Development of Biodegradable Polyurethane Footwear Soling Materials G. Saraswathy, Scientist, CSIR- CLRI, India 15. 11.2013
Council of Scientific and Industrial Research (CSIR)
MISSION  To provide scientific industrial R&D that maximises the economic, environmental and societal benefits for the people of India.
CSIR-Central Leather Research Institute
(Council of Scientific and Industrial Research)
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Recent Head Lines
Coffee industry responsible for significant plastic litter Food packaging industry can do a lot better Plastic bottles litter the solar system Super markets hand out 8 billion plastic bags- UK Footwear industry ………….!
Social ResponsibilityChallenges of Footwear Industries
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Wastes generated by the footwear manufacturing - % of world areas North and C e n t r a l A m e ric a 5 % South A m e r i c a 7%
Rest of the wo r l d 3 %
Western E u ro p e 1 0 % C h in a 47% Eastern E u r o p e 3 % Middle E a s t 3 %
Asia (excl. C h in a ) 2 2 %
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Biodegradable Shoes / Simple Shoes
The shoe raw materials and packaging come from Vegetable origin polymers Fossil organic matter Natural fibre Recycled cardboard Pigments
1. The upper is pieced together from leather and synthetic leather waste from the factory floor using zig-zag stitching. 2. The mid-sole - scrap-ground foam from factory production. 3. The outsole uses environmentally-preferred rubber and Nike Grind material 4. Packaged in a fully recycled cardboard shoe box.
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
What about‌
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
General Solutions for Waste Management 4R’s
Reduce Reuse
Wear them around / Sell them / Donate them
Recycle Collecting from post-consumers (Nike)
Separated by materials - Upper fabric - Midsole foam - Outsole rubber Floors of Basket ball court/ Playground surfacing/ Running tracks
Energy recovery – Heat/ Power
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Rejuvenate  Rejuvenation using landfill biodegradable additives to make plastics fade away.  Shoe soles - Land fill -??? Footwear Soling Materials
Percentage (%)
Leather
8
Polyurethane (PU)
8
Thermoplastic Rubber (TPR)
14
Ethylene Vinyl Acetate (EVA)
9
Poly (Vinyl Chloride) (PVC)
20
Rubber
40
Others
1
Ref: Staikos T, Rahimifard, S. A decision-making model for waste management in the footwear industry. Intl J Production Res 2007; 45 (18): 4403-4422.
What is Biodegradability?  Biodegradability is characteristic of natural substances and materials being assimilated by micro-organisms, and thus introduced into the natural cycles.  Biodegradability testing determines the potential rate of degradation by biological processes in the environment.
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Need of Biodegradable Shoe Soling material Though polyurethane is used only 8% of the global production of shoes and this figure continuous to rise for its unique mechanical properties. Therefore footwear/ polymer industries have started to develop low cost PU to replace the conventional polymer soles. The polymeric shoe soles create an enormous amount of waste that is currently being disposed as landfill.
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Objective of the project  To prepare and characterize biodegradable polymer composites based on PU.  To determine the physical, mechanical and degradation properties of prepared polyurethane materials for application as shoe soling material.
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Experimental Procedure Materials:
Synthesis of Segmented PU Prepolymer Method
Polyol: Polycaprolactone diol (PCL diol). Diisocyanates: 4,4’-methylenediphenyl diisocyanate
2O
(MDI), Hexamethylene diisocyanate (HMDI), Toluene
C
R
N
C
N
O
HO
OH
R'
diisocyanate (TDI), and Isophorone diisocyanate (IPDI).
Chain Extender: Ethylene diamine (ED),1,4-Butane diol (BD), N-Methyl diethanol amine (MIDE), Triethanol amine (TEA).
Catalyst: Dibutyltin dilaurate (DBTDL).
OCN
Solvents: Dimethyl formamide (DMF).
R
H
O
N
C
O
Nanoparticles: Nanoclay and Titanium dioxide.
R'
O
O
H
C
N
R
NCO
O
R"
prepolymer
Thermoplastic polyurethane (CPU) prepared using PCL as one of the polyol, from Sigma.
reaction with diol HO
O
R"
O
R'
OH
O
H
H
O
C
N
N
C
polyurethane
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
O
PREPARATION OF PU SHEET BY CASTING After completion of two step synthesis of segmented polyurethanes, the polymer solution was poured into glass dishes and dried at 60 째C for 24 h and then stored in desiccator until use.
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Types of PUs synthesized in the laboratory
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Preparation of PU Composites Properties of Nanoclay (MMT) Chemical Name: Hydrated sodium calcium aluminum silicate Nominal Chemical Composition (%): Al= 9.98, Si= 20.78, H= 4.10 and 0=65.12 Powder as fine as 20 nanometers Molecular Weight (g/mol.): 540.46 Average Density (g/cm3): 2.35 Crystal System: Monoclinic Abundantly available Eco-friendly and cost effective
Properties of TiO2 Nanopowder Appearance: White solid Average Density (g/cm3): 4.23 Contents: Rutile-30-40 wt %; Anatase-60-70 wt % Partical Size: 10-30 nm SSA: 50-100 m2/g Crystal system: Tetragonal
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
List of PU composites developed in the laboratory Sl. No
Sample Code
Description
1.
CPU Control
15 % CPU 430218 (15 g of CPU in 100 ml of DMF)
2.
CPU- NC 1%
15 % CPU : NC 1 % (15 g of CPU : 0.1 g NC in 100 ml of DMF)
3.
CPU- NC 2%
15 % CPU : NC 2 % (15 g of CPU : 0.2 g NC in 100 ml of DMF)
4.
CPU- NC 4%
15 % CPU : NC 4 % (15 g of CPU : 0.4 g NC in 100 ml of DMF)
5.
CPU- NC 6%
15 % CPU : NC 6 % (15 g of CPU : 0.6 g NC in 100 ml of DMF)
6.
CPU- TD 1%
15 % CPU : TD 1 % (15 g of CPU : 0.1 g NC in 100 ml of DMF)
7.
CPU- TD 2%
15 % CPU : TD 2 % (15 g of CPU : 0.2 g NC in 100 ml of DMF)
8.
CPU- TD 4%
15 % CPU : TD 4 % (15 g of CPU : 0.4 g NC in 100 ml of DMF)
9.
CPU- TD 6%
15 % CPU : TD 6 % (15 g of CPU : 0.6 g NC in 100 ml of DMF)
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
SEM Pictures
The outer surface morphology and corresponding cross section at 1000 magnification of Samples A) SPU, B) SPU 2% NC, C) SPU 2% TD, D) CPU 2% NC and E) CPU 2% TD. G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Biodegradability Test by Soil Burial Method
The soil burial test was carried out in two different soils (red and normal soil) of same locations at garden (CLRI campus). The percentage weight loss of the test films was calculated by using the relationship: Weight loss (%) = ((Wi –Wf) / Wi) x 100 where Wi = initial weight Wf = final weight of the test sample.
Sample A- PU based on MDI:PCL:BD Sample B - PU based on MDI:PCL:MIDE Sample C- CPU 430218 from Sigma
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Biodegradability Test Results Weight Loss (%) 14 12 30 days
10 % Weight Loss
8
45 days
6
60 days
4
90 days
2 0
A
B
C
Sample Code
A – SPU (MDI:PCL:BD), B – SPU (MDI:PCL:MIDE), C - CPU (430218)
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Loss of Tensile Strength
Tensile strength, MPa
18 15 12
30 days
9
45 days 60 days
6
90 days
3 0
A
B
C
Sample code A – SPU (MDI:PCL:BD), B – SPU (MDI:PCL:MIDE), C - CPU (430218)
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Physico-Mechanical Properties of PU sheets as Soling Materials • • • • •
Hardness Density Tensile strength Tear strength Abrasion resistance
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Hydrolysis Sample code
Thickness (mm)
Tensile strength (MPa)
SPU Control SPU Hydrolysed
0.21
7.66
0.21
3.72
23.67
CPU Control
0.59
15.82
823.33
CPU Hydrolysed
0.93
13.62
Elongation Reduction in at break Tensile strength (%) after hydrolysis (%)
Change in Elongation after hydrolysis (%)
5.89 51.44
301.87
13.9
57.87
346.89
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Summary & Conclusion • Biodegradable PUs having material properties required for soling material were prepared. • The standard stoichiometric ratio of 2:1:1 was optimized for synthesis of biodegradable PU using HMDI: PCL: BD composition. • In order to improve the mechanical properties, nanoparticles were added to commercial and synthesized polyurethanes in various concentrations. • The concentration of nanoparticles was optimized. Other ingredients which are normally used in the preparation of PU soles were not used in the preparation of PU nanocomposites. • The PU sheets developed with 2% concentration of nanoclay (NC) and Titanium dioxide (TD) had shown better mechanical properties than the other PU sheets. • The mechanical properties of composites are found to meet the standard specifications for soling materials. G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013
Acknowledgement Organizers – UITIC - CLIA DST, Govt. of India The Director, CSIR-CLRI
THANK YOU FOR YOUR KIND ATTENDTION
G. Saraswathy- Development of Biodegradable Polyurethane Footwear Soling Materials- 15.11.2013