical Bulletin a decade later. The Bulletin became the ‘house’ journal of the Section, containing news, articles, and extended abstracts from foreign journals, and lasted into the 1950s. Also, ad hoc publications appeared over time, such as For Your Safety, and the textbook Papermaking. The minutes of the Annual General Meetings were also published in these Proceedings, which contain much interesting detail about the Section (such as membership numbers – see Figure 1), in addition to general items of interest, including: problems of selling technical textbooks (nothing changes!); the fact that University College, London, was the site where much of the early research undertaken by the Section was 16 17 performed; the establishment of a library at the Association headquarters in Farringdon Street, London; and presentation by Messrs. Walmsley (Bury) Ltd of a new Paper Machine to Manchester College of 18 Technology (which became UMIST).

Figure 1:

Graph showing the growth in membership over the first six decades of the Section.

In particular, the period during WWII was obviously very difficult for the Section; membership declined and the Proceedings were noticeably thinner. However it is interesting to note that some highly topical presentations were published at this time, such as on problems to do with quality and availability of waste 19 paper. The Section also consulted upon increasing production of boards and encouraging use of waste 20 21 paper, and then on use of alternative fibre resources. Interestingly, it is during this period that the 22 purchase of the Clayton Beadle Collection of Watermarks for the Technical Section’s Library was made; one cannot help but wonder whether this was in part to save it from being pulped! Also noted in the Section 23 minutes is the sending of technical literature on papermaking and allied trades to prisoners of war, apparently enabling them to undertake study in papermaking technology in the various camps in Germany 24 and Italy.

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In 1945 is recorded the instigation of the Section’s first award – a medal (the Silver Jubilee Medal – see Figure 2) donated by Arthur Baker, the first Chairman (1920-1922). It was first awarded in 1947, to S.R.H. Edge (Figure 3) of Wiggins Teape, for his activity within the Section since joining in 1924, and the large number of publications he produced, which commenced in 1928. There is some irony that the dedication read by Mr. Baker himself during the presentation concluded with the line, “I hope that you will live many 25 years to give us the benefit of your help in the Section;” only a few years later Mr. Edge was dead after 26 having suffered ill health for a protracted period. Also recorded alongside the death of Mr. Edge at the same AGM was instigation of another new award, bequeathed by Major Renold Marsh; this was to be aimed at young members, who were required to produce a technical essay. The first recipient was A.P. Gammie 27 (Figure 4), a trainee at Bowaters Kemsley Mill, in 1956, for an essay on broke handling. However, just three years later it was recorded with disappointment the paucity of entries for this prize, even though it 28 offered a cash amount of £40 (equivalent in 2020 to around £1000).

Figure 2:

The Silver Jubilee Medal, instigated by the first Chairman, Arthur Baker.

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Figure 3:

S.R.H. Edge, first recipient of the Silver Jubilee Medal.

Figure 4:

A.P. Gammie, first recipient of the Marsh Prize.

After the War the Section decamped from London to the British Paper & Board Industry Research 29 th Association premises at St. Winifred’s, Kenley. However, a fire on the night of 7 November 1949 at the 30 Kenley site “destroyed practically the entire Technical Section library, offices and records.” Temporary quarters were set up elsewhere on the site, allowing for reconstruction to take place, and the Section set about trying to recreate its lost library with donations from around the world. Going into the 1950s, the minutes record two important events, the first being formation of a new ‘special 31 interest group’, the Fundamental Research Committee. The importance of research to the health and prosperity of the paper industry was one of the reasons for founding the Section just after WWI. Go forward three decades, and there was a realisation that applied research was not enough; there were fundamental Page 6 of 15

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(or ‘blue-sky’) problems which needed to be solved in order to allow applied research to progress and new ranges of products to be produced. The FRC held their inaugural conference in 1957 in Oxford, after which it 32 has been held every four years, alternating between Oxford and Cambridge. The top research scientists from around the world attend and its proceedings rank as some of the most important in the field of paper research. 33

The second event was formation of a museum committee, dedicated to saving the heritage of our industry. This may seem a strange subject for a ‘technical’ organisation, but again, going back to its inauguration, the Section stated that history was to be part of its aims. Indeed, a paper in the first Proceedings was on exactly 34 this subject area. The Chairman was J. Barcham Green, and the stated aim was to find suitable accommodation for a National Paper Museum, within fifty miles radius of London. The Museum committee made no great headway until the next decade, so the next article will pick up this strand of the story. But as we come to the end of the period covered by this article, trouble was in store for the Section. The Research Association was thriving, and needed to expand, so they asked the Section to vacate premises by 35 June 1960. It then came to light that the Section had been paying a peppercorn rent of some £300 per annum, and to stay in the immediate area was calculated to cost ten or twenty times this amount. The end point of this part of the Section history has now been reached. Having survived four decades, covering inception, the Great Depression and a World War, the future was now in doubt as financial hardship loomed. History tells us that it also marked the final publication of the Proceedings; but a new and successful chapter was about to dawn, as will be described in the next part of this series.

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PITA CENTENARY PART 3 (1960-1999): TOWARDS A NEW MILLENNIUM Daven Chamberlain, PITA Publications Editor The first article in this series described the events that led to formation of the Papermakers’ Association 36 37 Technical Section, and the second covered the first 40 years of the Section up to the end of the 1950s . 38 This article highlights what happened between then and the turn of the new millennium. At the end of the last part I reported that the British Paper & Board Industry Research Association informed the Technical Section that they would have to depart from the Kenley site, where they had been in temporary residence since around 1948, and find a new home. The Section was given until June 1960 to move, but in fact received a reprieve and didn’t decamp until mid-1961, when they transferred to Fetter Lane, near Fleet Street, London. Any move is not without problems, and in this instance the Section lost half of its staff in the process. Nevertheless, membership was increasing (Figure 5) and things generally looked on the up.

Figure 5:

Technical Section membership to 1972 (when publication of the figures within the journal ceased).

The period in question was also momentous for another reason: the well-respected Section Proceedings were replaced by a new magazine: Paper Technology. Initially issued bi-monthly, this replaced all of the Section’s publications and featured original technical articles, copious advertising, some Section news along with very limited industry news, all presented in a new, crisp, more modern format. Gone were the technical articles that could reach 20-30 pages in the old proceedings; now authors were required to restrict their writing to within five pages or so (much as they still are today) in a magazine format that had a distinctly commercial edge compared to the rather dry and academic format of the Section Proceedings. In fact, over the years the style of the magazine changed a number of times, as did the cover style (see Figure 6). From its launch in 1960 until April 1974 it tended to have a coloured cover of plain design, Page 8 of 15

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punctuated between 1965 and 1970 and then for occasional issues in the early 1970s with photographic images. Then, in 1975 it changed name to Paper Technology & Industry (for reasons explained later in this article), and from the June/July edition of 1976 there was a design change with colour images on the front surrounded by a strong orange border that has been its signature colour ever since. Indeed, since that date, it only changed colour for a couple of issues: May/June 1977 when it was silver to mark the Queen’s Silver Jubilee, and May/June 1978 when it was coloured green in an edition majoring upon waste paper and environmental issues.

Figure 6:

Montage of magazine covers from 1960s to 1990s.

Industry Past and Present Early in the period under discussion, in 1963, Prime Minister Harold Wilson gave his “white heat of technology” speech, and hopes were high that science and engineering, which had been a strong focus 39 since the formation of the Technical Section in 1920, would become ever more important, displacing the old ‘art of papermaking’. Hot topics in the magazine at this time were computers and automation, both then in their infancy but ready to assume massive importance in the years to come; metrification (articles started to appear in the early sixties, almost a decade before the change would take place nationally); recycling and deinking; paper-machine design and technology; and testing. Indeed, seen in retrospect this was the last golden period for building new mills, which included: Thames Board Workington (1966 – now Iggesund); Wiggins Teape Fort William (1966); Bowater-Scott Corporation Barrow (1968 – now Kimberly Clark); Kimberly Clark Prudhoe (1971); UPM Shotton (1983); UPM Caledonian (1989), and Leicester Paper Company (1998 – now Sofidel). In addition, the number of new machines installed in pre-existing mills, and machine rebuilds, was legion. But as one manufacturer of environmental chambers ruefully once remarked to me: “every silver lining has a cloud.” New mills were built, and new machines installed, but old mills were closing at a more rapid rate. We started the period will well over 200 manufacturing sites; in the forty years covered by this article, we lost over half (Figure 7). The ‘white heat’ of the 1960s gave way to the ‘lame ducks’ of the 1970s, which Edward Heath tried to keep afloat, before Margaret Thatcher allowed market forces free reign during the 1980s, and UK 40 manufacturing industry reacted accordingly by closing in large swathes. In particular it was the old, small,

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speciality mills that ceased to operate, and while paper usage showed unerring increase (so much for the ‘paperless office’) the actual range of papers used shrank significantly. Gone were the esparto printings of the Scottish mills, a vast range of industrial grades, and eventually most of the coated publication products. Gone also were some of the great names, such as: Bowaters, John Dickinson & Co., Reed Paper Group, and Wiggins Teape Group – all victims of merger, acquisition or consolidation.

Figure 7:

Number of UK Mills 1960-1999 (as published in trade directories).

A further casualty of the closures and concomitant job losses was the education sector. As noted in the first of these articles, education was deemed an important area for the Technical Section to improve. City and Guild examinations continued, and there were three establishments where higher-level studies were taught: Manchester Municipal College of Technology which gained a Royal Charter in 1955 to become Manchester College of Science and Technology, then the University of Manchester Institute of Science and Technology (UMIST) in 1966; Bury Technical College, which became Bury College in 1987; and Robert Gordon’s Technical College, which became Robert Gordon’s Institute of Technology in 1965 and Robert Gordon University in 1992. Job losses meant fewer students. Investment was poured into UMIST and Robert Gordon 41 University (Figure 8) in the 1990s, but ultimately it was too late. Industry Contraction Hits Home Shrinkage of the industry had a knock-on effect on the Technical Section. In 1972 the British Paper and Board Makers’ Association (BPBMA) celebrated its centenary; two years on it merged with the Employer’s 42 Federation to become the British Paper and Board Industry Federation (BPBIF); at this juncture the Technical Section, which was transferred to the newly-formed Commercial Division, was renamed the Technical Division. Soon after, at the start of 1975, the magazine was renamed Paper Technology & Industry, probably to indicate its more commercial alignment. Less than a decade later, the BPBIF decided that a Technical Division did not sit well within its future plans, so the two split in 1982, and the Division (which was afterwards renamed the Paper Industry Technical Association) became (loosely) assimilated into the Paper Industry Research Association (PIRA) based in 43 Leatherhead. This was never meant to be a permanent situation, but was very-much a necessary move in order to allow PITA time to reorganise and plan a new course.

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Things were actually quite dire at the time. Indeed, they got so bad that in 1984 two editions of the journal (No.3 and No.4) were never issued. Don Attwood, of PIRA, (Figure 9) took over editorship of the magazine from issue No.5 in 1984, replacing R. Maxwell Fendt who transferred over to ‘advertisement editor’; but Don was a very busy man, and this was certainly not part of his ‘day job’, so a search was initiated for a safe pair of hands which resulted in the appointment of Margaret Marley (Figure 10), who became editor from early 1986 (Figure 11). Move on three more years, and the name of the magazine was again returned to Paper Technology from the February 1989 issue.

Figure 8:

The heads of four Scottish paper mills view the pilot paper machine at Robert Gordon University, during a meeting where John Kirby (Managing Director of C. Davidson & Sons) handed over a cheque for £100,000 to help develop facilities.

Figure 9:

Don Attwood.

Figure 10:

Margaret Marley: the longest serving editor of the magazine (1986 to 2009).

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EDITOR Francis M. Bolam R.L. Ballard J.M. Wilson R.S. Maxwell Fendt Don Attwood (acting) Margaret Marley Figure 11:

Editions Edited Feb. 1960 – Apr. 1970 June 1970 – Oct. 1974 Dec. 1974 – Sept. 1976 Oct. 1976 – Apr. 1984 Aug. 1984 – Dec. 1985 Feb. 1986 – (Dec. 2009)

Magazine Editors (period 1960-2000).

Behind the scenes, despite much discussion, PITA and PIRA remained together a decade; Don Attwood, and PITA Manager Tom Bolton, were two significant personalities that kept the ship afloat during this long association. Upon the final dissolution, in 1994, PITA left its home in Surrey and went north to its current 44 residence, in Bury, under the direction of John Clewley (Figure 12), its new Executive Director. The move meant that long-time Surrey office staff members Lesley Heard and Tara Doyle left, to be replaced in Bury by 45 46 Sandra Evans and Joanne Jost, and a year later they were supplemented by ‘Girl Friday’ Helen Sudhurst, who would in time marry John Dolan – and the rest, as they say, is history. (Helen Dolan is the longest serving PITA staff member, and has just celebrated her own Silver Jubilee! - DCC)

Figure 12:

L to R: John Clewley (PITA Executive Director 1993-2007), Sandra Evans, Joanne Jost and Helen Sudhurst.

To conclude this part of the story, having weathered two brutal recessions that saw significant mill closures in the 1970s and 1980s, being cast adrift from its founding Association, and faced with an ever-shrinking workforce from which to draw membership, PITA got to the new millennium in much better shape than it had been for some time. With eight decades already behind it, what would the new millennium hold? Appendix 1: Paper Museum – Rise and Fall In 1957 a committee was formed to organise a national museum dedicated to the industry. The Trust Deed was drawn up by April 1960, the three trustees being H.R. Balston, Rémy Green, and P.H. Prior, and it was reported that offers of old machines and apparatus had been received and earmarked for the museum; 47 indeed, it was hoped that these would include the experimental Inverform machine. In less than a year a site was found: Joynson’s Mill, St, Mary Cray, operated by Wiggins Teape Group under 48 the auspices of Vegetable Parchment Mills (Delcroix) Ltd. The following chief exhibits were held: Hand Press; Waterleaf Dryer; Waterwheel; Rag Beater; Mould Rinsing Tank; Wooden Rag Duster; Stamper for Washing Felt; Stuff Chest and Vat Pump; Vat with Agitator and Bridge; Couch Stool, Felt Stool and Ancillary Drying Equipment; Rag Boiler; Copper Vat Heater; Strainer; and Dandy Roll. There was also a model of the press part of a Fourdrinier machine, and an exhibit recounting development work on the Inverform machine. So it is immediately obvious that the vast majority of exhibits related to hand manufacture of paper; there was little noted as regards machine making. Page 12 of 15

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The museum was opened on 24 April 1963 by G.B. Johnston, chairman of the BPBMA. By 1966 work was still being undertaken to catalogue the museum library, which was still not open to the public; but the museum itself was receiving visitors, and a new exhibit was noted to be an 8mm film of hand-making at 50 Hayle Mill. But the situation changed in 1967 with the sale of the mill site, and the emergency removal of 51 exhibits during December of that year was noted, along with the search for a new site. By the turn of the new decade it was noted that the exhibits had been received at the Manchester Industrial Museum, which 52 was hoped would be a temporary home before a new permanent site could be identified. (In fact, this is still the home of the exhibits today; no new site could be found – DCC). [These three articles are extended versions of what appeared originally in the PITA Annual Review 2019/2020 and Paper Technology International. They are published elsewhere in The Quarterly: Journal of the British Association of Paper Historians.]

Notes and References 1 . Hunter, D., Papermaking: The History and Technique of an Ancient Craft, Dover Publications Inc., New York, 1978. 2 . Hills, R.L., Papermaking in Britain 1488-1988, The Athlone Press, 1988. 3. Stirk, J.V., Industrial Relations in a Craft Trade: The Original Society of Papermakers 18001948, BAPH Studies in Paper History, Volume IV, 2016. 4 . Muir, A., The British Paper & Board Makers Association 1872-1972, privately printed. 5 . PITA Annual Review, 2019-2020, pp.20-21; The Quarterly, No.114, Apr. 2020, pp.29-31. 6 . Muir, A., The British Paper & Board Makers Association 1872-1972, 1972, p.37. 7 . Foster, A.W., “History of the Formation of the Technical Section of the Papermakers’ Association”, Proceedings, Vol.1, 1921, pp.5-6. (Mr. Foster was the first Secretary of the Section.) 8 . Baker, A., “Chairman’s Address”, Proceedings, Vol.1, 1929, pp.10-13. 9 . Nuttall, W.E., “The Chairman’s Address: The Future of the Technical Section”, Proceedings, Vol.3, 1923, pp.13-19. 10 . “Constitution and Rules”, Proceedings, Vol.1, 1921, pp.106-108. 11 . Proceedings, Vol.15, Oct. 1934, Part I. Unfortunately, AGMs were not published in Vol.13 and 14, so the exact date when a resolution was passed to form this category is not obvious. 12 . Proceedings, Vol.18, June 1937, Part 1A. 13 . AGM, 23 Mar. 1922, Proceedings, Vol.3, Oct. 1922, Part I. It was certainly published into the 1930s, maybe further, but mention ceased quite quickly in the AGM minutes. 14 . AGM, 22 Mar. 1923, Proceedings, Vol.4, Sept. 1923. Part I. 15 . AGM, 21 Feb. 1934, Proceedings, Vol.15, Oct. 1934, Part I. 16 . AGM, 27 Mar. 1924, Proceedings, Vol.5, Sept. 1924, Part I. (The textbook in question was a translation of Dr. Sigurd Smith’s Theory of Beating.) 17 . Sixth General Conference, 26 Oct. 1922, Proceedings, Vol.3, Mar. 1923, Part II. (This volume also contains a list of some of the books contained in the library, including a large number presented personally by Mr. Lewis Evans.) The books were available to loan to members, and in time, technical journals from other organisations formed part of the holding. 18 . AGM, 8 Mar. 1939, Proceedings, Vol.20, Oct. 1939, Part I. 19 . See for example: Sheldon, G.H., “Business in War Time”, Lund, F., “War-Time Papermaking”, and Potts, T.T., “Safety in War Time”, Proceedings, Vol.21, Oct. 1940, Part I, pp.239-247; Cameron, D., “Some Aspects of War-time Papermaking”, Proceedings, Vol.23, Dec. 1942, pp.176-191. 20 . AGM, 5 Mar. 1941, Proceedings, Vol.22, Dec. 1941. 21 . AGM, 10 Mar. 1942, Proceedings, Vol.23, Dec. 1942. The minutes state that work was performed upon artichoke stems, baobab fibre, hop vines, marsh grass, sunflower stems and tomato stems. Page 13 of 15

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22 . AGM, 13 Mar. 1940, Proceedings, Vol.21, Oct. 1940, Parts I & II. 23 . AGM, 10 Mar. 1942, Proceedings, Vol.23, Dec. 1942. (These minutes also record that Colonel William Nash was a PoW, and had been instructing fellow prisoners on the subject of factory administration and management.) 24 . AGM, 10 Mar. 1943, Proceedings, Vol.24, Dec. 1943. 25 . AGM, 17 Mar. 1948, Proceedings, Vol.29, June 1948, Part I. 26 . AGM, 21 Mar. 1956, Proceedings, Vol.37, June 1956, Part II. (He died in December 1955.) 27 . Gammie, A.P., “Development in Newsprint Broke Handling”, Proceedings, Vol.38, June 1957, Part II, pp.439-447. Cash equivalence calculated using website www.measuringworth.com. 28 . AGM, 25 Mar. 1959, Proceedings, Vol.40, June 1959, Part II. (It is worth noting that the successor to this award, the Julius Grant Prize, which is still on the books of PITA today, suffers from the same problem – lack of interest from the target audience.) 29 . AGM, 17 Mar, 1948, Proceedings, Vol.29, June 1948, Part I. 30 . AGM, 15 Mar. 1950, Proceedings, Vol.31, June 1950, Part II. 31 . AGM, 21 Mar. 1956, Proceedings, Vol.37, June 1956, Part II. Mention of the special committee formed for this purpose certainly pre-date this minute, but an earlier one cannot be identified. In a special report for the year 1956, Proceedings, Vol.38, June 1957, Part II, it was stated that the Committee was formed in 1955. Meanwhile, the first Chairman, Dr. Toby Rance, wrote a history of the FRC where he stated that its formation dated from late 1954: Rance, H.F., “History of the FRC – a committee of the Pulp and Paper Fundamental Research Society”, Paper Technology, Vol.38, No.7, Sept. 1997, pp.24-26. 32 . The ‘Committee’ is still inexistence: see ‘FRC – The Pulp and Paper Fundamental Research Society’, www.ppfrs.org. 33 . Autumn General Meeting, 29 Oct. 1958, Proceedings, Vol.39, Dec. 1958, Part III. 34 . Gray, J.N., “The Old ‘Hand-Made’ Paper Industry”, Proceedings, Vol.2, 1921, Part I, pp.8693. 35 . Autumn General Meeting, 21 Oct. 1959, Proceedings, Vol.40, Dec. 1959, Part III. 36 . PITA Annual Review 2019-2020, pp.20-21; The Quarterly, No.114, Apr. 2020, pp.29-31. 37 . Paper Technology International, Vol.61, No.2, 2020, p.33; The Quarterly, No.116, Oct. 2020, pp.36-39. 38 . An edited version of this article appeared in Paper Technology International, Vol.61, No.3, 2020, pp.26-27. 39 . The Golden Jubilee edition of Paper Technology, Vol.11, No.3, 1970, is an excellent repository of information, and reproduces many papers form the Ninety-Ninth Annual Conference, “The British Papermaking Industry – Technical Progress over the past 50 Years, Present and Future Developments”. This includes Prior, P.H., “The Beginnings of the Technical Section”, pp.179-182; and Wrist, P.E., “1920-1970: A Technical Perspective”, pp.182-187. 40 . For example, a million tonnes of production capacity was lost in 1980 alone: Paper Technology, Vol.22, No.4, 1981, p.110. Production in 1979 was 4.2Mt (Paper Technology, Vol.21, No.4, 1980, p.115) which shows the huge percentage change that occurred in 1980. 41 . Paper Technology, Vol.34, No.10, 1993, p.10; Paper Technology, Vol.35, No.9, 1994, p.2. 42 . Paper Technology, Vol.15, No.1, 1974, pp.3 & 4. The two entities combined on 10 Jan. 1974. 43 . PIRA was formed by the merger of The Paper and Board Research Association at Kenley with the Printing and Allied Trades Research Association (PATRA) at Leatherhead – Paper Technology, Vol.10, No.5, 1969, p.366. People and equipment completed the transfer from the Kenley site to Leatherhead over a couple of years – Paper Technology, Vol.12, No.3, 1971, p.207. PIRA existed as a separate entity for a long period, changing name to PIRA International at some point. PIRA International was acquired by Ciba Geigy in March 2004, Page 14 of 15

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who maintained the name; in 2010 the American company Smithers purchased PIRA International, renaming the entity Smithers PIRA. In 2020 the PIRA name was dropped as Smithers rebranded all of their holdings under the parent name – Paper Technology International, Vol.61, No.1, 2020, p.8. 44 . Paper Technology, Vol.34, No.9, 1993, p.20. 45 . Paper Technology, Vol.35, No.7, 1994, pp.14-15. 46 . Paper Technology, Vol.36, No.8, p.23. 47 . Paper Technology, Vol.1, No.3, 1960, pp.240-241. 48 . Paper Technology, Vol.2, No.1, 1961, p.16. 49 . Paper Technology, Vol.4, No.3, 1963, pp.216-217. 50 . Paper Technology, Vol.7, No.3, 1966, p.301. 51 . Paper Technology, Vol.9, No.3, 1968, p.179. 52 . Paper Technology, Vol.11, No.3, 1970, p.160.

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PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2 2020

Products & Services PITA CORPORATE SUPPLIER MEMBERS Page 2 Page 4 Page 6 Page 8 Page 10 Page 11 Page 13 Page 14 Page 16 Page 17 Page 19

ABB ABB ABB ABB ABB ABB ABB Andritz GridBeyond Toscotec Valmet

OTHER SUPPLIERS Page 21 Ametek Page 23 Henkel Page 24 InfraTec Page 26 Signal Group Page 28 Stanley Page 29 Tsubaki

ABB & IBM bolster cybersecurity (Software) Analytics and AI Software (Software) L&W Tear Tester (Sensor) APC & wet-end control (Software) Colour measurement sensor (Sensor) Fiber recovery & pulp thickening (Sensor) Weight virtual measurement (Sensor) New belt press (Machinery) Energy Calculator (Software) Optima winders (Machinery) Update to global services offering (Maintenance)

Surface inspection system (Sensor) High temperature sealants (Maintenance) Thermographic camera (Sensor) VOC emissions analyser (Sensor) Stair climber (Health & Safety) High wear chain (Machinery)

The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members â€“ both individual and corporate â€“ dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology International and the PITA Annual Review, both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating.

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ABB AND IBM TO BOLSTER CYBERSECURITY FOR INDUSTRIAL OPERATIONS ABB and IBM announced a collaboration focused on connecting cybersecurity and operational technology (OT). As a first result of this collaboration, ABB has developed a new OT Security Event Monitoring Service that combines ABB’s process control system domain expertise with IBM’s security event monitoring portfolio to help improve security for industrial operators. Industrial control system environments are increasingly targeted in cyber-attacks. In fact, IBM’s latest X-Force Threat Intelligence Index found that attacks on industrial and manufacturing facilities have increased by over 2,000% since 2018. To better connect OT data with the broader IT security ecosystem, ABB has developed a new offering that allows security events from ABB to be sent to IBM’s security information and event management platform known as QRadar. The ABB solution was designed according to a reference architecture jointly developed by ABB and IBM. It provides the domain knowledge needed to swiftly react to security incidents related to process control, and is especially suited for complex industrial processes in industries such as oil, gas, chemicals and mining. The new event collection and forwarding software which enables this integration is currently being used by early adopter customers and will be made broadly available by ABB in the coming months. This collaboration marks the first time that OT data and process industry domain expertise is being brought directly into a Security Information and Event Monitoring (SIEM) system, allowing threats to be managed as part of an organization’s broader cybersecurity operations and strategy. “ABB’s collaboration with IBM makes it possible to analyze process control events in the context of security and impact to the operational environment, delivering strong improvement in our OT cyber threat visibility across the board,” said Robert Putman, Global Manager of Cyber Security Service for Industrial Automation at ABB. Disruption of production due to a cyberattack or technical glitches can be costly in terms of lost production and damage to physical assets. Most mature operational monitoring is focused on the performance of the asset, whether it be a gas turbine for electricity, a drive system used to crush ore, or simple monitoring of pollution output from a chemical facility. The new ABB offering allows ABB’s process control system data collection and forwarding technology to harvest event log detail from ABB process control systems, and share that information with IBM Security QRadar, which uses automation and artificial intelligence to help identify security anomalies and potential threats. "We see the integration of these solutions as bringing market-leading capabilities together for a singular view of OT security,” said Dr. Andreas Kühmichel, CTO, Chemicals, Petroleum & Industrial Products, IBM. “With more comprehensive OT and IT security visibility, clients can help reduce the risk of production being suddenly interrupted due to a security event, resulting in costly downtime and broader risk to the company.” The ABB and IBM technologies involved in this solution are designed on open platforms allowing them to operate on the edge and deploy easily across hybrid cloud environments spanning on-premise, private or public clouds. The joint solution is designed so that security Page 2 of 29

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processes operate via automation and do not disturb industrial workflows. The security analysis in QRadar operates through a use case library, which automatically flags incidents and triggers corresponding alarms. The two companies plan continued collaboration in the realm of OT security, in order to develop new capabilities and offerings that address customer challenges in this space. ABB (ABBN: SIX Swiss Ex) is a leading global engineering company that energizes the transformation of society and industry to achieve a more productive, sustainable future. By connecting software to its electrification, robotics, automation and motion portfolio, ABB pushes the boundaries of technology to drive performance to new levels. With a history of excellence stretching back more than 130 years, ABBâ€™s success is driven by 110,000 talented employees in over 100 countries. www.abb.com About IBM Security IBM Security offers one of the most advanced and integrated portfolios of enterprise security products and services. The portfolio, supported by world-renowned IBM X-ForceÂŽ research, enables organizations to effectively manage risk and defend against emerging threats. IBM operates one of the world's broadest security research, development and delivery organizations, monitors 70 billion security events per day in more than 130 countries, and has been granted more than 10,000 security patents worldwide. For more information, please check www.ibm.com/security, follow @IBMSecurity on Twitter or visit the IBM Security Intelligence blog.

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ABB’S NEW ANALYTICS AND AI SOFTWARE HELPS PRODUCERS OPTIMIZE OPERATIONS IN DEMANDING MARKET CONDITIONS The ABB Ability™ Genix Industrial Analytics and AI Suite is a scalable advanced analytics platform with pre-built, easy-to-use applications and services. It collects, contextualizes and converts operational, engineering and information technology data into actionable insights that help industries improve operations, optimize asset management and streamline business processes safely and sustainably. Analyst studies suggest that industrial companies typically are able to use only 20 percent of the data generated, which severely limits their ability to apply data analytics meaningfully. ABB’s new solution operates as a digital data convergence point where streams of information from diverse sources across the plant and enterprise are put into context through a unified analytics model. Application of artificial intelligence on this data produces meaningful insights for prediction and optimization that improve business performance. “We believe that the place to start a data analytics journey in the process, energy and hybrid industries is by building on the existing digital technology – the automation that controls the production processes,” said Peter Terwiesch, President of ABB Industrial Automation. “We see a huge opportunity for our customers to use their data from operations better, by combining it with engineering and information technology data for multi-dimensional decision making. This new approach will help our customers make literally billions of better decisions.” ABB AbilityTM Genix is composed of a data analytics platform and applications, supplemented by ABB services, that help customers decide which assets, processes and risk profiles can be improved, and assists customers in designing and applying those analytics. Featuring a library of applications, customers can subscribe to a variety of analytics on demand, as business needs dictate, speeding up the traditional process of requesting and scheduling support from suppliers. Scalable from plant to enterprise, ABB Ability™ Genix supports a variety of deployments including cloud, hybrid and on-premise. ABB Ability™ Genix leverages Microsoft Azure for integrated cloud connectivity and services through ABB’s strategic partnership with Microsoft. “The ABB Ability™ Genix Suite brings unique value by unlocking the combined power of diverse data, domain knowledge, technology and AI,” said Rajesh Ramachandran, Chief Digital Officer for ABB Industrial Automation. “ABB Ability™ Genix helps asset-intensive producers with complex processes to make timely and accurate decisions through deep analytics and optimization across the plant and enterprise. “We have designed this modular and flexible suite so that customers at different stages in their digitalization journey can adopt ABB Ability™ Genix to accelerate business outcomes while protecting existing investments.” A key component of ABB AbilityTM Genix is the ABB Ability™ Edgenius Operations Data Manager that connects, collects, and analyzes operational technology data at the point of production. ABB Ability™ Edgenius uses data generated by operational technology such as DCS and devices to produce analytics that improve production processes and asset utilization. ABB Ability™ Edgenius can be deployed on its own, or integrated with ABB AbilityTM Genix so that operational data is combined with other data for strategic business analytics.

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“There is great value in data generated by automation that controls real-time production,” said Bernhard Eschermann, Chief Technology Officer for ABB Industrial Automation. “With ABB AbilityTM Edgenius, we can pull data from these real-time control systems and make it available to predict issues and prescribe actions that help us use assets better and fine-tune production processes.” Further details can be found online: ABB Ability™ Genix ABB Ability™ Edgenius

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ABB L&W TEARING TESTER ABB has launched its market-leading L&W Tearing Tester with enhancements to ease operator use and safe handling, expand on tearing resistance testing capabilities and improve digital connectivity. Paper mills already recognize the instrument for safely and accurately measuring tearing resistance on all paper grades and its unique automation, digitalization and safety features. Tearing resistance is a crucial determinant of product toughness and machine runnability and can help mills characterize pulp to determine if refining and reinforcement fibers are optimized. ABB’s L&W Tearing Tester, which uses a pendulum to further tear a pre-cut sample, helps mills achieve tearing strength results faster with automatic clamping and notch cutting of the sample piece as well as automatic pendulum release, catch and retraction. Plus, testing for different grades is now faster than ever with interchangeable weights for the instrument’s one pendulum. Lab technicians will benefit from a user-friendly touchscreen and more ergonomic-friendly operation. They will also be better protected with the two-hand operation requirement, avoiding contact with moving parts and the blade, and a unique pendulum safety guard that minimizes the risk of injury without interrupting the pendulum swing or slowing the test. The instrument interfaces with ABB’s L&W Lab Management System, a web-based automated data acquisition and lab reporting solution that helps halve lab procedure times. With its capability to connect to ABB Ability™ Manufacturing Execution System for pulp and paper, manufacturers gain visibility of data across the mill and the entire enterprise to ensure consistent product quality. “All mills aim for the best possible product toughness and machine runnability, and yet many struggle with measurement challenges – such as reliability or repeatability – associated with ageing equipment that could affect improvement opportunities,” said Per Sandstrom, Head of Lab and Process Testing Measurements for ABB Pulp & Paper. “The new ABB L&W Tearing Tester is the only instrument on the market that combines the best modern automation, digitalization and safety advancements to deliver accurate and repeatable tearing strength results to help expedite quality and machine optimization.” As the worldwide market leader for paper testing technical support, with local service organizations in all markets, ABB provides a comprehensive support network for the L&W Tearing Tester using L&W-specific calibration devices that are regularly certified with traceable calibration from global certification institutes. For further information on ABB L&W Tearing Tester, please visit: https://new.abb.com/pulppaper/abb-in-pulp-and-paper/products/lorentzen-wettre-products/laboratory-papertesting/paper-strength-testing/l-w-tearing-tester

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ABB LAUNCHES LATEST DIGITAL SOLUTION FOR TOTAL CONTROL OVER WET END OPERATIONS TO MAXIMIZE PRODUCTIVITY AND PROFIT ABB has launched the latest generation of its Advanced Process Control (APC) to provide complete digital control over wet end operations, optimizing productivity and profit for paper mills globally. Wet End Control — an ABB Ability™ APC solution for paper mills — stabilizes the wet end process and reduces variability by controlling, monitoring and optimizing retention performance. It uses a multivariable model predictive control approach to predict future wet end process behavior, making automatic adjustments to stabilize ash levels, reduce white water consistency variability and minimize chemical and filler dosages.

ABB Wet End Control: example of multivariable model predictive control This results in improved machine runnability by helping to reduce sheet breaks, and accelerating grade changes and break recovery. Papermakers can then track performance from the wet end to the final sheet. It is available as a subscription-based service delivered via ABB Ability™ Collaborative Operations, with structured remote monitoring and expert analysis of control performance for sustainable results. In addition to its impact on productivity, Wet End Control helps to minimize raw material, chemical costs and broke usage, ultimately reducing the environmental impact and leading to lower steam consumption and increased energy savings. “We know that continuous monitoring of wet end operations is crucial to driving process improvements,” said Ramesh Satini, global product manager for Pulp & Paper Control Systems, ABB. “We developed our Wet End Control solution to address this need by automatically managing targets and implementing cost efficiencies within process constraints. By adopting this ABB service, mills will benefit from ongoing insight and collaboration to optimize stability for long-term gains and minimized operator interventions.” Wet End Control is part of a fully integrated quality measurement, control and optimization solution that works seamlessly with ABB Ability 800xA control system or a third-party Page 8 of 29

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alternative (via OPC interface). ABBâ€™s latest APC platform allows dynamic model adaption to capture varying process dynamics for tighter control, while optimally working within operational parameters to maximize the economic gain. The solution is suitable for all mills seeking a quality measurement, control and optimization solution that enables paper specifications to be met at the lowest possible cost.

ABB Wet End Control in action

Operator interface for Wet End Control, an ABB Abilityâ„˘ Advance Process Control solution

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ABB UPGRADES HIGH-PERFORMANCE COLOR MEASUREMENT SENSOR WITH COLOR PROFILES FOR CONTINUOUS MEASUREMENT AND ENHANCED PAPER QUALITY ABB has added its new Color Profiles to its popular High-Performance Color Measurement sensor, improving on its industry-leading technology and expanding papermakers’ ability to identify and resolve a range of potential production problems, including the close monitoring of coating profiles. Incorporating LED technology for superior measurements, the new Color Profiles functionality allows for easier identification of variations in color brightness, florescence, opacity and whiteness. This permits operators to take corrective action to resolve issues with size press operation, unevenly applied coatings or - for white top liner producers - coverage consistency. The sensor, purposely designed for a quick and easy upgrade path from the ABB Smart Color sensor that is now in the ‘Limited’ lifecycle phase, permits faster color and UV-color measurements to facilitate process automation and control, together with other ABB scanning sensors. In addition, the compact, modular optics design with no moving parts reduces maintenance and lifecycle costs, improves service access and can result in lower short-term variability. “The High-Performance Color Measurement sensor with Color Profiles is a great example of our commitment to continuous product development, designed to help customers improve both their productivity and profit,” said Robert Byrne, Software Development Manager, ABB Pulp & Paper. “With the new Color Profiles capability and ABB’s unparalleled color measurement and control expertise, this truly is cutting-edge technology with clear benefits for the entire papermaking industry.” Existing customers can add value to their system investment by upgrading to the new Color Profiles feature, and mills with ABB Ability™ connections can further benefit from live collaboration with ABB experts on profile data to make improvements. For further information visit: https://new.abb.com/pulp-paper

Dashboard showing the ABB High-Performance Color Measurement sensor's new Color Profiles feature Page 10 of 29

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NEW SOLUTION FOR FIBER RECOVERY AND PULP THICKENING ABB has launched Strength Virtual Measurement, an ABB Ability™ Performance Service that enables mills to predict strength properties through accurate online measurements – also known as a soft sensor – resulting in a stronger, lighter product that costs less to produce.

An operator at ABB's collaborative Operations Center in Helsinki, Finland The solution, suitable for all grades, works by leveraging machine-learning generated models to produce online strength calculations for one or more properties at a frequency needed to meet machine-specific requirements. Frequent measurements, with an accuracy that approaches lab results, help operators maintain strength properties closer to their lower limits, reducing raw material usage, increasing machine speed and enabling faster grade changes. This is delivered through ABB Collaborative Operations, a service which connects production, headquarters and ABB personnel with remote access to ABB digital technologies, data analytics and domain expertise, providing them with the right information to keep operations running. It incorporates ongoing performance monitoring, enabling optimization actions to be implemented in real time to improve the accuracy and robustness of online strength calculations. “Our new approach to soft sensors combines unrivalled proficiency in advanced analytics, a patent-pending online calculation engine with auto-correlation and ongoing performance analysis to create a virtual measurement with proven accuracy and reliability,” said John Schroeder, Global Product Manager for ABB Ability™ applications for pulp and paper. “With built in performance indices, operators can monitor process parameters, respond to alerts and rapidly adjust paper machine settings to optimize paper strength, reduce costs and increase production throughout, ultimately increasing profitability.” Strength Virtual Measurement integrates seamlessly with third-party systems and ABB offerings including ABB distributed and quality control systems, ABB L&W Autoline and other ABB Ability™ solutions, providing superior visibility for precise actions to optimize strength properties. It is the first of several new Virtual Measurement soft sensor solutions to be released during 2020 and forms part of the ABB Ability™ Performance Service for paper mills suite, focusing on maximizing equipment and process efficiency. Page 11 of 29

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Figure 1 - Lab measurements, which are performed only after a reel is produced, before Strength Virtual Measurement trials. White strip = on-spec paper

Figure 2 - Strength Virtual Measurement enables operators to create on-spec paper at less cost as adjustments are made during production For more information about the solution go to: https://new.abb.com/

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NEW ABB WEIGHT VIRTUAL MEASUREMENT REDUCES SHEET BREAK RECOVERY TIME AND BOOSTS MILL PROFITABILITY ABB launched Weight Virtual Measurement, an ABB Ability™ Performance Service that allows paper, packaging and tissue manufacturers to recover quickly from sheet breaks. It works by reducing the amount of off-spec paper produced directly after sheet breaks and during the subsequent start-up period, potentially saving thousands of dollars each year. The new digital solution uses inputs that affect product weight - such as stock flow, consistency, first pass retention and machine speed - to provide an online conditioned weight measurement during a sheet break event when the Quality Control System (QCS) weight sensor cannot provide a measurement since there is no paper to be measured. By providing operators with a continuously optimized, machine-learning generated measurement model, or ‘soft sensor’, Weight Virtual Measurement helps reduce downtime, improve grade change times and decrease the time to achieve on-spec paper. Operator displays combine various inputs and highlight when the Virtual Measurement is available in the absence of the QCS measurement. Operators can view the current status and work with a choice of adjustments to get back on target. “Our new Weight Virtual Measurement solution is unlike any other in that it combines deep industry expertise with advanced analytics, machine-learning technologies, proprietary modelling and auto-calibration techniques to create an accurate and robust virtual sensor,” said John Schroeder, Global Product Manager for ABB Ability™ applications for pulp and paper. “This will enable mills to make more strategic decisions such as balancing the cost options of getting their production up and running faster versus delaying putting the paper on the reel to avoid compromising their paper quality.” Weight Virtual Measurement joins the ABB Ability™ Performance Service suite that includes other Virtual Measurement features for pulp and paper mills, all of which do not require an ABB DCS or QCS for implementation. It is delivered via ABB Ability™ Collaborative Operations, a service delivery model that connects production, headquarters and ABB personnel with remote access to ABB digital technologies, data analytics and domain expertise, and incorporates ongoing performance monitoring and analysis of the online calculated weight. For more information about the solution go to: https://new.abb.com/pulp-paper/abb-in-pulpand-paper/service/advanced-services/performance-services-for-paper-mills/weight-virtualmeasurement

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ANDRITZ PRESENTS NEW BELT PRESS RANGE FOR THE ENVIRONMENT INDUSTRY International technology group ANDRITZ presents the SME-Q and the SMX-Q, the new belt presses for the environment industry reflecting the very latest state of the art. Due to their low-profile components, they are extremely operator-friendly and feature high quality design with low maintenance needs, thus ensuring maximum performance in terms of dryness and throughput. Different Models for a Wide Range of Requirements The medium-pressure belt filter presses in the new SME-Q range are suitable primarily for standard and medium duty performance levels, while the high-pressure belt presses in the SMX-Q series were developed for medium to heavy-duty performance levels where each individual machine must achieve high throughputs. The two machines include the same features in terms of design and have an extra-long thickening zone, a camber wedge for a steady, optimized pressure increase, a low profile, and an open, stainless steel frame structure for easy access. Both models will provide excellent operating availability and reliability in operation. Investment versus Throughput and Performance Compared to the SMX-Q, the medium-pressure belt press SME-Q provides a smaller footprint at lower investment cost and has been specifically developed for small to mediumsized sewage treatment plants and for industrial applications. The investment costs are low due to its optimized structural weight. In addition, the innovative design of the belt press makes it possible to dismantle parts of the machine quickly and easily so that it can be transported in conventional containers or on standard-size trucks. The high-pressure belt press SMX-Q delivers highest throughputs thanks to its large filtration and pressing area. Its robust frame structure generates high belt tension and high pressure on the sludge to provide the best dewatering performance for a belt press. The specific features of the SMX-Q enable this machine to be adapted to almost any application â€“ even with the most challenging dewatering requirements. Among the advantages of the new ANDRITZ belt presses are the lower investment costs (SME-Q) compared to other products currently available on the market, perfect dewatering results, highest throughputs, and lowest residual moisture. They offer the right technical solution for municipal and industrial sludge treatment plants, for thickening and dewatering in a single stage (thanks to the efficient thickening zone or combination with a gravity table) and for achieving high efficiency in specific applications such as pulp and paper, manure, biogas, slaughterhouse and chemical sludges. https://www.andritz.com/newsroom-en/separation/2020-10-07-smx-q-group

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Volume 6, Number 2, 2020

FREE TOOL TO CALCULATE VALUE OF ENERGY FLEXIBILITY IN I&C GridBeyond, the leader in intelligent energy technology, have released a free online tool – the Energy Opportunity Calculator. The tool is designed to enable industrial and commercial businesses to learn how much money they could earn and save through demand response and energy optimization services. The Energy Opportunity Calculator draws on GridBeyond’s extensive experience in the energy markets and engineering knowledge of site assets and inherent flexibility. Energy users simply enter three pieces of information: location, industry and electricity consumption (in MW, kWh, MWh or electricity spend), and the output is the financial benefits their site could gain access to. The result is split into two sections, revenues and savings, and uses the typical percentage of flexibility for the user’s industry, the typical services and programmes available to that industry, and the values of those programmes to generate the results. The revenues are based upon demand response and capacity opportunities, while the savings are based upon typical energy efficiencies, trading and price optimisation opportunities, as well as the operational efficiencies that can be attained. The user can then download a bespoke, personalized report containing further detail on their results, with additional information on the services they can participate in, the assets typically found in their industry, and an overview of their market. Michael Phelan, CEO & Co-Founder of GridBeyond, commented: “In our mission to simplify the complex energy market, the Energy Opportunity Calculator provides industrial and commercial businesses the possibility to understand their potential earnings and savings without undertaking a full audit.” “We found that, from an end user’s perspective, the visibility of a site’s value in the energy markets is often clouded. Service providers talk extensively about value per MW, but don’t necessarily have the knowledge of application to ascertain the amount of flexibility actually available within particular industries and the breadth of services both within and outside of DSR.” “This tool does not negate the need for a full audit by any stretch. We understand there are nuances and differences from site to site, however we also understand the value to our prospective clients in learning what they could earn and save. It’s a tool to start conversations within businesses based on our own benchmarking from years of working within energy management and demand response for industrial and commercial sites.” Mark Davis, Managing Director for UK & Ireland at GridBeyond, added: “There’s no denying that Covid-19 has significantly impacted industrial and commercial businesses. Bottom-lines will have taken a hit, whether due to closed production, the cost of increased safety measures, loss of sales, or otherwise.” “We consistently encourage businesses not to overlook energy as a source of backfilling some of this lost revenue, and this tool will enable energy users to truly understand the scale of the opportunities we’re talking about. We can’t guarantee returns, as the markets are continually changing, however we can use the market knowledge we have to determine a site’s worth.”

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The GridBeyond Energy Opportunity Calculator is free for all to use and can be accessed via the following link: https://gridbeyond.com/energy-opportunity-calculator/ About GridBeyond Transform energy into opportunity. GridBeyond is a global leader in intelligent energy technology for industrial, commercial, institutional and utility partners. Energy users are provided the ability to manage and control demand response participation, energy performance, markets and costs via the multi-award-winning AI Point platform. By stacking various market opportunities and programmes, GridBeyond delivers demand response revenues, enhanced savings, strengthened operations and sustainability to over 400 I&C sites worldwide, including some of the planetâ€™s best-loved brands. Furthermore, networks and utilities are empowered to optimise electricity supply and provide value-add opportunities to their customers. By connecting grid operators, operational load, distributed generation, storage, EV charging and utilities to integrated energy services, GridBeyondâ€™s vision is to build a shared energy economy that delivers sustainability, resilience, affordability and adaptability through collaboration and innovation. GridBeyond was founded in 2007 and is home to the worldâ€™s first hybrid battery and demand network. A powerful combination of technological excellence, consultative approach and unrivalled expertise means that GridBeyond partners and clients have future-proof access to energy services.

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Volume 6, Number 2, 2020

TOSCOTEC LAUNCHES NEW OPTIMA REWINDERS FOR TOP WINDING QUALITY AND EFFICIENCY Following a complete design upgrade of its rewinder line, Toscotec launched the new OPTIMA rewinders. The new line has achieved recognition in the market with eight rewinders already sold in Europe, North America and Asia, including single and double width machines. With six OPTIMA lines as part of turnkey orders by C.A.S. Paper Mill in Thailand, Paloma in Slovenia, Cartiera Confalone in Italy and Essel in Turkey, Toscotec further strengthened its position as advanced technology supplier of complete lines from the tissue machine down to the rewinder. The other two rewinders were sold to leading tissue manufacturers that remain confidential. The new OPTIMA line preserves the bulk and softness of the parent reels and boosts winding performance, thereby increasing the overall production efficiency. Securing softness and quality Through an innovative combination of center wind assist control of the parent reels, unwinding web tensioning system and rewinding nip control system, OPTIMA rewinders preserve tissue quality and deliver optimal reel uniformity. The unwinding stands feature a compensation system for out-of-round parent reels and a Center Wind Assist (CWA) control, which consists of a combination of belt driven and center drive system, which reduces the pressure applied on the paper by the belts of the unwinding stands. Compared with different systems available on the market, this system reduces the generation of dust and the installed power, which is shared between the belt and the CWA through a motor torque sharing design. OPTIMA’s efficient web tensioning system avoids elongation loss throughout the rewinder. This is achieved by continuously and precisely controlling the speed of the drive motors, also during machine acceleration and deceleration, in order to carefully guide the paper down to the rewinding station, while avoiding stretching it. The rewinding section features an automatic nip control system, operating through the load cells installed on the rider roll and the core chucks, which send continuous feedback to the control system, so that the actual thickness and bulk of the wound reel is detected and adjusted in real time. As a result, bulk loss is guaranteed to be less than 3% and the elongation loss below 2 units. Higher production efficiency OPTIMA control system delivers the highest operation accuracy by ensuring that the wound reels have the same length and density. Uniform reel density throughout the mill’s working shifts results in an increase of winding efficiency and ultimately converting efficiency. OPTIMA’s nip control system and the consequent preservation of the bulk properties of the parent reels allow for a reduction of the creping ratio set on the tissue machine, thereby avoiding slowing down the tissue machine and reducing its daily production because of excessive elongation on the rewinder. This results in an increase in the overall efficiency of the tissue line.

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The OPTIMA rewinder line can be equipped with a fully automated shaft puller, featuring compact design for easy transportation and installation in limited space, and optimal alignment between the wound reel and the puller. For further information, please contact: Marco Dalle Piagge, Sales Director, Toscotec Tissue division, marco.dallepiagge@toscotec.com

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VALMET TAKES ITS SERVICES TO THE NEXT LEVEL FOR THE BEST CUSTOMER EXPERIENCE Valmet streamlines its services to customers globally by introducing ‘Valmet’s way to serve’ concept. The aim is to provide the best customer experience in all the touch points of the customer journey. Valmet’s services are based on comprehensive services offering, lifecycle collaboration and core commitments. “Over the years we have been constantly developing our services to improve the reliability and performance of our customers’ production processes. Valmet’s unique combination of process technology, services and automation and over 200 years of industrial experience form a strong basis to help our customers to reach the wanted maintenance and operational results of their production process,” says Aki Niemi, Business Line President, Services business line, Valmet. Right combination of services for every stage in the lifecycle Valmet’s services offering is designed to match customer’s specific need, whether it’s reduced energy and raw material costs, reduced process variability, optimized quality and production or enhanced environmental performance. The services offering ranges from spare and process parts, workshop and roll services, and fabrics all the way to field services, maintenance development and outsourcing as well as process upgrades. The services are complemented with Industrial Internet solutions on-site and remotely. Depending on the need, the service solution can be provided as a one-time delivery or as a longer-term partnership through service agreements. The key driver in Valmet’s way to serve is the lifecycle collaboration between the customer and Valmet. “When planning the investment, together with the customer we can set the foundation for optimized operational results for the production process to come. Services can help to accelerate the start-up curve when ramping up the production. By working together in maintenance and operations, we can ensure maximized reliability and optimized performance of the production process,” Niemi says. Safety comes first in all operations Valmet’s four core commitments to customers are: ‘Safety comes first,’ ‘Close to you,’ ‘Solutions to your needs’ and ‘People you can trust’. “Safety is put before anything else in our daily operations. We support customers in reaching their safety targets. Our professionals work close to customers, through a network of over 100 service centers. Our experts are also available remotely with the help of Industrial Internet and remote technologies. We work closely with our customers to find exactly the right solution to their needs. We know that trust has to be earned, and we work hard to reach that goal every day”, concludes Niemi.

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Valmet streamlines the way it serves customers globally by introducing ‘Valmet’s way to serve’. For further information, please contact: Aki Niemi, Business Line President, Services business line, Valmet, tel. +358 40 515 1145 Read more: https://www.valmet.com/campaign/valmets-way-to-serve

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SMARTADVISOR® UPGRADE PROVIDES NEW BENEFITS FOR MONITORING CONTINUOUS PROCESSES AMETEK Surface Vision, a leading provider of online surface inspection solutions, has upgraded its SmartAdvisor® web and process monitoring system, providing additional benefits for customers. Versatile and easy to use, SmartAdvisor is a video monitoring solution that helps maximize machine efficiency and yield rates. It provides high-speed, high-definition video monitoring, and process analysis to the paper, board, and tissue industries. Camera synchronization technology delivers real-time root cause analysis of defects and process interruption. This is supported by simultaneous video capture and review that provides multiple hours of footage for troubleshooting. Key benefits of the SmartAdvisor system include: • Increased line efficiency and yield • Accurate image synchronization • Multiple views across the process line • Seamless integration with the SmartView web inspection system Additionally, SmartAdvisor’s customizable system configuration can be applied in a flexible, scalable way to fit individual production requirements, delivering the most capable and costeffective solution for each user. Volker Kölmel, Global Manager Plastic, Nonwovens and Paper at AMETEK Surface Vision comments, “Designed for today’s hands-on troubleshooter, SmartAdvisor delivers proven and significant benefits from the moment it’s installed. Using perfectly synchronized high-speed cameras, strategically placed along the paper machine, SmartAdvisor accurately syncs video frames from each camera to generate a complete overview that helps identify the root cause of web defects and breaks.” The latest version of SmartAdvisor has a new user interface that improves ease of use and supports Windows 10 and Windows 7 for installation on mill networks. The upgrade also increases storage capacity for video review, allowing more than three days of image storage all at full resolution and framerate. Higher-definition cameras and multi-light control further improve image quality and the capability to identify the root cause of web breaks. Installation costs are lowered by the introduction of a fiber-optic backbone for the cameras, which offers higher system reliability and performance. This further facilitates the modification of camera locations if required. AMETEK Surface Vision’s process experts will help customers select the best web and process video monitoring solution for their individual process, with modular hardware and advanced technical support. Find out more about the SmartAdvisor solution at www.ameteksurfacevision.com.

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About AMETEK Surface Vision AMETEK Surface Vision is a world leader in automated online surface inspection solutions with a broad product portfolio optimized for web and surface inspection and monitoring and process surveillance applications. Its product portfolio includes two distinct product lines: SmartViewÂŽ systems and SmartAdvisorÂŽ systems. Each product line uniquely enables customers to inspect the surfaces of materials processed in a continuous fashion across the metals, paper, plastics, nonwovens and glass industries. Learn more by visiting ameteksurfacevision.com.

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ULTRA HIGH TEMPERATURE SEALANTS Specifically formulated for use in high temperature and high-pressure environments, LOCTITE® NS 5540 and 5550 are sealing compounds that cure in the presence of heat to form a mechanical seal on metal-to-metal flanges and fittings. They are designed to allow for disassembly during routine maintenance and can also be used as a gasket dressing to extend the service life of traditional gaskets. LOCTITE NS 5540 is a single component, high strength, product whose low viscosity makes it easily brushable onto flanges or threads. It is suitable for sealing flanges up to 20MPa (2900 psi). For higher pressure requirements, up to 34.5MPa (5000 psi), LOCTITE NS 5550 is recommended. This product is a thermal reactive, heavy bodied, fibrous paste that fills large gaps by expanding upon cure. Both products have a service temperature rating of 30°C to 700°C. These new additions are unaffected by thermal cycling and provide an immediate, lowpressure seal before curing to create a high-pressure, temperature and chemical resistant seal. They are suitable for sealing steam, hydrocarbons, gases and other process fluids typically found in power generation facilities, pulp and paper mills, mines and oil & gas refineries. Likely applications for LOCTITE NS 5540 are sealing threaded fittings, pump and turbine case flanges, doors, boiler sight glasses and for repairing leaking gaskets. As well as sealing case flanges, LOCTITE NS 5540 is the best choice for duct flanges, exhaust systems, pipe connections and pressure vessels. To see how both products are applied go to: https://10122-forms.de/downloads/AG_WE/LOCTITE_NS_5540_5550/LoctiteExtremeTemp_HowTo-HD1280x720.mp4 For more information go to: www.henkel-adhesives.co.uk

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Volume 6, Number 2, 2020

HIGH-SPEED THERMOGRAPHY IN FULL RESOLUTION WITH OVER 1,000 HZ InfraTec's camera series ImageIR® stands for infrared cameras with cooled focal-plane array photon detectors, which meet the highest demands on geometric, thermal and temporal resolution and at the same time offer excellent measurement accuracy. The ImageIR® 8300 hs extends this series with a new generation of high-speed infrared cameras. Combining the image format of (640 × 512) IR pixels with the exceptionally high frame rate of 1,004 Hz sets new standards. It allows thermographic images of excellent quality, even of extremely fast moving objects or highly dynamic thermal processes. Thus, exactly the moment that matters is captured with absolute precision, displayed with high resolution and precisely measured thermally. Due to the latest detector technology, this camera – sensitive in the mid-infrared – allows high-speed thermography in full frame format and achieves an impressively high thermal resolution of 20 mK. The radiometric image data are transferred with loss-free intelligent realtime compression - without having to use internal memory – directly via an industrial 10 GigE interface to a standard notebook for storage, control and analysis. The digital high-speed data acquisition is carried out with InfraTec's IRBIS® 3 thermography software family offering the user extensive possibilities for data analysis and documentation. The camera's wide temperature measurement range allows fast processes with large temperature gradients, such as those occurring in explosions, electrical discharges or laser machining processes, to be easily recorded. The new ImageIR® 8300 hs can be equipped with a fast rotating filter wheel to adapt the camera sensitivity to the spectral properties of the target. Equipped with up to six spectral filters, the filter wheel allows sequential measurements of high image frequency in different spectral ranges. Use of the latest detector technology The newly developed high-end thermography system from InfraTec is based on an innovative detector: T2SLS with HOT long-life technology. A complex semiconductor quantum structure forms the basis for this system, whose electro-optical properties are optimised exactly to the desired requirements. It offers an excellent signal-to-noise ratio starting at relatively high operating temperatures of about 130 K resulting in lower wear and tear on the cooling system. Thus, this thermographic camera requires significantly lower cooling capacity than conventional models, which typically operate at 77 K. This results in less stress on the integrated Stirling cooler, which in turn increases the lifetime of the camera compared to other cooled cameras. Another special feature of the ImageIR® 8300 hs is the relatively large area of the individual detector elements, which are arranged in a grid (pixel pitch) of 25 μm. The sensitivity of the detector is therefore particularly high, which means that short integration times and high frame rates can also be used for measurement objects with low temperatures. Flexible usage of the camera due to modular design As for all models of the ImageIR® series, the ImageIR® 8300 hs offers a wide range of high quality interchangeable full optics optimised for the respective focal length and spectral application. All standard full optics can be combined with an optional motorised focus unit, which can be precisely remote controlled using the camera software and allows fast motorised focusing. Thus, the ImageIR® 8300 hs fits seamlessly into the modular camera series ImageIR®. It is equipped with a lens, detector and interface module. It can be individually configured to customer requirements and tailored to the most demanding applications in science and industry. Users also benefit from additional software and hardware functions that can be added at any time and are thus prepared for changing Page 24 of 29

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requirements in the future. Superior and simultaneously robust design, selected materials and a manufacturing process that meets the highest quality standards ensure the best reliability, long service life and thus an excellent protection of your investment. InfraTec GmbH Infrarotsensorik und Messtechnik The InfraTec infrared sensor and measuring technology company was founded in 1991 and has its headquarters in Dresden, Germany. The privately held company employs more than 200 employees and has its own design, manufacturing and distribution capabilities. Infrared sensors, with electrically tuneable filters based on MOEMS, count among the products of the infrared sensor division, next to spectrally mono and multi-channel infrared detectors. These detectors can be used in gas analysis, fire and flame sensor technology and spectroscopy. With its Infrared Measurement business unit, InfraTec is one of the leading suppliers of commercial thermal imaging technology. In addition to the high-end camera series ImageIRÂŽ and the VarioCAMÂŽ High Definition series, InfraTec offers turnkey thermographic automation solutions.

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TRANSPORTABLE VOC EMISSIONS ANALYSER SUBMITTED FOR QAL1 CERTIFICATION As a British developer and manufacturer of gas analysers, Signal Group follows the emergence of international Standards very closely. This is because Standards ensure that monitors are fit for purpose, and also because regulators require operators to employ suitably certified equipment. Signal Group is therefore delighted to confirm that the latest version of its portable FID analyser, the 3010 MINIFID PURE is being submitted to TÜV for QAL1 testing. This is a procedure to demonstrate that the instrument is suitable for its intended purpose, and meets required performance standards and the uncertainty allowances specified in EU Directives. Previous versions of this instrument were certified in the UK according to the MCERTS requirements. However, performance requirements have since been unified in Europe, and at the same time product development work has enhanced the capabilities of this product line, so the time has come for us to seek certification to the latest Standards. Which Standards apply to the discontinuous measurement of TOC emissions? There are two European standards that apply to the use of portable FID analysers. BS EN 15267-4:2017 specifies the performance levels and test procedures for automated measuring systems used for discontinuous (periodic) measurements of stationary source emissions. It applies to testing based on techniques specified by a standard reference method (SRM) or an alternative method. BS EN 12619:2013 specifies the flame ionisation detector (FID) method, and is intended for use as a SRM for the measurement of the mass concentration of gaseous and vaporous organic substances in stationary source emissions up to 1,000 mg/m³. This Standard specifies the requirements for a FID instrument with results expressed in mg/m³ as total carbon (TVOC). Why monitor the emissions of organic compounds? A wide variety of industrial processes produce emissions that contain organic carbon. For example, volatile organic carbon compounds (VOCs) are a common constituent in the emissions of processes that involve petrochemicals, paints, coatings, adhesives and cleaning chemicals. In many of these processes, solvents play a major role and the release of VOCs represents a risk to health and the environment. Similarly, combustion processes give rise to VOC emissions, particularly where combustion involves the use of an organic fuel. This includes fossil fuels such as petrol, diesel and oil, as well as wastes and biofuels. Organic carbon can exist in emissions as a gas or a vapour; the latter being characterised as a substance that is a mixture of two phases - gaseous and liquid. By monitoring total organic carbon (TOC) concentration in emissions, process operators can demonstrate compliance with relevant legislation, as well as provide insights for process optimisation, because the presence of organic compounds is an indicator of incomplete combustion. In addition, it is common practice to monitor TOC in order to measure the effectiveness of abatement processes. Transportable Continuous Emission Monitoring Systems (T-CEMs) are generally employed for regulatory monitoring; verifying and calibrating installed CEMs, according to the requirements of BS EN 14181, and for providing temporary back-up when permanent CEMs are not operating. Page 26 of 29

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PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

How to monitor TOC emissions As a Standard Reference Method, TOC measurement with a FID is generally preferred. However, where there is a potential for the emission of particularly toxic VOCs, the site permit may include a requirement for the monitoring of individual organic compounds, which means that a monitoring technology capable of speciation will be necessary. Alternatively, it may be necessary for the monitoring activity to distinguish between methane and nonmethane VOCs. Where speciation is required, technology such as Gas Chromatography, FTIR or Mass Spectrometry may be necessary. However, if speciation is required, a continuous emissions monitoring system (CEMS) will almost always be necessary. Choosing the right instrument If monitoring is being undertaken for compliance purposes, the environmental permit will indicate the certification required for the emissions monitoring equipment. This will limit the number of suitable suppliers, but a number of other issues will need to be addressed when choosing the most appropriate instrument. If a transportable instrument is required: is it suitably robust? and has it been designed for portability? Keep in mind that it may be necessary to transport the equipment from site to site, and to carry the instrument up ladders in potentially inclement weather. Price is of course a major consideration, but it is best to compare lifetime costs that take operational costs into account as well as the purchase price. So, issues such as calibration and service requirements will need to be addressed. It is also advisable to examine the supplier’s reputation – do they have support capability? do they have longstanding experience in the supply of portable FIDs? and what has been the experience of previous users? With over 40 years of experience in the development and manufacture of FIDs, Signal Group can claim to score very highly in such comparisons with the well proven and competitively priced Model 3010 MiniFid. Once this transportable FID has passed through the QAL1 process, Signal’s SOLAR Series IV permanently installed FID will also be submitted for certification. The prospect of the latest FID technology with TÜV certification for QAL 1 of EN 14181 will be of major interest to stack testers and process operators with a requirement to monitor TOC emissions. www.signal-group.com

Page 27 of 29

Products & Services

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

LATEST TECHNICAL DEVELOPMENT FROM STANLEY - MOVE 425KG ON THE STAIRS Stanleyâ€™s latest development in stair climber technology is the Sprinter Pro 425, which enables a single operator to move loads on the stairs that weigh up to an incredible 425kg. The technical advancements of the Sprinter Pro 425 allow weighty items to be carried up and down the stairs confidently and safely by remote control. The automatic self-levelling stair climber protects the user and the load by automatically adapting to the incline of the stairs, even if the steps are uneven or the staircase is narrow. Stanley solving your manual handling problems Stringent health and safety regulations mean that businesses must ensure that their employees are protected at work. Manoeuvring heavy items can be dangerous and often requires several people to do so. Not only does this pose a health and safety risk, but the transported goods can become damaged in the process. Other challenges such as a steep, narrow, and tight staircase contribute to the hazardous problem. As does uneven flooring and unknown terrain. Stanley has listened to these challenges to develop the Sprinter Pro 425 which resolves the many high-risk issues associated with moving heavy items on the stairs. The Sprinter Pro 425â€™s intuitive remote control removes the requirement to manually manage a heavy load, reducing operator fatigue. Further peace of mind is given as the automatic self-levelling function will always adapt to the loads centre of gravity. Each item is therefore kept balanced during transportation. An operator can also safely and confidently stop anywhere on the stairs. Fears over the dropping of materials or causing an injury are now eliminated. Such features protect the load, particularly important when moving sensitive or high-value items such as telecoms equipment, data servers, or electrical motors as an example. The high-grade anti-slip caterpillar tracks are non-marking making the machine suitable for use both indoor and outdoor, as well as on flat surfaces. Concerns over narrow staircases or tight landings are no longer since the Sprinter Pro 425 can move in the tightest of spaces with 360-degree rotation. All of which reduces the risk of injury to ultimately enhance the safety measures within your business. Stanley is offering a FREE demonstration of the Sprinter Pro 425 stair climber at your business. To book your demo or to request a product specification sheet simply email: sales@stanleyhandling.co.uk

Page 28 of 29

Products & Services

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

TITAN CHAIN OFFERS SIGNIFICANT IMPROVEMENTS IN WEAR LIFE FOR ULTRA DEMANDING APPLICATIONS Tsubaki’s latest innovation, TSUBAKI Titan Chain, is designed to offer previously unobtainable wear life in harsh applications, like in abrasive and dusty conditions, such as those found in timber mills, stone sawyers or brickworks. Created by the company’s global research & development team in Japan, TSUBAKI Titan Chain combines the best features of the existing premium GT4 Winner chain with new specifications designed to deliver the ultimate in wear performance. Perhaps the most obvious feature of TSUBAKI Titan chain is the use of seamless bushes that incorporate Lube Grooves. The bushes are precision made and perfectly cylindrical, to ensure the smoothest possible operation which in itself will help minimise wear. Enhancing this, the special Lube Grooves ensure oil is retained at the very point of contact - where the chain needs it most. This limits the wear between pin and bush, significantly improving the wear life as a result. The pins have a special coating that provides an extra hard yet low friction surface, thus helping increase wear life further. As a result of these innovations, maintenance cost and downtime are reduced to a minimum. These factors, plus the reduced frequency of swapping out old chain for new, add up to a significant reduction in the Total Cost of Ownership. The development team have specified corrosion resistant nickel plated outer link plates for the TSUBAKI Titan Chain, which combined with black oxide inner link plates provide an extra layer of protection against corrosion. Tsubaki has also incorporated its unique process of Ring Coining the connecting links, which ensures that the chain can be specified up to its full load capacity. As standard, TSUBAKI Titan Chain is available in sizes 12B to 32B. Additional sizes, multistrand and attachment options will be available upon request. TSUBAKI Titan Chain was developed in Japan at the company’s Kyotanabe Technical Centre with input from Tsubakimoto Europe B.V. It is seen as part of the Tsubaki Group’s commitment to conserve the environment and reduce the impact of its products and operations by helping customers reduce energy consumption and save cost.

Page 29 of 29

Products & Services

PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 6, Number 2, 2020

Installations The following pages contain a summary of the various installations and orders from around the world of papermaking, wood panel and saw mills, and bio-power generation, received between the start of May 2020 and end of November 2020.

Page 1 of 8

Installations

PAPERmaking! g

FROM THE PUBLISHERS OF PAP PER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

Aktül Kağıt Turkey ANON (via Andritz) ANON (Middle East, Angel Project) ANON (paper & cardboard plant Finland) ANON (cartonboard mill, Germany) ANON (Tissue Mills, France) ANON (Western Europe and Africa) ‘a leading tissue manufacturer’ ANON (various locations to confidential global producer) AO Knauf Petroboard Kommunar Russia APP Gold Hongye Paper plant Nantong Province of Jiangsu China Arctic Paper Kostrzyn Mill Poland Asia Symbol (Guangdong) Paper XinHui China Asia Symbol (Shandong) Pulp and Paper Co., Ltd China AustroCel Hallein GmbH Hallein Austria Aviretta Ettringen Mill Bavaria Germany BillerudKorsnäs Gruvön Mill Sweden

URL

A.Celli

rewinder

Clyde Industries

Pasaban

sootblowers for new recovery and power boilers at pulp mill complete tissue plant including automation sheeter

Pasaban

sheeter

PMP

New rewinder

Toscotec

Two tissue machine rebuilds

Toscotec

Andritz

Rebuild of two drying sections, and the wet-end and winding section of a third rebuild of reel-up (KM2)

AO-Andritz

A.Celli

Three tissue rewinders

APP-ACelli

PMP

Rebuild of press section (PM2)

ArcticPaperPMP

Valmet

a fine paper line with stock preparation and extensive automation

AsiaSymbolValmet

Valmet

Recovery boiler optimizer APC

Asia-Valmet

Valmet

Automation for bioethanol plant

Hallein-Valmet

Toscotec

rebuild PM4 dryer section

AvirettaToscotec

Andritz

Washer, MC pump and standpipe for brown stock wash system

Bill-Andritz

Overmade

Page 2 of 8

ORDER DESCRIPTION

Installations

AktulKagitACelli Anon-Clyde AnonMEOvermade PasabanFinland PasabanGermany AnonFrancePMP AnonVariousToscotec

PAPERmaking! g

FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

ORDER DESCRIPTION

URL

Bracell “STAR” Project Pulp Mill Lençóis Paulista State of São Paulo Brazil Cartiera di Ferrara Italy Cartiera di Ferrara Italy Cartiera Fornaci Italy Cartiera San Martino Broccostella-Frosinone Italy Cartiera San Martino Broccostella-Frosinone Italy Cartones Y Papeles Del Risaralda Risaralda Mill Western Colombia USA Chelny Paper Mill Tatarstan Russia Daio Paper Corporation Kawanoe Zoki Shikokuchuo Island Japan Domtar Kingsport Mill Tennessee USA DS Smith Kemsley Mill UK DS Smith Lucca Mill Italy ECOFARIO GmbH Germany

Andritz

incineration plant for noncondensable gases

Bracell-Andritz

Sael

Rebuild of wet end, shoe press and driers

Ferrara-Sael

Toscotec

Dryer section rebuild

Sael

water cooled sectional drive

FerraraToscotec Cartiera-Sael

Sael

DCS control management (subcontractor to ST Macchine)

Cart San Martino

ST Macchine

stock preparation system

Cart San Martino

Toscotec

a steel Yankee to replace a cast iron Yankee (PM1)

CartonesToscotec

Projet BV

dry end radial saw tail cutters

Chelny-Projet

Valmet

tissue production line

Daio-Valmet

Voith

Recycled stock preparation system including water, sludge and reject handling

Domtar-Voith

Runtech

three turbo blowers for PM3

Smith-Runtech

GE Gas Power

gas turbine

DSSmithGEPower

Valmet

ECOFARIOValmet

Egypt Kuwait Holding Sadat City Egypt

Dieffenbacher

automation to wastewater treatment plant to remove microplastics in an industrial pilot plant complete MDF plant with continuous press

Page 3 of 8

Installations

EgyptDieffenbacher

PAPERmaking! g

FROM THE PUBLISHERS OF PAP PER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

ORDER DESCRIPTION

URL

Gold Hongye Paper Nantong Province of Jiangsu China Göteborg Energi AB Gothenburg Sweden Grupo Gondi Monterrey Mill Mexico

A.Celli

Three rewinders

Gold-ACelli

Valmet

Biomass boiler plant for district hot water system

GoteborgValmet

ABB

GrupoGondiABB

Guangdong Hengan Paper Co., Ltd. (Hengan Group) Yunfu Guangdong China Guangxi Sun Paper Co. Ltd. Beihai Guangxi China Guangxi Xiangsheng Household Materials Technology Co., Ltd. China Hayat Kimya Mersin Turkey Hayat Kimya Moscow Russia Heinzel Group Laakirchen Mill Germany Highland Pellets LLC Arkansas USA Hitachi Zosen Inova AG Moscow Russia H.P. Papéis Volta Grande MG Brazil Iggesund Mill, Sweden

Andritz

electrical package and drives automation, and automated testing system (containerboard, PM7) four tissue machines

Andritz

chemi-thermomechanical pulping system, and two tissue machines for its new mill

Guangxi-Andritz

Siempelkamp

particleboard production line

GuangxiSiempelkamp

Valmet

To supply a seventh tissue line (to HK) including automation package To supply eight tissue line (to HK) including automation package Digital transformation of site (Industry 4.0)

Hayat-Valmet

Büttner

Four drum driers (for pellet producer)

HighlandButtner

Valmet

automation to a new waste-toenergy facility

Hitachi-Valmet

Hergen

Two tissue machines

HPPapeisHergen

Tasowheel

Iggesund-taso

IHSAN Pakistan

A.Celli

Refurbish of two-headbox slice control Doctor rewinder (cotton spunlace nonwoven)

Valmet

Voith

Page 4 of 8

Installations

GuangdongAndritz

Hayat-Valmet2

Heinzel-Voith

IHSAN-Acelli

PAPERmaking! g

FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

ORDER DESCRIPTION

URL

ITC Limited India Jingxing Paper Malaysia Kartogroup España S.L. Burriana Mill Spain Kastamonu Entegre Samsun Turkey Klabin Ortigueira Mill Brazil Klabin Puma II project Brazil Kookil Paper (Zhangjiagang) Limited Corporation Jiangsu Province China Kumar Group India LD Celulose S.A. Triângulo Mineiro region Brazil LD Celulose S.A. Minas Gerais state Brazil LD Celulose S.A. Minas Gerais state Brazil Lucart Porcari Mill Italy Metsä Board Kemi Mill Finland Metsä Board Kyro Board Mill Finland Metsä Fibre Kemi Bioproduct Mill Finland

Valmet

machine vision system (BM7)

ITC-Valmet

Voith

Two OCC stock preparation systems with automation Steel Yankee and air and electrical systems for PM2, and dust removal for PM2 and PM4 forming and press line (particleboard)

Jingxing-Voith

complete biomass gasification plant and a new biomass handling line (PUMA Project II) six Total Solids Measurement analysers for the waste and water treatment plants complete stock preparation system including broke handling and fibre recovery

Klabin-Andritz

Siempelkamp

feasibility study for project

Kumar-Siemp

Babcock & Wilson

cooling towers for a pulp mill

LDCelluloseB&W

Clyde Industries

boiler cleaning equipment

LDCelluloseClyde

Valmet

ash treatment system

LDCell-Valmet

Baker Hughes

12.5MW gas turbine

Lucart-Baker Hughes

Valmet

Industrial Internet solutions to enhance quality and productivity

Metsa B-Valmet

Raumaster

roll handling system

MetsaRaumaster

ABB

Metsa-ABB

Metsä Fibre Kemi Bioproduct Mill Finland

AFRY

electrification and drive technology (bioproduct mill). Also, engineering, project management and site services of the chlorine dioxide plant. engineering, project management and site services of the chlorine dioxide plant

Andritz

Siempelkamp

Andritz

Valmet

Andritz

Page 5 of 8

Installations

KartogroupAndritz KastamonuSieplelkamp

Klabin-Valmet

Kookil-Andritz

Metsa F-AFRY

PAPERmaking! g

FROM THE PUBLISHERS OF PAP PER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

ORDER DESCRIPTION

URL

automation for recycled containerboard machine (PM3); also a conversion rebuild of PM3 (recycled containerboard to high quality coater containerboard) paper machine and winder machine drive systems, Quality Control System, and Open Control System for rebuild of PM3. Also, L&W Autoline for automated paper testing. upgrade drives and integrate quality control

Modern KartonValmet

Valmet

Steam boiler plant to utilise refuse-derived fuels (RDF)

Norsk-Valmet

Valmet

Off-machine coater (PC4)

Oji-Valmet

Valmet

automation system extension and solids measurements dataPARC™ data historian, analytics, and visualization software sensors and instrumentation

Oulu-Valmet

Sprinkler system, alarm system and fire protection equipment

Palm-Calanbau

Palm-Heimbach

Waterstromen

supply forming fabrics, press felts, shoe press belts and transfer belts for the new PM5 water treatment plant

Pasaban

sheeters on BM2 and BM3

PKV-Pasaban

Hergen

Refurbishment of PM1 reel with automatic reel spool feeder

Penha-Hergen

Dieffenbacher

Retrofit of steam preheater (MDF plant)

PfliedererDieffenbacher

Minerals Technologies

to re-establish a 35,000tpy satellite PCC plant

PhoenixMinerals

Modern Karton Sanayii Ve Ticaret Tekirdağ Mill Turkey

Valmet

New-Indy Containerboard South Carolina USA

ABB

Nordic Kraft pulp mill Lebel-Sur-Quevillion northern Quebec Canada Norske Skog Bruck an der Mur Paper Mill Austria Oji Papéis Especiais Piracicaba Brazil Oulu Waterworks Finland Palm Group (All Europe)

ABB

Palm Group Aalen-Neukochen Mill Germany Palm Group Aalen-Neukochen Mill Germany Palm Group Aalen-Neukochen Mill Germany Papierfabriek Doetinchem Doetinchem Netherlands Papier- und Kartonfabrik Varel Varel Germany Penha Coronel Vivida Prefecture Brazil Pfleiderer’s Baruth Brandenburg Germany Phoenix Paper LLC Wickliffe Paper Mill Kentuck

BTG

Calanbau Brandschutzanlagen GmbH Heimbach

Page 6 of 8

Installations

New-Indy-ABB

Nordic-ABB

Palm-BTG

Palm-BTG2

PFDWaterstromem

PAPERmaking! g

FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

PT. Cikarang Listrindo Tbk Indonesia PT. Tanjungenim Lestari Pulp and Paper Indonesia Sappi Europe Gratkorn Pulp & Paper Mill Austria Segezha Group Segezha Republic of Karelia Russia Shanying Paper Guangdong Zhaoqing Mill China Shandong Sun Holdings Group Beihai plant province of Guangxi China Smurfit Kappa Uberaba Mill Brazil Södra Cell Mörrum Mill Sweden Södra Cell Mörrum Mill Sweden Södra Värö Mill Sweden Södra Värö Mill Sweden

Valmet

Stora Enso Forshaga Mill Sweden Stora Enso Oulu Mill Finland Stora Enso Oulu Mill Finland Stora Enso Oulu Mill Finland

ORDER DESCRIPTION biomass fuel feeding system (green energy power station) Pulp production upgrade technology

PT Cik-Valmet

Sumitomo Shi FW

modernise an existing circulating fluidized bed (CFB) boiler

SappiSumitomo

Andritz

stock preparation equipment for sack paper production (350bdmt/d)

SegezhaAndritz

Valmet

container board making line with extensive automation

ShanyingValmet

A.Celli

three tissue rewinders

Sun-ACelli

PMP

two hydraulic headboxes

Smurfit-PMP

Cellwood

Grubbens horizontal pulper (TM2)

Sodra-Cellwood

ABB

QCS system

Sodra-ABB

FITNIR

online pulp liquor analyzer

Sodra-Fitnir

Ledinek

CLT production line (Cross Laminated Timber)

Sodra-Ledinek

UMV Coating Systems

offline coater for application of dispersion barriers

Procemex

Web monitoring and web inspection systems (BM7 conversion) profiling control (CD control) automation technology

Oulu-Procemex

clothing including forming fabrics, press felts, shoe press belts and dryer fabrics for startup

Oulu-Valmet

Valmet

Tasowheel

Valmet

Page 7 of 8

URL

Installations

PT TEL-Valmet

Stora-Taso

PAPERmaking! g

FROM THE PUBLISHERS OF PAP PER TECHNOLOGY Volume 6, Number 2, 2020

COMPANY, SITE

SUPPLIER

Sun Paper Beihai Mill China Sun Paper Beihai Mill China Sun Paper Beihai Mill China Toyo Engineering Corporation Ichihara Chiba Prefecture Japan Tuas Nexus Singapore ULK Group LLC Pinega Sawmill Plant Russia UPM-Kymmene Corporation Paso de los Toros Fray Bentos Uruguay Vinda Personal Care (Guangdong) Co., Ltd. Yangjiang Guangdong China Viridor Dunbar East Lothian Scotland Viridor (6 sites, UK) Waggeryd Cell AB Vaggeryd Pulp Mill Sweden WEPA Bridgend Mill UK WEPA Piechowice Mill Poland Xuong Giang Paper Mill Vietnam

Andritz

URL

Pulp dewatering and white liquor plant technologies and key process equipment boiler cleaning equipment

Sun-Andritz

Cooking and fibreline (capacity 800,000tpy of bleached hardwood kraft) and BCTMP line circulating fluidized bed biomas boiler with a flue gas cleaning system (75 MWe)

Sun-Valmet

four flue gas treatment systems (Water Reclamation Plant) lumber handling lines

Tuas-NexusAndritz ULK-Jartek

Kemira

extension of bleaching chemicals contract

UPM-Kemira

Andritz

stock preparation system to feed four tissue machines

Vinda-Andritz

Valmet

automation to a gas clean-up system (landfill site)

Viridor-Valmet

Valmet

automation service agreement (energy-from-waste plants) software system (warehouse management module)

Viridor-Valmet

Valmet

tissue line including full automation

WEPA-Valmet

Toscotec

tissue line

WEPAToscotec

Andritz

Tissue machine (54tpd) with stock preparation

Xuong-Andritz

Clyde Industries

Valmet

Andritz

Andritz Jartek Invest

AFRY

Page 8 of 8

ORDER DESCRIPTION

Installations

Sun-Clyde

Toyo-Andritz

WaggerydAFRY

PAPERmaking! O THE PUBLISHERS U S S OF O PAPER TECHNOLOGY INTERNATIONAL FROM

Volume 6, Number 2, 2020

Research Articles Most journals and magazines devoted to the paper industry contain a mixture of news, features and some technical articles. Very few contain research items, and even fewer of these are peer-reviewed. This listing contains the most recent articles from five of the remaining specialist English language journals that publish original peer-reviewed research: x x x x x

APPITA JOURNAL – nothing new in 2020 IPPITA JOURNAL – nothing new in 2020 JOURNAL OF KOREA TAPPI NORDIC PULP & PAPER RESEARCH JOURNAL TAPPI JOURNAL

Notes: 1. In 2019 APPITA JOURNAL separated from the APPITA MAGAZINE and is now only available as an electronic publication; it is still protected by a paywall. 2. IPPTA JOURNAL is available online free of charge around 6-9 months after publication. It does not appear to have been published since June 2019. 3. The excellent J-FOR+ from Canada appears to have ceased publication in late 2018. 4. JOURNAL OF KOREA TAPPI is still published and is available open-access 5. NORDIC PULP & PAPER RESEARCH JOURNAL remains available only behind a paywall, and is still published. 6. TAPPI JOURNAL went open-access in 2020. 7. JAPAN TAPPI JOURNAL is another excellent journal, but the full papers are only reproduced in Japanese with a short abstract in English, so are not included.

Page 1 of 6

Research Articles

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

JOURNAL OF KOREA TAPPI, Vol.52(1), February 2020 1. Exploration of Deep Eutectic Solvents for the Extraction of Lignocellulosic Materials 2. A Comparative Analysis of the Characteristics of Cellulose Nanofibril Films Fabricated by Batch-Wise Mode 3. Isolation and Characterization of Lignin Using Coagulant Treatment in Black Liquid 4. Effect of Pulp Volume Concentration in Fibrillation of Organosolv Pulp by Kneading Process 5. Sound Absorption Coefficient and Sound Transmission Loss of Porous Sponge Attached Corrugated Cardboard of Noise Insulation Cover 6. Cationization of Pulp Fibers as Pretreatment and Preparation of Cationic Cellulose Nanofibrils 7. Effects of Gas Grafting Treatment with Different Amounts of Palmitoyl Chloride on Properties of CNF-Coated Paper 8. Effects of Wet Pressing Temperature, Filler Addition, and PAE-Based Strength Agents on Initial Wet-Web Strength of HwBKP-SwBKP Sheet 9. Characteristics of Coating Binder and Quality Improvement of Coated Paper (I) : Effect of the Particle Size of VAE Emulsion Binders 10. Characteristics of Coating Binder and Quality Improvement of Coated Paper (II) : Effect of the Glass Transition Temperature of VAE Emulsion Binders 11. Glycol Ether-Organosolv Pulping Process of Radiata Pine and Comparison of Characteristics with UKP 12. Fuel Characteristics of Wood Pellets Fabricated with Tropical Acacia Wood 13. Effects of Refining Degree, Pulp Mixing Ratio, and PAE-Based Strength Agents on Initial Wet-Web Strength of HwBKP-SwBKP Sheet JOURNAL OF KOREA TAPPI, Vol.52(2), April 2020 1. Identification and Detection of Surface Defects of Outer Package Printed Matter Based on Machine Vision 2. Impact of Monovalent Cations on the Rheology of Cellulose Nanofibrils 3. Mathematical Modeling of Drying Kinetics for Pulp Sheet Based on Fickâ€™s Second Law of Diffusion 4. Refining Mechanism of Combined Refining Plates with Different Bar Angles 5. Web Inspection Algorithm for Low Contrast Paper Defects Based on Artificial Bee Colony Optimization 6. Effect of Successive Processing on Properties of Ligno-Cellulosic Micro-Fines from Pinus densiflora with Microwave Irradiation 7. Thermodynamic Analysis on Heat Recovery System of Hermetic Gas Hood for Paper Machine 8. The Effects of Mild Alkaline Pretreatment on the Enzymatic Hydrolysis of Eucalyptus pellita Wood 9. Impact of Divalent Cations on the Rheology of Cellulose Nanofibrils 10. No-Load Power of Disc Refiner in Low Consistency Refining JOURNAL OF KOREA TAPPI, Vol.52(3), June 2020 1. Development of Printing Paper Containing Calcium Carbonate-Attached Wood Flours 2. Research on Modeling and Dynamic Characteristics Analysis of Alkali Recovery Furnace 3. Analysis of Energy Savings in Packing Paper Mill with EGAER Tool 4. A Study on the Manufacture of Archival Envelopes for Cultural Properties Using the Korean Traditional Paper Hydrophobized with Gas Grafting Treatment Page 2 of 6

Research Articles

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

5. Comparison of Fibrillation Characteristics of Unbleached Kraft Pulp and Organosolv Pulp by Alkali Kneading Process 6. Manufacturing Functional Pulp Mold with Citrus Pomace 7. Study of Water Absorption Properties of Water Absorption Core Made of Pulp Mold 8. Heat Transfer Characteristics in Horizontal Rectangular Channel of Multi-Channel Cylinder Dryer 9. Fundamental Study on Barrier Coating of Paper Using Cationic Cellulose Nanofibrils 10. Evaluation of Characteristics of Kraft Pulp Made from Rice Husks 11. Effect of Electron-Beam Irradiation on White Water Generated in Paper Mills 12. Fundamental Study of the Production of Paper Ash Made from Paper Sludge I : Evaluation of the Characteristics of Paper Ash Made from Paper Sludge in a Specialty Paper Mill 13. Changes in Properties of 3D Printing Filaments by Extruding at Different Temperatures and Lignin Contents JOURNAL OF KOREA TAPPI, Vol.52(4), August 2020 1. Study on the Gas Grafting Efficiency of Paper According to Carbon Number of Fatty Acid Chloride 2. Forecasting the Import Price of Hardwood Bleached Kraft Pulp Using a Time-Series Model 3. Numerical Simulation of Condensation Heat Transfer and Structural Optimization in Dryer of Paper Machine 4. An Algorithm for On-Line Image Segmentation of Multiple Paper Defects Based on Fast Two-Dimensional Threshold Method 5. Sequential Modeling of Paper Drying Process to Reduce Thermal Energy Use, Part 1: Theoretical Model 6. Effective Use of Binder Composition in Functional Coating (I): Flow Characteristics of Coating Dispersion and Properties of Coated Paper 7. Dissolution of Lignin-Rich Organosolv Pulps by PEG and Urea Contents in Aqueous Alkaline Solution 8. Increased of Cooking Efficiency of the Lye Cooking Method for Traditional Korean Papermaking 9. Changes in Properties of Pulp Mold Depending on the Forming Conditions of Wet Pulp Mold Manufacturing 10. The Change in the Properties of Seeding Pad by the Fallen Leaves JOURNAL OF KOREA TAPPI, Vol.52(5), October 2020 1. Impact of Electrolytes on the Rheology of TEMPO-oxidized Cellulose Nanofibril 2. Research on Fuzzy Fractional Order PID Control of Liquid Temperature in Displacement Digester 3. Modeling on Thermal Efficiency and Nox Emission of Alkali Recovery Furnace Depending on Oxygen Content of Flue Gas 4. Accuracy of the Different Calculation Methods of Specific Edge Load 5. Effect of GCC-MFC Composite Application as Fillers on Fold Crack of Coated Paper NORDIC PULP & PAPER RESEARCH JOURNAL, Vol.35 No.2, June 2020 1. Bleaching: Unbleached and bleached handsheet characteristics of Subabul heartwood and sapwood Page 3 of 6

Research Articles

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

2. Mechanical pulping: Material characterisation for natural fibres: compressibility, permeability and friction 3. Paper Technology: Affecting the bonding between PLA fibrils and kraft pulp for improving paper dry-strength 4. Paper Technology: High strength paper from high yield pulps by means of hotpressing 5. Paper Technology: On the development of a continuous methodology to fractionate microfibriallated cellulose 6. Paper Technology: Non-wood fibers as raw material for pulp and paper industry 7. Paper Physics: Modeling of tensile index using uncertain data sets 8. Paper Physics: The shear and compressive yield stress of fibrillated acacia pulp fiber suspensions 9. Paper Chemistry: Composite filler by pre-flocculation of fiber fines and PCC and its effect on paper properties 10. Paper Chemistry: Sodium dodecyl sulphate (SDS) residue analysis of foam-formed cellulose-based products 11. Printing: Determining the quality of paper substrates containing triticale pulp for printing industry 12. Nanotechnology: Preparation of CaCO3 nanoparticle/pulp fiber composites using ultrafine bubbles 13. Miscellaneous: Anatomical, morphological and chemical characteristics of kaun straw (Seetaria-ltalika) 14. Miscellaneous: The influence of process parameters of screen-printed invasive plant paper electrodes on cyclic voltammetry NORDIC PULP & PAPER RESEARCH JOURNAL, Vol.35 No.3, September 2020 1. Chemical Pulping: Feasibility of removal Sâˆ’2 from Kraft black liquor recovery cycle with synthetic adsorbents (Cu-PAC and Cu-GAC) 2. Chemical pulping: Effect of bark content in mixed hardwood chips on pulp and papermaking properties 3. Chemical Pulping: Process modifications to obtain a prehydrolysis kraft dissolving pulp with low limiting pulp viscosity 4. Bleaching: Synthesis of chlorine dioxide stable solution by combined reduction and its decomposition kinetics 5. Paper Physics: Elastic-plastic model for the mechanical properties of paperboard as a function of moisture 6. Paper Physics: Evaluating the use of a tactile sensor for measuring carton compliance 7. Paper Chemistry: Determination of hydrophobic degree of paper packaging materials by a tracer-assisted headspace gas chromatography 8. Paper Chemistry: Jet-cooked papermaking starches studied using 1H NMRrelaxometry and viscometry 9. Paper Chemistry: Enhanced separation of cellulose from bamboo with a combined process of steam explosion pretreatment and alkaline-oxidative cooking 10. Paper Chemistry: Improving mechanical properties of recycled paper via surface spraying carboxymethyl starch-grafted-polyacrylamide 11. Coating: The influence of coating composition on the structural and functional properties of coated paper for packaging applications 12. Coating: Coating factors influencing the fold cracking of coated papers 13. Coating: The effect of zeolite on inkjet coated paper surface properties and deinking Page 4 of 6

Research Articles

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

14. Printing: Exploitation influence on compressible polyurethane flexographic sleeve properties 15. Environmental Impact: Effects of pH shock on microaerobic activated sludge system with a graphene oxide/nano-magnetic powder composite 16. Environmental Impact: Experimental study on filtering papermaking black liquor by dynamic blade crossflow membrane 17. Environmental Impact: Partial circuit closure of filtrate in an ECF bleaching plant 18. Nanotechnology: Paperboard as a substrate for biocompatible slippery liquidinfused porous surfaces TAPPI JOURNAL, May 2020 1. Editorial: TAPPI Journal 2019 Best Research Paper runner-up focuses on persistent issue of cracking at the fold in coated papers, 2. Effects of a PFI refiner’s operational parameters on the swellability of recycled fiber 3. Fundamental understanding of removal of liquid thin film trapped between fibers in the paper drying process: A microscopic approach 4. Alternative “green” lime kiln fuels: Part I—Pulping/recovery byproducts 5. Alternative “green” lime kiln fuels: Part II—Woody biomass, bio-oils, gasification, and hydrogen TAPPI JOURNAL, June 2020 1. Editorial: Fifty years with TAPPI: A personal and professional perspective 2. Cationic emulsions of maleic anhydride derivatives of oleic and abietic acid for hydrophobic sizing of paper 3. Development of a fast brightness testing method for mechanical pulp based on microwave oven drying 4. Integrated study of flue gas flow and superheating process in a recovery boiler using computational fluid dynamics and 1D-process modeling 5. Case study: Paper mill power plant optimization—balancing steam venting with mill demand TAPPI JOURNAL, July 2020 1. Editorial: Vamsi Jasti: New nonwovens expert joins TAPPI Journal editorial board 2. Equilibrium moisture content in wet pressing of paper 3. Combatting lime kiln ringing problems at the Arauco Constitución mill 4. Viscoelastic web curl due to storage in wound rolls 5. Wet pressing and product quality: Review of previous pilot machine trials TAPPI JOURNAL, August 2020 1. Editorial: Risks and rewards of research during a pandemic 2. Mill experience of calcium carbonate scale formation in green liquor pipelines 3. Modeling of the energy of a smelt-water explosion in the recovery boiler dissolving tank 4. On-machine visible dirt measurement on moving sheets and the relationships to standard laboratory methods 5. Relating bending stiffness measurements across various free span lengths

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Research Articles

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

TAPPI JOURNAL, September 2020 1. Editorial: Explore the experience of this yearâ€™s virtual PEERS Conference 2. Soybean peroxidase treatment of ultra-high kappa softwood pulp to enhance yield and physical properties 3. Lignin carbohydrate complex studies during kraft pulping for producing paper grade pulp from birch 4. Repulping of wet strength paper towel with potassium monopersulfate 5. Quantification of vegetable oil in recycled paper TAPPI JOURNAL, October 2020 1. Guest Editorial: Nonwovens industry responds to COVID-19 challenge, 2. Improving paper wet strength via increased lignin content and hot-pressing temperature 3. Investigation of the influencing factors in odor emission from wet-end white water 4. Characterization of chia plant (Salvia hispanica) for pulping 5. Crossflow filtration of green liquor for increased pulp production, improved green liquor quality, and energy savings

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Research Articles

PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 6, Number 2 2020

Technical Abstracts The general peer-reviewed scientific and engineering press consists of several thousand journals, conference proceedings and books published annually. In among the multitude of articles, presentations and chapters is a small but select number of items that relate to papermaking, environmental and waste processing, packaging, moulded pulp and wood panel manufacture. The abstracts contained in this report show the most recently published items likely to prove of interest to our readership, arranged as follows:

Page 2

Biorefinery Coating

Page 3

Environment

Page 4

Moulded Pulp

Page 6

Nano-Science Packaging Technology

Page 8

Papermaking

Page 9

Pulp Testing

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Tissue

Page 11

Waste Treatment

Page 14

Wood Panel

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

BIOREFINERY Alternative initiatives for nonǦwood chemical pulping and integration with the biorefinery concept: A review, M. Sarwar Jahan, M. Mostafizur Rahman & N. Yonghao, Biofpr, https://doi.org/10.1002/bbb.2143. Conventional pulping processes, such as soda, sodaǦAntraquinone (AQ), and kraft, are currently used for nonǦwood pulping. The main challenges of nonǦwood pulping in conventional pulping processes are (1) large amounts of silica cause silicaǦrelated operational difficulties in the process; (2) large amounts of fines/parenchyma cells decrease the drainage; and (3) the bulky nature of raw materials increases the collection/transportation cost, hampering largeǦscale commercial operations. Alternative pulping processes are therefore being developed. This paper reviews the current status of alternative nonǦwood pulping processes and their integration with the biorefinery concept. Several promising methods have been investigated at the laboratory or pilot scale. Organic acid and potassium hydroxide pulping processes are attractive alternatives for nonǦwood pulping. Dissolved lignin and hemicelluloses in spent liquor can lead to the production of valuable coǦproducts, fitting well with the integrated biorefinery concept. NonǦwood biomass can be important raw material for pulping in forestǦdeficient countries. Lignocellulosic Fibers from Renewable Resources Using Green Chemistry for a Circular Economy, Khandoker S. Salem, Ved Naithani, Hasan Jameel, Lucian Lucia & Lokendra Pal, Global Challenges, https://doi.org/10.1002/gch2.202000065. The sustainable development of lignocellulose fibers exhibits significant potential to supplant synthetic polymer feedstocks and offers a global platform for generating sustainable packaging, bioplastics, sanitary towels, wipes, and related products. The current research explores the dynamics of fiber production from wood, nonǦwood, and agroǦresidues using carbonate hydrolysis and a mild kraft process without bleaching agents. With respect to carbonate hydrolysis, high yield, and good coarseness fibers are attained using a simple, lowǦcost, and ecofriendly process. Fibers produced using a mild kraft process have lower Klason lignin, carboxyl content, surface charges, and higher fiber length, and crystallinity. Eucalyptus fibers show the highest crystallinity while softwood carbonate fibers show the lowest crystallinity. Hemp hurd fibers contain the highest concentration of hardǦtoǦremove water, and thus, suffer maximum flattening visualized by the microscopic images. The relatively high yield sustainable fibers with versatile properties can provide a significant economic benefit since fiber is the dominant cost for producing various bioproducts. COATING Regenerative Superhydrophobic Paper Coatings by In Situ Formation of Waxy Nanostructures, Cynthia Cordt, Andreas Geissler & Markus Biesalski, Advanced Materials Interfaces, https://doi.org/10.1002/admi.202001265. This scientific−technical approach describes a unique selfǦstructuring coating material made of wax and polysaccharide derivatives, which results in extremely waterǦrepellent properties if applied to solid surfaces. When cooling the coating down from the molten state, the material forms a nanostructured superhydrophobic surface within seconds. This possibility of a fast thermally induced regeneration of nanoscale surface textures creates the potential to restore superhydrophobic coating properties even after mechanical damage caused, among others, by longǦterm use and complex processing and machining steps. Therefore, this coating material has great potential for engineering applications such as superhydrophobic wettability of paper surfaces. Depending on a particular application, there are different requirements for the interaction of paper with water. The highest possible water resistance, which is achieved by superhydrophobic properties, is a quality Page 2 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

feature for a majority of paper products, such as packaging materials or novel construction materials, since the ingress of moisture is a major cause of paper damage. Cellulose micro and nanofibrils as coating agent for improved printability in office papers, Ana F. Lourenço, José A.F. Gamelas, Pedro Sarmento & Paulo J.T. Ferreira, Cellulose, 27, 2020, https://doi.org/10.1007/s10570-020-03184-9. The use of nanocelluloses is being conducted for the most diverse applications. Their performance as coating agent has been mainly explored to improve barrier properties, as they emerge as perfect candidate for plastic substitution, but it is also important to explore their potential to improve printing quality. In the present work, the influence of different nanocelluloses, obtained through mechanical, enzymatic, TEMPO-mediated oxidation and carboxymethylation treatments, in the coating process and inkjet printability of office papers was assessed. The results revealed that the cellulose nanofibrils are better for printability than the microfibrils. But the size and charge of the former must be taken into account, since fibrils of very small size penetrate the paper structure, dragging the pigments from the surface, and very anionic nanofibrils can also have negative influence on the optical density. Besides, an interesting synergy between surface-sizing starch and the cellulose nanofibrils was found to occur as the latter closed the paper structure, which prevented starch from penetrating, while potentiating both of their positive effects on ink pigment entrapment. An additional study of characterization of inkjet pigments was also performed. Surface modification of clayǦcoated paper by atmosphericǦpressure plasma in air, Vlasta Štěpánová, Dušan Kováčik, Miroslav Zemánek, Monika Stupavská, Zlata Kelar Tučeková & Mirko Černák, Surface and Interface Analysis, 42(12), Dec. 2020, https://doi.org/10.1002/sia.6798. The aim of this work was the wettability improvement of clayǦcoated paper by ambient air plasma exposure. Industrial corona with a volume dielectric barrier discharge in cylindrical configuration was used as a plasma source; the exposure times varied from 0.25 up to 5 s. Water contact angle (WCA) measurement and surface free energy (SFE) evaluation were carried out for the estimation of wettability changes. Plasma treatment in the duration of 0.25 s was sufficient to decrease the WCA almost to the half of the original value, which was 76°. SFE of paper has increased by 40%–50% after plasma treatment. LongǦterm ageing effect study of treated samples was carried out up to 3 months after the treatment. WCA did not reach the original value even after 3 months, and it was still 20%–30% lower. O/C ratio increased from 0.7 to 1.8 in case of 5Ǧs plasma treatment, and the new chemical bonds (C=O, O–C=O) were created on the surface. ENVIRONMENT The future of single-use paper coffee cups: Current progress and outlook, N. Triantafillopoulos & A.A. Koukoulas, BioResources, 15(3), DOI: 10.15376/biores.15.3.Triantafillopoulos. The expanded use of environmentally friendly and sustainable foodservice packaging continues to be a prime focus of stakeholders across the foodservice value chain. Paper-based coffee cups is one product segment where effective recycling of waste cups remains elusive. As a result, material substitutes for polyethylene liners are emerging to solve the problem of waste cups. In this paper, current and emerging commercial material technologies used in the production of paperbased coffee cups that are readily recyclable with other paper grades are reviewed. Many of these material solutions are also compostable. Special attention is paid to the rapidly evolving, alternative large-scale production of bioplastics. Multiple efforts to effectively develop a more environmentally friendly paper cup are also examined. It is clear that Page 3 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

broad adoption of proposed solutions will require an integrated commitment and approach to circular economics. Specifically, this includes: changes in consumer behavior; brand owner initiatives to meet sustainability goals; governmental policies that limit or forbid use of fossil-based cups; and easily accessible infrastructures at the consumer level for the collection, separation, and processing of biodegradable cups. Analyzing the environmental sustainability of packaging for household appliances: A test case, Daniele Landi, Paolo Cicconi & Michele Germani, Procedia CIRP, 90, 2020, https://doi.org/10.1016/j.procir.2020.01.106. Nowadays, packaging represents around 35% of the total municipal solid waste yearly generated. This paper aims at analyzing a methodology to support the redesign of a sustainable packaging for the household appliances. The approach considers the environmental impacts related to geometrical parameters and materials. In particular, here the test case is focused on the packaging for kitchen hoods. Through the proposed method, based on the use of virtual prototyping tools, an eco-design approach has been identified to analyze the main environmental impacts. A packaging redesign has been performed to reduce waste and increase the use of the components from the perspective of the circular economy. This study has been performed in accordance with the international standards ISO 14040/14044, by using a Life Cycle Assessment (LCA) from Cradle to Gate. The integration with a CAD tool has been considered to redefine the packaging shape, materials, and internal composition, keeping the same standard requirements (performance, security, etc.). LCA software SimaPro 8.5 has been used to carry out the life cycle assessment, and ReCiPe method has been chosen for the life cycle impact assessment (LCIA). A comparison has been proposed between a traditional packaging for household appliances and a new solution which integrates an interior part in molded pulp. The results show the possibility to cut down the environmental impacts of approximately 15% by a redesign with a molded pulp interior and avoiding EPS structures. MOULDED PULP Development of cellulose-based toys with moulded fibre production method, SarÄąkaya, E., and Demirel, H., BioResources. 15(3), DOI: 10.15376/biores.15.3.69026911. In this work, a toy was developed from bleached sulphate pulp via a moulded fibre production technique. Moulded fibre products are generally used to preserve main products from damage during transportation and stow them in a particular order. This work investigated the use of moulded fibre products in daily life as final products. Bleached softwood sulphate pulp was used for the experiments to avoid the potential hygiene problems of using recycled paper for toy production. The physical properties of different degrees of refined sulphate pulp were evaluated during toy sample production. The results indicated that toys produced with bleached softwood sulphate pulp had optimum compression strength (22 kpgf) at the 35 SRÂ° freeness level. Produced prototypes satisfied EN 71-3:2013+A1(2014) in terms of migration element limits. Short communication on the role of cellulosic fiber-based packaging in reduction of climate change impacts, Urs Schenker, Julia Chardot, Karim Missoum, Alexey Vishtal & Julien Bras, Carbohydrate Polymers, 2020, https://doi.org/10.1016/j.carbpol.2020.117248. This short communication describes the climate change impacts of using cellulose, and more precisely cellulosic fiber-based materials, in food packaging, representing current and emerging industrial state of the art technology, without specific reference to current scientific advances. First, the different types of cellulosic fiber-based packaging materials, which can be used to replace fossilbased packaging materials, are presented for flexible and rigid applications. The focus is Page 4 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

on technological solutions with packaging properties that enable the protection of commonly sold food products. The manufacturing processes associated with these cellulosic fiber-based materials is described and the environmental impact assessment of 4 selected case studies presented: stand-up pouches, flexible flow wraps, frozen or chilled food trays, and molded pulp lids. A simplified eco-design Life Cycle Assessment (LCA) was then performed to compare each solution with its fossil-based counterpart. Differences and similarities between the various cellulosic solutions have been identified. Furthermore, the assessment confirms that cellulosic fiber-based materials have reduced environmental impacts as compared to fossil-based counterparts, if a similar packaging weight is obtained. Indeed, all impacts of plastics are between 3 and 5 kg CO2eq/kg, while all impacts of cellulosic fiber-based materials are below 1.5 kg CO2eq/kg. Improving agricultural waste pulps via self-blending concept with potential use in moulded pulp packaging, Phattharasaya Rattanawongkun, Noppadon Kerddonfag, Nattaya Tawichai, Uraiwan Intatha & Nattakan Soykeabkaew, Chemical Engineering, 8(5), https://doi.org/10.1016/j.jece.2020.104320. Agricultural wastes have been considered as an alternative sustainable resource for pulp production. In this work, banana stem (B), pineapple leaf (P) and rice straw (R) were used as raw materials for pulp extraction. The obtained pulps were moulded into sheets and their mechanical properties were evaluated. The sheets prepared from P and R pulps showed promising performance for moulded pulp packaging use. Having high cellulose content, slenderness ratio, and flexibility, these pulps were superior with a high degree of fibre bonds. Conversely, sheets prepared from B pulp had sub-standard properties. To improve the properties of B pulp, it was blended with either P or R pulp. Both tensile strength and Young’s modulus of the blended B/P and B/R sheets were improved significantly, around 63–167 % and 55–117 %, respectively. SEM images revealed that the long and flexible P and R fibres were wellentangled with the B fibres, confirming a strong network of the blended pulp sheets. A positive deviation from the linear additivity of the blended sheet’s strength was also observed. Mixing 30 % of P or R pulp with B upgraded both blended sheets to the acceptable range, showing a tensile index of approximately 44–45 Nm/g. These results indicated that pulp blending was highly efficient for enhancing properties of sub-standard pulp. Furthermore, this could possibly enable the use of all agricultural wastes as alternative raw materials for pulp and paper industries. Mold design and fabrication for production of thermoformed paper-based packaging products, Prateek Saxena, Giuliano Bissacco, Kenneth Ælkær Meinert & Filip Jakub Bedka, Journal of Manufacturing Processes, 58, 2020, https://doi.org/10.1016/j.jmapro.2020.07.029. Paper-based packaging products are a cheap and sustainable alternative to their plastic counterparts. The manufacturing process of paper molding is a relatively newer concept, and the tooling aspect remains somewhat unknown. The work done in this paper establishes a tool design approach for the molding of paper products. These products are also sometime referred to as the molded paper products (MPP). Functional requirements are identified and translated to process chains. The concept of non-deterministic and deterministic tooling is introduced. Tooling process chains based on micro-metal additive manufacturing are defined and implemented. The process chain is utilized to manufacture micro features of size 300 μm in a high aspect ratio. A comparative study on validation of tooling process chains is also discussed, and the suitability of rapid tooling over sintered tools is highlighted in this work.

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

NANOSCIENCE Lignocellulosic nanofibers for the reinforcement of brown line paper in industrial water systems, Quim Tarrés, María Cristina Area, María Evangelina Vallejos, Nanci Vanesa Ehman, Marc Delgado-Aguilar & Pere Mutjé, Cellulose, Apr. 2020, DOI: 10.1007/s10570-020-03133-6. The addition of nanofibrillated cellulose in paper production requires attention to its dispersion and retention during the paper forming process, and this is commonly facilitated by the use of retention agents. The performance of retention agents, which commonly have a cationic charge, is affected by the presence of dissolved and colloidal substances in the process water. In the process of paper production at an industrial level, especially when using recycled paper, there are a large amount of dissolved and colloidal substances in the water. A high proportion of these substances are negatively charged and are commonly referred to as anionic trash. Its presence increases the conductivity and charge density of the water, and this has a negative influence on the retention of cellulose nanofibers. In brown line paper production, some fibers have already been refined in at least one previous papermaking cycle. In this sense, recycled fibers have a reduced capacity to benefit from refining as they have suffered morphological damage. On the other hand, the addition of lignocellulosic nanofibers in the production of brown line paper has been found helpful to improve its properties and extend its lifespan. In this work the influence on the retention of nanofibers of different anionic trash levels in the water has been evaluated. The results showed its viability as a reinforcing agent in waters with high anionic trash content, through the addition of an anionic trash catching system. Nanocellulose: its applications, consequences and challenges in papermaking, Atanu Kumar Das, Md. Nazrul Islam, Md Ashaduzzaman & Mousa M. Nazhad, Journal of Packaging Technology and Research, Aug. 2020, DOI: 10.1007/s41783020-00097-7. This paper has aimed to bring out the state-of-the-art information about nanocellulose, its application in papermaking process, effect on paper properties and challenges. In papermaking process, nanocellulose is used as bionanofiller and bionanocoating material. The main objective of considering nanocellulose as a bionanofiller is to retain the strength properties after using inorganic filler, such as, GCC (ground calcium carbonate) and PCC (precipitate calcium carbonate); nanocellulose also helps to increase the filler content in paper sheet without loss of paper strength. That’s why, the application of nanocellulose as filler and coating material can solve the issues of using inorganic filler in papermaking industry. Though the production of nanocellulose needs higher energy, which increases the production cost in papermaking process, it can be minimized using different advanced technologies, such as, chemical and enzymatic pretreatment. Additionally, the incorporation of nanocellulose in recycled and virgin fiber increases some physical and strength properties of the paper. Furthermore, the increment of filler content in paper sheet due to incorporating nanocellulose can also reduce the amount of fiber in papermaking process, and it reduces the cost of fiber, which can mitigate the drawback of paper production cost because of adding nanocellulose partially. Therefore, nanocellulose has the potential to use for making value added paper and paper products to compensate the production cost. PACKAGING TECHNOLOGY Experimental Study on Moisture-Proof Coating for Corrugated Boards and Boxes, Chenyang Liu, Lijiang Huo, Yu Zhao & Yin Shang, Advanced Graphic Communication, Printing and Packaging Technology, https://doi.org/10.1007/978981-15-1864-5_57. Moisture-proof coating on the surface of corrugated boards and corrugated board box is one of effective methods to satisfy a requirement of logistics Page 6 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

distribution in damp environment. Moisture-proof coating mechanism of the corrugated board and related moisture-proof coating experimental study were discussed and carried out in this paper. Four-layer corrugated board (250 g/170 g/100 g/250 g, double C) and five-layer corrugated board (200 g/120 g/120 g/120 g/200 g, BA) were selected as experimental materials. The physical and mechanical properties of these two kinds of corrugated boards coated by damp-resistant material under different environment conditions were tested and analyzed. The optimum coating amount was determined under the conditions of temperature and humidity selected in the experiments. The results show that the combination performance of the corrugated boards and corrugated board box reached the best when the damp-resistant material consumption is 6 g/m2 under RH65%. Evaluation of measures to mitigate mineral oil migration from recycled paper in food packaging, Harrie Buist, Toon van Harmelen, Claudia van den Berg, Winfried Leeman, Marie Meima & Lisette Krul, Packaging Technology and Science, 33(12), Dec. 2020, https://doi.org/10.1002/pts.2534. The presence of mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH) in food is a safety concern. Migration to food from recycled paper and board is a relevant source of MOSH and MOAH, and the potential of several technologies to reduce it was explored. These technologies were assessed for food safety (people), environment (planet) and economy (profit) in an integrated way, using a framework developed to compare the effect of the technologies with the current state of the art. Two mature technologies were evaluated (MB12 and flotation), two in development (supercritical CO2 and thermal treatment), and two as a concept (anionic trash catchers and functionalized clays). The use of mineralǦoilǦ free inks for printing newspapers was also evaluated. It was concluded that, although it is desirable to apply mineralǦoilǦfree inks, in the shortǦterm reduction technologies have more impact. All technologies of which the effectiveness could be investigated (MB12, flotation, supercritical CO2 and thermal treatment) are able to reduce the potential migration of mineral oils by >70%, but none score optimally on all indicators. The MB12 technology shows the best overall performance and is ready for implementation, provided its patent will be available to more parties. Supercritical CO2 performs best on food safety, but environmental and economic performance has to be improved. The developed assessment framework yields a clear overview of the advantages and disadvantages of the technologies. Based on the assessment, recommendations are made to stakeholders, including the recycling industry, the ink and printing industry, the food industry and research institutes. The effect of pallet top deck stiffness on the compression strength of asymmetrically supported corrugated boxes, Chandler Quesenberry, Laszlo Horvath, John Bouldin & Marshall S. White, Packaging Technology and Science, 33(12), Dec. 2020, https://doi.org/10.1002/pts.2533. During unitized shipment, the components of unit loads are interacting with each other. During floor stacking of unit loads, the load on the top of the pallet causes the top deck of the pallet to bend, which creates an uneven top deck surface resulting in uneven or asymmetrical support of the corrugated boxes. This asymmetrical support could significantly affect the strength of the corrugated boxes, and it depends on the top deck stiffness of the pallet. This study is aimed at investigating how the variations of pallet top deck stiffness and the resulting asymmetric support affect corrugated box compression strength. The study used a scaledǦ down unit load compression test on quarterǦscale pallet designs with different deckboard thicknesses using four different corrugated box designs. Pallet top deck stiffness was determined to have a significant effect on box compression strength. There was a 27%– 37% increase in box compression strength for boxes supported by highǦstiffness pallets in Page 7 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

comparison with lowǦstiffness pallets. The fact that boxes were weaker on lowǦstiffness pallets could be explained by the uneven pressure distribution between the pallet deck and bottom layer of boxes. Pressure data showed that a higher percentage of total pressure was located under the box sidewalls that were supported on the outside stringers of lowǦ stiffness pallets in comparison with highǦstiffness pallets. This was disproportionately loading one side of the box. Utilizing the effects of pallet top deck stiffness on box compression performance, a unit load cost analysis is presented showing that a stiffer pallet can be used to carry boxes with less board material; hence, it can reduce the total unit load packaging cost. Effect of Corrugated Board Structure on Mechanical Properties, Włodzimierz Szewczyk & Maria Bieńkowska, Wood Research, 65(4), 2020, doi:/10.37763/wr.13364561/65.4.653662. The article shows the method for prediction of corrugated board properties based on automatic generation of a database containing material compositions of all the boards possible to be produced by a given manufacturer. With their large number it is not possible to carry out on the basis of measurements made on earlier manufactured products. As a result of the tests carried out with the use of data provided by the corrugated board manufacturer, it was found that using his paper materials and machinery it was possible to more than double increase the bending stiffness and edge crush resistance indexes of produced board. In some cases, the options for improving the indexes are slightly smaller, e.g. bending stiffness in the cross direction of three-layer board with flute C, the mentioned manufacturer can increase by approx. 40% of the maximum value obtained so far. PAPERMAKING Using Digital Image Processing to Characterize Flocculation of Papermaking Wastewater, Ming Li, Kaitang Hu & Jin Wang, Advances in Intelligent Systems and Computing book series (AISC, volume 1130), https://doi.org/10.1007/978-3-03039442-4_56. Wastewater generated from pulp and paper mills is a major pollution source. It is important to identity the flocculation characteristics of papermaking wastewater so that the wastewater treatment can be optimized. In this paper the characteristics of flocculation of deinking wastewater were studied by computer image processing. Experiments were carried out to acquire images of flocculation. A series of graph parameters related to floc sedimentation characteristics and time-variable parameters were found. Using computer visualization technology to study the static and dynamic behavior of wastewater flocs has many advantages; computer visualization technology can be used to improve wastewater treatment. Penetration control of surface sizing starch using cationic PAM and its effect on the bending stiffness of paper, Seo, M., Youn, H., and Lee, H., BioResources, 15(3), DOI: 10.15376/biores.15.3.5489-5502. Surface sizing is employed to increase the wetting resistance against liquids and to improve strength and surface properties of paper. Starch solution is the most widely used for surface sizing, and its effect is highly dependent upon how deep the starch solution penetrates into the paper structure. Better tensile strength can be obtained when starch penetrates deep into the thickness direction of paper. However, holdout of starch solution is beneficial for improving the stiffness and air or liquid resistance. This study was focused on the use of cationic polyacrylamide (PAM) as a surface sizing additive to control the penetration of starch solutions into paper, thus improving bending stiffness of paper. The effects of the ionic property, viscosity, and charge density of PAM on starch penetration and bending stiffness of surface sized papers were investigated. The penetration of starch solution was investigated with confocal laser Page 8 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

scanning microscopy. The enthalpy changes accompanying the mixing of cationic PAMs with oxidized starch was determined using an isothermal titration calorimeter to see the molecular level interaction between PAM and starch in mixing. The addition of cationic PAM to oxidized starch solution made starch molecules stay on the paper surface rather than penetrating into the paper structure. Influence of fiber composition and drying conditions on the bending stiffness of paper, Ham, C.-H., Youn, H.J., & Lee, H.L., BioResources, 15(4), DOI: 10.15376/biores.15.4.9197-9211. Changes in thickness, elastic modulus, and bending stiffness were studied for handsheets prepared using different fiber compositions and dried under restraint or unrestraint conditions, when exposed to various humidity conditions. Four sets of experimental studies were carried out to investigate the effect of (1) different amounts of fines (or long fibers), (2) two-ply sheet forming, (3) high temperature restraint press drying, and (4) the use of recycled fibers on the thickness, elastic modulus, and bending stiffness. The results showed that thickness, elastic modulus, and bending stiffness changed depending upon the fiber composition, single or multi-ply forming, drying conditions, and recycling of fibers. Thickness change, restraint drying, and fiber hornification during recycling were the principal factors affecting the bending stiffness in cyclic humidity conditions. PULP Modelling of dewatering wood pulp in a screw press using statistical and multivariate analysis, El Idrissi, B., Loranger, Ă‰., Lanouette, R., Bousquet, J.P., and Martinez, M., BioResources, 15(3), DOI: 10.15376/biores.15.3.5899-5912. Statistical modeling of a screw press was established by using an experimental design based on the screw rotational speed, the pulp feed consistency, the pulp feed suspension freeness, the inlet pressure, and the counter-pressure at the discharge end. The statistical models showed that the screw press outputs for each pulp could be predicted. When including all data in a global model to predict the outputs of the press for any pulp, a global statistical model was found not to be efficient by using just the five fixed parameters. The solution to this problem was to use a multivariate analysis to include more parameters, mainly about the fiber characteristics (crowding factor, fiber length, fiber width, and fines content). By including these fiber properties, the differences between each pulp were more properly analyzed. The multivariate analysis predicted the press outsets very well in a global model by using eight parameters instead of five. The R2 values of the multivariate prediction model were all higher than 0.70 and had the goodness of prediction (Q 2) higher than 0.60. TESTING Research review on devices and methods for rapid measurement of paper ash, Hu, L., Lu, X., & Ma, J., BioResources, 15(1), 2096-2110, DOI: 10.15376/biores.15.1.20962110. The Chinese national standard for paper ash measurement cannot meet the requirements for accurate and rapid ash measurement in actual production and scientific research because of the long measuring time, tedious procedures, and large human error. This paper reviews some worldwide devices and methods for rapid measurement of paper ash, including ceramic fiber muffle furnace, microwave muffle furnace, the addition of ash adjuvant, dry samples method, direct combustion of paper samples, oxygen-enriched combustion method, chemical analysis method, and ray method, etc. The differences and relationships are identified among these devices and methods. By comparing the different ash measurement methods, the rapid ash analyzer based on X-ray technology has the obvious advantages of short measuring time and small error. Lastly, the present situation and the development potential of these devices and methods are discussed in this review. Page 9 of 15

Technical Abstracts

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

Instrumentation for Measuring the Wet Frictional Property of Sanitary Pads, Ka-Po Maggie Tang, Ching-Hei Li & Chi-Wai Kan, Fibers and Polymers, 21, 2020, https://doi.org/10.1007/s12221-020-9623-3. Women wear sanitary pad for whole day during their menstruation period. They have direct skin contact with it even for sleeping and exercising. The presence of sweat and menstrual blood increases the moisture level and the adhesion of liquid to textile causing sensorial discomfort. This study describes the design and uses of modified Textile Stickiness Measurement System (TSMS) which can characterize the frictional properties of sanitary pads under both dry and wet conditions. The uniqueness of this measurement system is that the wetness level of the pad is adjustable and the surface profile of the contacting object (i.e. LoricaÂŽSoft) does simulate the condition of human skin. Also, it does not have restriction on the type of sanitary pad that can be tested. Among the 12 sanitary pads tested (disposable and reusable types), the frictional force for the disposable sanitary pads is lower than the reusable pads whilst the performance of disposable sanitary pads with nonwoven surface is lower than the one with perforated surface. These can attribute to their liquid transport property and surface feature. For those with better liquid transport property, less water will stay on skin surface and so the adhesion between skin and textiles is lower. For those with protruding fibers on its surface, it reduced the contact area and so the frictional force is lower. Estimation of basis weight, ash content and moisture content in papermaking plants: A comparative study, Beom Seok Kim, Tae Chang Park & Yeong Koo Yeo, Korean Journal of Chemical Engineering, 37, 2020, https://doi.org/10.1007/s11814020-0549-7. The papermaking process is a typical nonlinear process with multiple inputoutput variables, so it is difficult to construct an accurate model for the process. Databased modeling techniques may be used to establish a reliable paper plant model. In particular, the LSSVM (least-squares support vector machine) can be used to create a highperformance papermaking process model based on operation data. In this paper, we present a paper plant model that can predict three key output variables (basis weight, ash content, moisture content) with four input variables (stock flow, filler flow, speed, steam pressure) using LSSVM. The proposed LSSVM model is compared with other data-based models (the ANN (artificial neural network) model and the state-space model). The LSSVM model turned out to exhibit better estimation performance compared to others. TISSUE Influence of tissue paper converting conditions on finished product softness, de Oliveira Mendes, A., Vieira, J.C., Carta, A.M., Galli, E., SimĂľes, R., Silva, M., Costa, A.P., and Fiadeiro, P.T., BioResources, 15(3), DOI: 10.15376/biores.15.3.71787190.Tissue paper conversion consists of the transformation of base tissue papers into finished tissue products to meet specific demands. When base tissue paper arrives at the converting line, it already holds different requirements that were met during its manufacture in the paper machine (e.g., grammage, bulk, tensile index, etc.). However, what happens during converting can still influence the performance and quality of the finished products. The current work addresses this topic and aims to evaluate the influence of converting conditions on the final softness. For that, two 5-ply finished tissue products were analyzed using different methodologies for their proper characterization in terms of softness and surface analysis. The analyzed products are composed by the same base tissue papers, but some changes were applied on their settings in the converting line. In particular, the base tissue papers arrangement and the embossing pressure affected the finished products, resulting in one of them being softer and more pleasant to touch, with a global handfeel (HF) value of 75.3 units, and the other revealed to be rougher and less pleasant, with a global handfeel (HF) value of 68.0 units. Page 10 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

Impact of 5-Ply toilet paper configuration on its mechanical and absorption properties, Costa Vieira, J., Mendes, A., Carta, A., Fiadeiro, P., and Costa, A. BioResources, 15(4), DOI: 10.15376/biores.15.4.7475-7486. Several physical and mechanical properties can characterize tissue papers. In particular, low grammage but high values of bulk, flexibility, liquid absorption capacity, and softness are common properties for tissue papers. These properties must be adapted to meet the requirements of the final consumer, which can vary greatly in different countries. This work resulted from a study regarding the impact of two different stacking sequences of 5-ply toilet paper with configurations 1 and 2 (deco:micro embossing of 3:2 and 2:3 plies, respectively), which had the same base tissue papers in each mother reel, on their mechanical behavior and absorption capacity. The stacking sequence of the plies influenced the properties of the finished toilet paper. For configurations 1 and 2, after the embossing process, bulk increases of 46% and 40%, respectively, and water absorption capacity increases of 2% and 17%, respectively, were registered. In this case, the bulk increase was not the key property that influenced the water absorption capacity. Regarding mechanical properties, both configurations showed a higher negative impact caused by the deco embossing. For commercial purposes and to adhere to the final consumersâ€™ preferences for toilet paper, configuration 1 was more suitable for mechanical strength, and configuration 2 was more suitable for absorption capacity. 3D fiber models to simulate and optimize tissue materials, Morais, F.P., Carta, A.M. N.S., Amaral, M.E., & Curto, J.M.R., BioResources, 15(4), DOI: 10.15376/biores.15.4.8833-8848. Tissue materials development using 3D computational tools to predict the influence of the combination of different fibers can be employed in the design of innovative tissue products and furnish optimization. Fibrous materials can be designed using different 3D fiber models for each type of fibers, detailed to the point where the wall fiber thickness, fiber lumen, and collapse degree are considered and presented in this work. Eucalyptus, Pinus, and Picea kraft cellulose pulp fibers were selected because they are representative of differentiated fiber types. The fiber morphological measurements were obtained using two methods: one uses the fibers in suspension, without restraints, and the other uses a capillary fiber alignment. The results indicate good repeatability for both methods but differences of 14% for fiber length weighted in length, 2% for fiber width, 11% for coarseness, 35% for curl, and 88% for fines content. Scanning electron microscopy images were used to identify the fiber dimensions inside the tissue structure. Four different types of fiber models for eucalyptus fibers, with different fiber wall thickness and lumen dimensions, were presented and used to predict 3D computational fibrous structures. WASTE TREATMENT A novel effluent quality predicting model based on genetic-deep belief network algorithm for cleaner production in a full-scale paper-making wastewater treatment, Guoqiang Niu, Xiaohui Yi, Chen Chen, Xiaoyong Li, Donghui Han, Bo Yan, Mingzhi Huang & Guangguo Ying, Journal of Cleaner Production, 265, Aug. 2020, https://doi.org/10.1016/j.jclepro.2020.121787. Recycling wastewater of the pulping and paper-making industry are widely considered for clean production, which heavily rely on the timely and accurate monitoring in paper-making wastewater treatment processes. A novel predicting model based on genetic-deep belief network algorithm was proposed to improve the predictive accuracy and reliability for process monitoring. Considering the deep belief networks (DBN) as a deep learning model is aiming to describe the relationship among variables in a complex process modeling, genetic algorithm (GA) was employed to reduce the input variables dimensionality, simplify the network structure and Page 11 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

overcome the dynamic characteristic difficulties of process data in monitoring. Compared with DBN and back propagation neural network (BPNN), the GA-DBN effectively achieved a better predictive accuracy than other tests models in complex wastewater treatment processes. The value of the coefficient of determination of GA-DBN model is increased by 1.71–1.86% and 5.21–9.32%, respectively. The GA-DBN model can be structured with fewer variables or samples to describe the complex paper-making wastewater treatment process, obtaining the better model performance and predictive accuracy. Superefficient removal of lignins from papermaking wastewater by polycationic adsorption and direct reuse of wastes: structure–activity relationships and interaction mechanisms, Yu Bai, Hongyan Li, Qiwen Yang, Yikai Yu & Bingxian Peng, Journal of Cleaner Technology and Biotechnology, 95(11), Nov. 2020, https://doi.org/10.1002/jctb.6460. This work first found a strong adsorbent for highly efficient removal of lignins and realized the direct reuse of its wastes. Through systemically screening the serial molecular structures of polycationic adsorbents previously developed, a highly permeable polycationic gel (PPG) adsorbent was discovered to be the most suitable for lignin removal. The maximum adsorption capacity of PPG for the lignins was 3891.65 mg/g, that is, the masses of adsorbed lignins were 3.89 times higher than that of PPG. Interestingly, after adsorbing the lignins, PPG wastes could be directly reused, without any treatment, for purifying dyeing wastewater. The adsorption capacity of PPG wastes reused for adsorbing the anionic dyes was 245.05 times higher than that of the existing activated carbon, indicating that PPG wastes maintained excellent adsorption ability for purifying the dyeing wastewater. A series of simulation experiments and instrument analyses were carried out to detect the new adsorption effect of PPG. The high waterǦpermeability of PPG allows for complete permeability of the lignins and easy adsorption inside PPG. After adsorption, shrinkage of the internal structure of PPG and aggregation of the adsorbed lignins on the surface of PPG enhanced the adsorption intensity of PPG toward the lignins. Conclusion: This indicated that PPG had a superǦhigh adsorption ability for direct removal of lignins from water by adsorption, which marked the first successful report of reused wastes utilized for treating other waste pollutants. Demonstration on the treatment of paperǦmaking wastewater by a fullǦscale ICǦA/OǦ membrane reactor system for reclamation, Haifeng Zhuang, Zhong Cheng, Shengdao Shan, Haitao Shen & Bingjun Zhao, Journal of Chemical Technology and Biotechnology, 95(12), Dec. 2020, https://doi.org/10.1002/jctb.6494. In this study, the performance of a fullǦscale internal circulation–anoxic/oxic (ICǦA/O)–ultrafiltration (UF)– reverse osmosis (RO) membrane system for reclamation and reuse of paperǦmaking wastewater was investigated. Results showed that the integrated system presented a stable and highly efficient performance. The effluent concentrations of chemical oxygen demand, total organic carbon, biochemical oxygen demand, NH4+ nitrogen and total nitrogen were 12, 4, 0.3, 0.5 and 2.9 mg L−1. gas chromatographic–mass spectrometric results showed that the organic composition in each process of the ICǦAOǦUFǦRO system varied significantly. Acute biological toxicity was obviously reduced, with an effluent toxic unit value of 3.11. The results of particle size distribution indicated that anaerobic granular sludge (around 3 mm) was formed in an IC reactor. Anaerolinea, Propioniciclava and Thauera were the main contributors to pollutant removal. Advanced treatment by the UFǦ RO system achieved complete removal of suspended solids, silt density index and turbidity with little hardness and conductivity in the final effluent, which allowed for reclamation of paperǦmaking wastewater. Conclusion: Water reuse and energy recycling were successfully realized in the builtǦup ICǦAO–membrane reactor system. Page 12 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

Catalytic ozonation treatment of papermaking wastewater by Ag-doped NiFe2O4: Performance and mechanism, Junyu Zhao, Jiashun Cao, Yujie Zhao, Teng Zhang, Di Zheng & ChaoLi, Journal of Environmental Sciences, 97, Nov. 2020, https://doi.org/10.1016/j.jes.2020.04.014. The catalytic ozonation treatment of secondary biochemical effluent for papermaking wastewater by Ag-doped nickel ferrite was investigated. Ag-doped catalysts prepared by sol-gel method were characterized, illustrating that Ag entirely entered the crystalline of NiFe2O4 and changed the surface properties. The addition of catalyst enhanced the removal efficiency of chemical oxygen demand and total organic carbon. The results of gas chromatography-mass spectrometer, ultraviolet light absorbance at 254 nm and three-dimensional fluorescence excitationemission matrix suggested that aromatic compounds were efficiently degraded and toxic substances, such as dibutyl phthalate. In addition, the radical scavenging experiments confirmed the hydroxyl radicals acted as the main reactive oxygen species and the surface properties of catalysts played an important role in the reaction. Overall, this work validated potential applications of Ag-doped NiFe2O4 catalyzed ozonation process of biologically recalcitrant wastewater. Feasibility and safety of papermaking wastewater in using as ecological water supplement after advanced treatment by fluidized-bed Fenton coupled with largescale constructed wetland, Liqun Xing, Ming Kong, Xianchuan Xie, Jie Sun, Dongyang Wei & Aimin L, Science of the Total Environment, 699, Jan. 2020, https://doi.org/10.1016/j.scitotenv.2019.134369. Reuse of pulp-and-paper industry wastewater as reclaimed water is an effective way to mitigate water resource shortage. In this study, the feasibility and safety of papermaking wastewater for the use as ecological water supplement after the treatment by fluidized-bed Fenton (FBF) coupled with constructed wetland (CW), were investigated from laboratory-scale to large-scale field. The optimum pH, H2O2, H2O2/Fe2+ ratio and hydraulic retention time (HRT) of FBF were 3.5, 0.93 mL/L, 4 and 60 min, respectively, based on reduction of both total organic carbon (TOC) and genotoxicity. Furthermore, the safety of effluent was evaluated using SOS/umu assay and 8-hydroxy-2-deoxyguanosine (8-OHdG) in zebrafish. Results showed FBF followed by CW improved the conventional water quality indicators and reduced the toxicity. Average removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN), total phosphorus (TP) and colority were 87.3%, 93.59%, 51.73%, 84.75% and 95.86%, respectively. The equivalent concentration of 4nitroquinoline 1-oxide (4-NQO-EQ) decreased from 30.6 ± 1.6 μg/L in influent to 12.4 ± 1.0 μg/L after treated by FBF, then decreased to 5.9 ± 0.4 μg/L after treated by CW and to 3.2 ± 0.3 μg/L after 12-km downstream self-purification. The chronic survival rates of 21-d zebrafish significantly increased from 0.0% in influent to 58.8 ± 4.0% in effluent of CW and gradually increased to 68.8 ± 2.6% after 12-km downstream self-purification. Similarly, 8-OHdG level in zebrafish decreased from 120.0 ± 19.3 ng/L in effluent of ecological oxidation pond to 94.0 ± 7.5 ng/L in effluent of CW and gradually decreased to 42.0 ± 3.0 ng/L after 12-km downstream self-purification. The study concluded that FBFCW is an efficient detoxication and water quality improvement technology for papermaking wastewater to be used as an ecological water supplement. Impact of persulphate mixed with paper sludge on activated sludge dewaterability, Sen Wang, Saige Cheng, Xueli Xiao & Fan Lai, Water and Environment Journal, online, https://doi.org/10.1111/wej.12597, FeSO4 was used to activate K2S2O8 mixed with paper sludge to condition activated sludge, and its effect on sludge dewaterability was investigated. Interaction effects of various parameters on sludge dewaterability were investigated and analysed by considering the moisture content of cake, specific resistance Page 13 of 15

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2020

to filtration (SRF) and capillary suction time (CST) as indicators and the Box–Behnken design of response surface methodology (RSM). Results indicated that the moisture content of cake, SRF and CST decreased from 74.52 to 69.57%, 25.39 × 1012 to 11.80 × 1012 m/kg and 199.8 to 146.4 s, respectively, under optimal conditions. RSM results presented that only 0.13% of the response values cannot be interpreted with this model, and the threeǦfactor interaction was observed to be significant. Additionally, sludge dewaterability mechanism observed that K2S2O8 mixed with paper sludge used the strong oxidising properties of SO4−• to crack sludge flocs. Fine fibres and calcium carbonate in the paper sludge played important roles as the skeleton support in the sludge filtration process, and the internal moisture was rapidly eliminated. WOOD PANEL Tuning of adhesion and disintegration of oxidized starch adhesives for the recycling of medium density fiberboard, Lubis, M.A.R., Park, B., and Hong, M., BioResources, 15(3), DOI: 10.15376/biores.15.3.5156-5178. Oxidized starch (OS) adhesives with a balance between their adhesion and disintegration properties were prepared by controlling the degree of oxidation and modifying the cross-linker type and level to replace ureaformaldehyde (UF) resins for easy recycling of medium density fiberboard (MDF). Four molar ratios of H2O2/starch, two types of cross-linker, i.e., blocked-pMDI (B-pMDI) and citric acid (CA), and three levels of the cross-linkers were employed to tailor the performance of the OS adhesives. The OS reacted with the isocyanate groups from the BpMDI to form amide linkages, while it formed ester linkages by reacting with the CA. The resulting B-pMDI/OS-bonded MDF had better physical and mechanical properties than the CA/OS-bonded MDF, with comparable adhesion (0.34 MPa) to UF resins and ten times greater degree of fiber disintegration than UF resins. The combination of a 0.5 molar ratio OS with 7.5 wt% of B-pMDI produced MDF exhibiting an optimal balance between adhesion and disintegration, suggesting that such OS adhesives could someday replace UF resins in manufacturing and recycling of MDF without formaldehyde emission. Properties evaluation by thickness and type of oriented strand boards manufactured in continuous press line, Zeleniuc, O., Dumitrascu, A.-E., and Ciobanu, V.D., BioResources, 15(3), DOI: 10.15376/biores.15.3.5829-5842. Oriented strand boards (OSB) are widely used in construction replacing plywood. There are four types of boards (OSB/1, OSB/2, OSB/3, OSB/4) carried out depending on the conditions of uses. The present research aimed to evaluate the physical and mechanical performance of these types of boards, with 10 mm, 11 mm, 18 mm and 22 mm thicknesses. The boards were industrially manufactured using the continue press line. The results showed that the compression grade increased with decreasing of the wood strands densities, from 1.3 (OSB/1) to 1.1 (OSB/3). Thickness swelling values were lower for OSB/3 and OSB/2 with 35% and 14%, when compared to OSB/1. For these boards a slight increase in adhesive content and a lower speed of pressing line was set considering that they are designated for the exterior use. An increase in density with about 7.6% led to an increase with about 19% of modulus of rupture (MOR), when compare OSB 10 mm with OSB 22 mm. Improvements with 27% to 22% MOR and 13% to 10% modulus of elasticity (MOE) in case of OSB/3 and OSB/2 compared to OSB/1 were found. Internal bond (IB) values were with about 32% higher for OSB/3 than those reached by OSB/1 and the thinner boards registered 25% higher IB values even after boiling test, compared to the thicker ones.

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FROM THE PUBLISHERS OF PA APER TECHNOLOGY Volume 6, Number 2, 2019

The potential of using forest waste as a raw material in particleboard manufacturing, Şahin, H., BioResources, 15(4), DOI: 10.15376/biores.15.4.7780-7795. Wood particles and a mixture of forest waste were investigated as raw material for the particleboard industry. Urea formaldehyde resin was used as the adhesive in the production of the particleboards. Some chemical (pH, dilute alkali solubility, hot and cold water solubility), physical (density, moisture, thickness swelling, and water absorption), mechanical (modulus of rupture, modulus of elasticity, internal bond strength, and screw holding strength) properties, as well as the contact angle values of the resulting particleboards were determined. Due to its needle litter and cone content, the forest waste exhibited a lower pH value and a higher content of extractive material than wood. Increasing the addition of forest waste led to significant reductions in the physical and mechanical properties of the particleboards. The addition of forest waste reduced the internal bond strength the most (56.6%), whereas the least reduction (15.7%) was in the value of screw holding strength perpendicular to the surface. The values of all panels except panel type F exceeded the minimum modulus of elasticity (1600 N mm-2) required for furniture production according to the EN 312-P2 standard. Results of the analyses showed that forest waste (10% and 20%) is a suitable renewable raw material source for panel production. Adhesive application on particleboard from natural fibers: A review, Amina Adedoja Owodunni, Junidah Lamaming, Rokiah Hashim, Owolabi Folahan Abdulwahab Taiwo & Mohd Hazwan Hussin, Mohamad Haafiz Mohamad Kassim, Yazmin Bustami, Othman Sulaiman, Mohd Hazim Mohamad Amini & Salim Hiziroglu, Polymer Composites, 41(11), No.20, https://doi.org/10.1002/pc.25749. Impending health challenges in the formulations of particleboards from cellulosicǦbased waste particles such as wood chips, sawdust, and veneer boards are of great concern. These wastes are majorly bonded together with synthetic resin or binder in the presence of heat and pressure to produce particleboards of various specifications and sizes depending on the endǦuse. The qualities of the particleboards depend on the modification of the particle geometry, resin levels, board density, and manufacturing processes. The addition of special additives to enhance the qualitative performance of particleboards such as dimensional stability, fire retardancy enhancement, and moisture resistance is included in the manufacturing process. The milestone in the use of wood particles for particleboard manufacture is the large reduction in the environmental hazard that these abundant wastes cause. Furthermore, this review reports recent research efforts in the use of green adhesives to reduce the health threat related to utilizing formaldehydeǦbased particleboard. The use of adhesives produced from natural sources has contributed toward the reduction in the impending health challenges and the cost of building construction by using such a particleboard.

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Volume 6 Number 2, 2020

PITA TRAINING COURSES for 2021 As might be expected, physical face-to-face events will remain impossible for the foreseeable future. Nevertheless, after the success of our first ‘virtual’ training course held in November 2020, we are determined to press ahead with others next year. To date we already have one new event planned, and more will follow shortly. (Up to date information can be found on The PITA Calendar.) PITA ‘Energy Optimisation’ Course (online) 24-25 Feb. 2021

CONFERENCES / EXHIBITIONS for 2021 Many events planned for earlier this year were cancelled, some were re-scheduled for later this year or next, and a few have since been rescheduled again as exhibition companies wax and wane in their enthusiasm and confidence. With the recent positive news about vaccines, it seems likely that some semblance of normality will return sometime next year. A few exhibitions have already stated their intentions to run physical meetings in 2021, and these are listed below. (Up to date information can be found on The PITA Calendar of World Events.) DRUPA (Düsseldorf)

20-28 Apr.

(Printing)

PulPaper (Helsinki)

27-29 Apr.

(General)

Zellcheming (Wiesbaden)

9-10 June

(General)

Tissue World Europe (Düsseldorf)

21-23 Sept. (Tissue / Hygiene)

MIAC 2021 (Lucca)

13-15 Oct.

(General / Tissue & Hygiene)

Paperex 2021 (New Delhi)

6-9 Dec.

(General)

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Events for 2021

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Volume 6, Number 2, 2020

(1) PULPAPER TO HIGHLIGHT DIGITALISATION, RESPONSIBILITY AND NEW TEXTILE PRODUCTS The leading forest-industry event PulPaper will, in its conference programme, highlight key talking points in the industry right now. Featuring top Finnish and international speakers, the event will cover topics such as the environment and sustainability, energy efficiency, and safety in the industry. PulPaper will be held at Messukeskus in Helsinki from 27 to 29 April 2021. The conference programme of the forest-industry event PulPaper, to be held next spring, will include the most interesting topics in the industry, on the theme of Building tomorrow’s bioeconomy. The conference programme will be divided into sub-topics, so that it is easy for participants to choose the topics that interest them most among the speeches. In the IT and automation sub-topic, discussion will focus on the opportunities offered by digitalisation in the forest industry, with special focus on investments in the industry. In the safety and risk management sub-topic, the issues highlighted include the creation of a safety culture in the forest industry and the continuous development of risk management of recovery boilers. The efficiency of the industry will also be addressed in the conference programme, through examples of smart and proactive maintenance, optimising energy balance at mill integrates, and the continuous development of operations. The environment and responsibility are also major talking points in the forest industry. At PulPaper, these are discussed, for example, in relation to the benefits, challenges and recyclability of bio-based materials. The forest industry is also increasingly expanding into textiles, and the use of recycled paper as a textile fibre will feature in several speeches. Another topical issue in the forest industry is packaging solutions, and, in this area, the event will present the possibilities of nanocellulose in food packaging, and current developments in eucalyptus-based packaging products. “The forest industry can offer many concrete solutions to global challenges. These solutions will build the sustainable bioeconomy of the future, which we want to discuss at PulPaper”, says Antti Lindqvist, the managing director of the Forest Products Engineers association. The final, full programme of the event will be published at the end of this year. (2) ZELLCHEMING-EXPO 2021 With the foundation of ZELLCHEMING Service GmbH, the reorientation of the ZELLCHEMING Association with a clear separation between voluntary association life and economic activities is now officially completed. Behind the scenes, work has already been going on for several weeks to prepare the starting signal for the ZELLCHEMING-Expo in June 2021, which is organized and handled by the GmbH as organizer, in the best possible way. Information material and documents are available and the starting signal for the exhibitor acquisition has already been given. The Expo website has also gone live for visitors and exhibitors from Germany and abroad. Positive Response "The initial response has been very positive: A number of exhibitors have already confirmed their participation and the reserved area is already higher than that which was booked for the Expo planned for 2020 in the same period," explains Petra Hanke, Managing Director of ZELLCHEMING Service GmbH. Page 2 of 4

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Volume 6, Number 2, 2020

"We are experiencing that many representatives of our industry feel the desire to meet again with suppliers and industry colleagues in personal discussions and are confident that we will be able to meet this need, also in view of our sophisticated hygiene concept". The multifunctional RheinMain CongressCenter in Wiesbaden offers plenty of space for a wide variety of events and functions such as trade fairs, congresses, and conferences as well as digital formats and is advertised as a "feel-good location". Petra Hanke: "The fact that we are returning to a proven and popular location, which at the same time presents itself in a completely new and contemporary way, also generates a great deal of positive interest". Over two full days, on June 9 and 10, 2021, visitors to the ZELLCHEMING-Expo will be able to follow practice-oriented presentations and obtain information and further training on specific topics and applications. The lectures, which will be presented in the course of the event, pick up current approaches of the paper- and cellulose-based industry on the way to a climate-friendly bio-economy and give further impetus to ideas and initiatives beyond the event. Exhibitors are involved via best-practice applications and the latest technologies for process and product innovation. The detailed program will be presented in the coming weeks. Stronger integration of scientific and technical work A further aspect of the spin-off of the economic business activities into the GmbH was the desire to re-focus the association on scientific and technical work and thus sharpen its profile as an important link between research and industry. In this context, the link with the ZELLCHEMING-Expo is also to be strengthened - in which the results of the ZELLCHEMING working groups will be presented to a broad expert audience for the first time in the context of a forum at the Expo. Which steps could be taken for this purpose in the technical committees and district groups has already been discussed in a future workshop", explained Gerrit Lund, 1st Chairman of the ZELLCHEMING Association. ZELLCHEMING-Expo Website Visitors and exhibitors can obtain information about the event on the website: www.zellcheming-expo.com (3) TISSUE WORLD DĂœSSELDORF RETURNS IN SEPTEMBER 2021 In September 2021, Tissue World will make its stop for the very first time in DĂźsseldorf, Germany. The trade show and conference is the flagship show of Tissue World, the leading global event series serving the tissue industry worldwide since 1993. The biennial event provides an international platform for tissue manufacturers, converters, jumbo roll suppliers and an exhaustive range of industry suppliers to network and source for the latest tissue industry technologies and solutions. (4) PAPEREX - A UNIFIED BUSINESS PLATFORM FOR PAPER INDUSTRY Paperex is an internationally renowned series of exhibitions and conferences focusing on Paper, Pulp and all Allied Industries. It is the only comprehensive business platform serving the paper industry and over the years, this leading business event has become the Page 3 of 4

Events for 2021

PAPERmaking! g FROM THE PUBLISHERS OF PAP PER TECHNOLOGY INTERNATIONAL

Volume 6, Number 2, 2020

perfect platform for showcasing the entire spectrum of products and services relating to the Paper and Allied Industries. At Paperex, one gets to witness latest technology, machinery and raw material for paper & board manufacturing: complete paper mill machinery, automation & instrumentation, bearing & accessories, boilers & turbines, industrial gears, rolls & rollers, pumps valves & systems, quality control equipment & system, raw material handling, stock preparation equipment, testing equipmentâ€™s, transport & material handling. The show hosts buyers from paper & board manufacturers, paper traders, printers, publisher, converter and paper packaging companies, designers for corrugated box & related packaging, investors & promoters. The Paperex series of exhibition and conference has always been a gratifying experience in terms of organization, participation, and generation of new business opportunities in the field of Paper, Pulp and allied industries. The steady growth of the event, which has already seen 14th editions, is a reflection of the increasing capabilities as well as the potential for new technologies and investments in the Paper, Pulp and Allied Industries. An interesting dimension to the popularity of Paperex has been the expanding international interest. This is evident from the growing numbers of participants as well as visitors from countries across the globe. Paperex also credits its growth to the active support & patronage of both Indian and the International Paper Industry and Associations

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Events for 2021