IM20214EN

Volume 4 2021

WORLD FIRST: 3D-PRINTED STEEL BRIDGE NEW GENERATION OF BIOBASED POLYESTERS FOR DURABLE PRODUCTS RENEWABLE LIGHTWEIGHT PADDLEBOARD AUXETIC CONCRETE TAKES ENERGY FROM THE SEA ORIGAMI GLASS NEW LIQUID CRYSTAL INK FOR 3D PRINTING

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CONTENT About

Innovatieve Materialen (Innovative Materials) is a digital, independent magazine about material innovation in the fields of engineering, construction (buildings, infrastructure and industrial) and industrial design.

A digital subscribtion in 2021 (6 editions) costs € 40,70 (excl. VAT) Members of KIVI and students: € 25,- (excl. VAT)

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Innovative Materials platform: Dr. ir. Fred Veer, prof. ir. Rob Nijsse (Glass & Transparency Research Group, TU Delft), dr. Bert van Haastrecht (M2I), prof.

Wim Poelman, dr. Ton Hurkmans (MaterialDesign), prof.dr.ir. Jos Brouwers, (Department of the Built Environment, Section Building Physics and Services TU Eindhoven), prof.dr.ir. Jilt Sietsma, (4TU.HTM/ Mechanical, Maritime and Materials Engineering (3mE), Kris Binon (Flam3D), Guido Verhoeven (Bond voor Materialenkennis/SIM Flanders, Prof. dr. ir. Christian Louter (Institut für Baukonstruktion Technische Universität Dresden).

16 World First: 3D-printed steel bridge opened

On 15 July, Queen Máxima opened the world’s first 3D-printed steel bridge in Amsterdam. The bridge was manufactured by the Amsterdam scale-up MX3D and is placed on the Oudezijds Achterburgwal in Amsterdam. The bridge is a prize-winning design by Joris Laarman Lab and the result of a collaboration between, among others, MX3D, software company Autodesk, chief engineer Arup, steel concern ArcelorMittal, the Municipality of Amsterdam and the University of Twente.

18 New generation of biobased polyesters for sustainable products

To introduce biobased polyesters for high-performance applications, such as automotive and electronics, Wageningen Food & Biobased Research (WFBR) is developing a new generation of biobased polymers based on the molecule isoidide.

20 Paddleboard made from renewable lightweight materials

Conventional surfboards are made from petroleum-based materials such as epoxy resin and polyurethane. Researchers from the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut, WKI, now want to replace plastic boards with a sustainable alternative, by developing a stand-up paddleboard made entirely from 100 percent renewable raw materials.

22 Auxetic concrete draws energy from the sea

Waves crashing against the coast generate energy. Researchers Branko Šavija and Yading Xu of TU Delft want to capture this energy by means of a special type of concrete and thus create an alternative energy source. It concerns auxetic concrete, a flexible concrete that has a special property. Under pressure load it contracts, but when that load disappears, it expands like a kind of sponge. Perhaps this property can be used to generate energy using concrete sea walls.

25 Origami Glass: complex glass geometric structures

Glass is a great material in many ways, but the detailed design of glass products is not easy. This has to do with the brittle properties of the material and the high temperatures at which the (conventional) molding processes work. Researchers from China’s Zhejiang University have now developed a method that makes it possible to create three-dimensional transparent glass using origami techniques. The question is: ‘how do you fold glass?’

28 New smart cement: more sustainable roads and cities

However infrastructure is built, it must be maintained and eventually renewed. Millions of tons of waste are generated every year and new cement has to be produced, which causes extra CO2 emissions. To prevent a corresponding amount of CO2 from being released as a result, these new cities and roads must be built with sustainable and smart concrete.

32 A new liquid crystal ink for 3D printing

Cholesteric liquid crystals, a man-made material with properties between liquids and solid crystals, can mimic the colours of butterfly wings. Liquid crystals are used in televisions and smartphones, but future applications for healthcare sensors or decorative lighting are difficult as the materials can’t be used in advanced, rapid production methods like 3D printing. The materials are not viscous enough to make stable, solid structures, and it’s difficult to align the molecules to produce specific colors. TU/eresearchers have solved these issues by developing a new light-reflective liquid crystal ink that can be used with existing 3D printing techniques. The new research has been published in the journal Advanced Materials.

Cover: 3D printed bridge by MX3D. Manufacturing robot in action (Photography: Olivier de Gruijter), page 18

INNOVATIVE MATERIALS 4 2021

NEWS

Photo: ETHZ

3D printed and unreinforced concrete bridge Countless structures around the world are made with reinforced concrete.

Although reinforced concrete has won its spurs as a construction material, there are environmental drawbacks. A lot of CO2 is released during the production of concrete as well as the steel for reinforcement.

The Block Research Group teamed up with the Computation and Design Group at Zaha Hadid Architects to build a 12-by-16-metre arched footbridge in a park in Venice - entirely without any reinforcement.

The concrete for the 3D printer was specially developed for this project by Holcim.

The bridge is made of 3D printed concrete elements, which are designed in such a way that there is no need for

2 | INNOVATIVE MATERIALS 4 2021

NEWS use and waste.

New is the type of 3D-printed concrete, which the researchers developed together with the company Incremental3D. The concrete is not layered horizontally in the usual way, but at certain angles, such that they are perpendicular to compressive forces. As a result, additional reinforcement or post-tensioning could be dispensed with. Because the construction does not require mortar, the blocks can be dis­­man­t­­led and the bridge can be rebuilt at a different location.

ETHZ>

Photo: : ETHZ/YouTube

reinforcement and no mortar to stick the individual parts together. Using digital techniques, a traditional vaulted arch construction was designed, which owes its stability to the shape of the elements.

They are shaped in such a way that the compressive forces are maximally dissi-

pated to the foundation. The dry-mounted construction is stable only because of its geometry.

The 3D concrete printing technology enabled the developers of the bridge to use material only where it is structurally necessary, resulting in minimal material

Video (ETHZ/YouTube)

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Bel ons op 026 3845600 of mail info@tcki.nl www.tcki.nl

3 | INNOVATIVE MATERIALS 4 2021

NEWS

Mycelium leather

Photo: VTT

Leather and synthetic leather production have a large negative environmental impact due to resource-intensive processes and hazardous chemicals used during production. The fashion industry is responsible for a full 10 % of global carbon emissions; with a carbon footprint estimated to be 130 millions tons annually.

Scientists of the Finnish VTT Research Institute demonstrated that VTT’s technology enables the continuous manufacturing of mycelium leather. With the process, fungal mycelium is processed in a bioreactor. The mycelium mass can then be casted continuously to produce a film with a continuous production of mycelium leather at 1 meter per minute.

Finally the sheet is dried resulting in a leather like material. The material is 100 % biobased.

The first product applications for the material could be accessories, footwear, and garments, for example. According to VTT the material has a leathery look and feel and can be as strong as animal leather. It also offers the possibility to be coloured and patterned, and it does not contain any backing or supporting materials.

Fungal mycelium is a bio-based raw material that can be sustainably proces-

4 | INNOVATIVE MATERIALS 4 2021

sed into leather-like materials. Until now, increasing the production volume with current methods has been challenging due to mycelium cultivation taking place in a planar two-dimensional form limited

Fungal mycelium is processed in a bioreactor

in size.

VTT’s patent-pending technology for producing mycelium leather alternative materials is based on growing mycelium in common bioreactors. The benefits of

NEWS manufacturing method are consistent quality, competitive production price, and reduced amounts of offcuts.

At the moment, the VTT team is exploring applications in the accessory, footwear, and garment segments. The researchers are now turning to improve tear strength and abrasion resistance by bio-based approaches.

VTT>

Photo: VTT

this approach are that liquid fermentation in bioreactors is easily scalable to commercial scales and similar fermentation technology is already widely used in the food, chemical, and pharma indus-

tries.

The film-making process developed by VTT enables continuous mycelium leather alternative production using VTT’s pilot equipment. The benefits of this

Video (VTT/YouTube)

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NEWS

Longest solar cycle path in the world opens Last summer, the longest solar cycle path in the world was opened at De Bilt.

It is a pilot project of the province of Utrecht in which the space is used twice: both for bicycles and for the generation of sustainable energy. If successful, the province wants to use solar cycle paths on a larger scale.

The SolaRoad solar cycle path consists of prefab concrete modules measuring 2.8 by 3.5 metres. These have a plastic, translucent top layer of approximately 0.5 cm thick. It is dirt-repellent and non-slip thanks to the transparent coating. Below the top layer, the silicon solar cells are placed between glass plates that protect them against mechanical stress, road salt and weather influences.

In mid-June 2021, contractor Strukton Civiel started the construction of the SolaRoad solar cycle path in Maartens-

6 | INNOVATIVE MATERIALS 4 2021

dijk. SolaRoad has previously been used in the province of Noord-Holland and, based on the results, has been further developed in collaboration with TNO and Strukton Prefab Beton. The new solar cycle path supplies the network with sustainable energy and is safe, comfortable and maintenance-friendly due to the use of new insights, materials and techniques.

The province of Utrecht wants to be energy neutral by 2040. The solar cycle path is a pilot project of the province of Utrecht in collaboration with Strukton Civiel.

The first SolaRoad cycle path was constructed in 2014 as a pilot in Krommenie along the N203 mororway. In the Twente municipality of Haaksbergen, a SolaRoad cycle path has been constructed in the green business park Stepelerveld. The electricity generated there is used for

public lighting and the LED screen on the business park. In Groningen, the elements have been used in a bench and electric bicycles and mobile telephones can be charged with the energy generated. The principle has also been applied across the border, such as in France.

More at Strukton (Dutch)> More about SolaRoad (English)>

Video: Strukton/YouTube

NEWS

Lignin coating for wood Researchers turn a non-toxic residue into wood coating that resists abrasion, stain, and sunlight.

Due to the global efforts to meet sustainability standards, many countries are currently looking to replace concrete with wood in buildings. But wood also has drawbacks. It is prone to degradation when exposed to sunlight and moisture. So protective coatings are needed to bring wood into wider use.

Researchers at Aalto University have used lignin, a natural polymer abundant in wood and other plant sources, to create a safe, low-cost and high-performing coating for use in construction.

Lignin is often regarded as a waste product of pulping and biorefinery processes. Each year, about 60 - 120 million tonnes of lignin is isolated worldwide, of which 98 percent is incinerated for energy recovery. Lignin has several beneficial properties; however, the poor solubility of most lignin types and the mediocre performance of lignin-based products have so far limited its commercial applications.

To address this issue, water-dispersible colloidal lignin particles (CLPs) and an epoxy compound, glycerol diglycidyl ether (GDE), were used to prepare multiprotective bio-based surface coatings.

That seems to have worked.

With the GDE/CLP ratios of 0.65 and 0.52 g/g, the cured CLP-GDE films proved to be highly resistant to abrasion and heat. When applied as a coating to wood substrates, even very thin (half the thickness of commercial coatings) pro-

Water-repellent wood coating protects against stains and sun induced colour changes while maintaining wood’s breathability and natural roughness (Photo: Aalto)

vided effective protection against water, stains, and sunlight.

According to the Aalto researchers, lignin shows great promise as a coating material, and has important advantages over the synthetic and biobased coatings

that are currently being used. It has excellent anti-corrosion, anti-bacterial, anti-icing and UV-shielding properties.

Future research will concentrate on developing characteristics like elasticity of the coating.

The study is published in ACS Applied Materials & Interfaces on 15 July 2021 titled ‘Colloidal Lignin Particles and Epoxies for Bio-Based, Durable, and Multiresistant Nanostructured Coatings.’

It’s online> Aalto>

7 | INNOVATIVE MATERIALS 4 2021

NEWS

Ready to install: the Alpet insulating web made of plastic. The greenish color of the filling material comes from the use of PET from recycled bottles (Photo: EMPA)

Alpet: insulating material made from recycled PET Insulating strips are an essential component for good thermal insulation in aluminium window profiles and facades.

In windows they act as thermal separators between the outside and the inside.

An important element that is becoming even more important with global warming and the need to reduce CO2-emissions. And although it has been around for more than four decades, the material is

Video

8 | INNOVATIVE MATERIALS 4 2021

in need of improvement.

For this reason, the Swiss research institute EMPA, together with Hochuli Advanced (a spin-off of the metal construction company Hochuli ), developed the new insulation material called Alpet.

It is a composite of glass fiber reinforced plastic containing a foam strip of polyethylene terephthalate - PET - from recycled PET bottles.

The insulating properties of Alpet are due to countless pores (with a diameter of less than 0.5 mm) in the PET material.

The thermal conductivity of the proto­ types is about 0.1 W/mK, which is according to EMPA much less (and therefore better) than a standard insulation strip made of conventionally used polymers, such as polyamide (about 0.25 W/mK).

Meanwhile Alpet has been tested by the specialized German IFT test institute in Rosenheim (Bavaria). The German ex-

perts not only repeated the Swiss tests, but also subjected the prototypes to fire and fracture tests and other stresses for example, to invisible micro-cracks after 1000 hours of storage in oil or slightly acid, or to strong stress in the transverse direction.

Compared to the high-end products which are already on the market, Hochuli estimates that the thermal insulation in, for example, a new office buildings, can be improved by up to twenty percent with Aplet. And because the new insulation strips are compatible with all existing common systems, existing solutions can be upgraded relatively easily.

EMPA>

NEWS

Electrifying cement with nanocarbon black Concrete is primarily used in construction applications. A multiyear effort by MIT Concrete Sustainability Hub (CSHub) researchers, in collaboration with the French National Center for Scientific Research (CNRS), has aimed to change that. Ultimately, the objective is to make concrete more sustainable by adding novel functionalities - electron conduction in particular. This would permit the use of concrete for a variety of new applications, ranging from self-heating to energy storage.

The research was recently published in ‘Physical review materials’ under the title ‘Electric energy dissipation and electric tortuosity in electron conductive cement-based materials.’

Their approach relies on the controlled introduction of highly conductive nanocarbon materials into the cement mixture. This could add an entirely new

dimension to what is already a popular construction material.

For their research, the team chose nanocarbon black - a cheap carbon material with excellent conductivity. Their conductivity predictions were confirmed. When only four percent carbon black was added, the material turned out to be conductive. They noticed that this current even could generate heat, coused by the co called Joule effect. Joule heating (or resistive heating or Ohmic heating) is the process by which the passage of an electric current through a conductor produces heat. It is caused by interactions between the moving electrons and atoms in the conductor.

They found that even a small voltage - 5 volts - could increase the surface temperatures of their samples (approximately 5 cm3 in size) up to 41 degrees Celsius.

This could be interesting for new, potential applications, like radiant indoor floor heating.

But there are also opportunities for nanocarbon cement outdoors, such as clearing snow from sidewalks or airport runways.

Before that happens, a series of technical problems must be solved. Without a way to align the nanoparticles in the cement in a functioning ‘circuit’ the conductivity would be impossible to exploit.

So the team focused on a trait known as tortuosity.

The path taken by electrons through the cement is tortuous and thus greater than the length of the cement sample.

The degree to which that path is longer is called the tortuosity.

Achieving the optimal tortuosity means balancing the quantity and dispersion of carbon. If the carbon is too heavily dispersed, carbon can lead to too high tortuosity. Similarly, without enough carbon in the sample, the tortuosity will be too great to form a direct, efficient wiring with high conductivity.

So even adding large amounts of carbon could prove counterproductive. It is there­fore essential to optimize the mixture exactly.

The goal of their recent paper was not just to prove that multifunctional cement was possible, but that it was also viable for mass production. By isolating and quantifying these mechanisms, the team hopes that multipurpose cement can eventually be implemented on a broad scale.

Two of their conductive cement samples (Photo: Andrew Logan)

More at MIT>

9 | INNOVATIVE MATERIALS 4 2021

NEWS

Fermentation composite cabinet (Photo: DITF)

Converting fermentation residues to furniture The Hallertau is the largest hop-growing area in Germany. When harvesting hop chaff is left over, which is converted into environmentally friendly bio-methane on site in a biogas plant. The residue left over from that fermentation process is used as fertilizer in agriculture because of its high nutrient content. But that application is seen as low-value and, moreover, nitrogen ends up in the soil in this way.

Researchers from the German Institute for Textile and Fiber Research Denkendorf (DITF), together with scientists from the University of Reutlingen, have found a way not to let those fermentation residues end up in the field, but to convert them into a material that can be used

10 | INNOVATIVE MATERIALS 4 2021

Residue from the fermentation process (Photo: DITF)

NEWS in industry. This material is a composite that can be used to produce laminates that can in turn be used to fabricate furniture.

First, the residue is washed, after which a non-woven mat is made. This is impregnated with a biobased resin system and finally compressed into a composite material. The material can be used in various ways as a (load-bearing) construction material. Meanwhile the team has fabricated a small square box of the material as a demonstration model.

According to DITF the project is an example of successful circular economy and value creation. Using biogas digestate as an industrial raw material is an environmentally-friendly alternative to their previous use as fertilizer, which increases nitrate pollution of the soil and is also significantly restricted by new regulations. Chemical additives are deliberately

Non-woven mat impregnated with a biobased resin (Photo: DITF)

avoided in the production process, and if offcuts from the textile industry are also used in the design of the furniture, this results not only in unusual designs

but also in further added value for the environment.

DITF>

‘Construction should focus on biobased materials’ Earlier this year, Rabobank published an article stating that building with biobased materials is necessary to achieve the Dutch government’s target of full circularity by 2050. Materials such as straw, flax and especially wood are often fully recyclable or compostable and absorb CO2 from the atmosphere and store it.

One cubic meter of wood compensates for approximately 1 tonne of CO2, (equivalent to approximately 5,000 car kilometres.) In addition, wood as a building material has a number of constructive and technical advantages.

According to Rabobank, the most important advantage is the contribution that biobased materials can make to more CO2-neutral construction production and thus to the total climate and circular construction objectives of the Netherlands. This also makes biobased construction attractive in the short term, because it can be a solution for areas

where construction is currently prohibited due to nitrogen regulations. In addition, more production forestry could be a financially attractive prospect for some agricultural lands and companies in our country. In this context, Rabobank sees

excellent options for more own forestry in potentially vacant agricultural acreage (agroforestry).

More at Rabobank (Dutch)>

11 | INNOVATIVE MATERIALS 4 2021

NEWS

Bioactive paper coatings to replace plastic for packaging foods The amount of plastic waste increases every year. Some of this waste is due to plastic packaging used to protect food.

As part of the ‘BioActiveMaterials’ project, researchers at the Fraunhofer-Gesellschaft have developed an eco-friendly coating for paper packaging.

The vast majority of sausage, cheese, meat and fish is pre-packed. Fresh fruit, salad and vegetables too often come in plastic packaging. These plastic packa­ ging is often based on mineral oil and when it ends up in the environment, it breaks down into microplastics, which

12 | INNOVATIVE MATERIALS 4 2021

eventually make their way into the food chain.

The Fraunhofer Institute for Process Engineering and Packaging IVV and the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB have now presented an innovative and sustainable solution for food packaging. Just as with conventional packaging, it keeps the food fresher for longer. The new packaging, though, involves no plastic whatsoever. After use, it can be recycled without a problem.

In the ‘BioActiveMaterials’ project, the

researchers use paper as the base material for producing typical and functional packaging materials: resealable bags or wrapping paper. The paper is provided with a special coating using standard processes. The researchers make this coating from proteins and waxes with biobased additives. The special formulation of this coating, which offers long-term stability, performs several functions at the same time. First, the proteins act as an oxygen barrier layer while the waxes form a water vapor barrier, preventing fruit, for example, from drying out quickly. Second, the biobased

NEWS additives have an antioxidative and antimicrobial effect. This stops meat and fish spoiling as quickly. Overall, the food has a much longer shelf life. The proteins in the coating also play specific roles. They prevent mineral oil permeation from the paper to the food. Recovered paper in particular contains residues of mineral oil-containing printer’s ink.

According to the Fraunhofer researchers, the coated papers they have developed are an excellent alternative to the packaging currently used for food. Consumers can store and handle the paper­ packed foods in exactly the same way as the food packed in plastic today.

In the coating process, the paper is guided over rolls and provided with the ‘BioActive Materials’. These are supplied in the form of an aqueous dispersion (Photo: Fraunhofer)

When selecting the raw materials, the team chose natural substances approved for use in the food industry. For the protein element, for example, they experimented with rapeseed, lupins, whey or sunflowers. Turning to the waxes, the researchers went for beeswax and wax produced from the candelilla bush native to northern Mexico and from the Brazilian carnauba palm. These products are biodegradable, approved for food contact and readily available on the market.

According to Fraunhofer, the skill is in the mixing ratio and the sequence in which the individual substances are added. The flexibility with the ratio when mixing the different substances also enabled the researchers to optimize the coating for specific applications. Packaging for meat, for instance, containing more antioxidants, could have a particularly strong antimicrobial and antioxidative effect, whereas a wax coating protects salad packed in a pouch especially well against drying out.

The bioactive coating can be used for cardboard as well as paper. And printing on the packaging is no problem either.

A producer could print on their logo or the nutrition information required under food law.

Fraunhofer>

A resealable bag made of paper with the coating on the inside. After use, the packaging is placed in the waste paper recycling bin with the bioactive materials (Foto: Fraunhofer)

13 | INNOVATIVE MATERIALS 4 2021

MAKE IT MATTER

MAKE IT MATTER MAKE IT MATTER is compiled in collaboration with MaterialDistrict (MaterialDistrict.com). In this section new, and/or interesting developments and innovative materials are highlighted.

Turning polluted soil into bricks Dutch designer Emy Bensorp, with her startup Claybens, developed a method to turn PFAS polluted clay soil into clean ceramic materials and products like bricks. In 2019, political attention for PFAS shut down the complete building sector of the Netherlands, as Dutch soil contains PFAS in many areas.

Bensorp designed a solution for the PFAS problem, by using contaminated clay to make bricks. Bricks have to be fired, and PFAS is destroyed at high temperatures.

More at MaterialDistrict>

Paint made from waste concrete Designer Kukbong Kim developed a paint called Celour made from waste concrete powder, leftover from recycling concrete, which actively captures and stores CO2 by mineral carbonation.

This is a coercion in which the CaO (calcium oxide) component inside the powder reacts with CO2 to form CaCO3 (calcium carbonate). So by applying Celour paint, less cement powder disappears into the landfill and CO2 is bound from the atmos­ phere.

More at MaterialDistrict>

Ultra water-permeable pavement Start-up Aquipor designed a pavement material with submicron-sized pores that allows water to pass through, but everything else to stay on the surface. The surface technology has the strength and durability of traditional concrete, but features water flow rates that allow large volumes of rainfall to pass through it naturally. There are other permeable pavement solutions, but these often feature large holes, which can get clogged.

More at MaterialDistrict>

14 | INNOVATIVE MATERIALS 4 2021

MAKE IT MATTER Acoustic design mycelium panels Architectural firm Arup and Italian biodesign company Mogu teamed up to design what is said to be the world’s first mycelium acoustic panel system, called Foresta. The Foresta panel system consists of a modular framework so it can be adapted according to the need of the interior. Each module is grown by mushroom cultures on a substrate of agricultural waste materials, such as hemp chives and textile residue.

More at MaterialDistrict>

A tower made of 99% reclaimed materials The Boomtoren, the newest addition to the Hof van Cartesius, a circular workspace for creative and sustainable entrepreneurs in Utrecht, the Netherlands, is a tower made of 99% reclaimed materials, including recycled CLT and windows from demolished Dudok buildings.

More at MaterialDistrict>

RiBoard RiBoard is manufactured from recycled mineral fibres with cementitious binders. It offers good acoustic absorption and is also completely fire resistant. Its components are environmentally friendly with the main ingredient being a 100% recycled mineral fibre material. RiBoard readily accepts varied surfaces such as HPL or wood veneer. It can also be custom dyed to the colour choice of the customer.

More at MaterialDistrict>

SuprAnodic Collection Chemical anodization has become a popular finish for aluminum building components. The popular finish however has certain drawbacks, like colour consistency between different batches and a limitation of the choice of colours. The SuprAnodic collection is a super durable, long lasting powder coating. It has been specially developed for aluminium and steel architectural components, such as window frames, façades, cladding and doors. The collection consists of twenty-two colours with an anodized look with all the benefits of a powder coating in super durable quality.

More at MaterialDistrict>

15 | INNOVATIVE MATERIALS 4 2021

INNOVATIVE MATERIALS

15 July 2021. Queen Máxima opens the world’s first 3D-printed steel bridge in Amsterdam (Photo: MX3D/Adriaan de Groot))

World first:

3D printed steel bridge opens On 15 July, Her Majesty Queen Máxima opened the world’s first 3D-printed steel bridge in Amsterdam. The bridge was manufactured by the Amsterdam scale-up MX3D and is placed on the Oudezijds Achterburgwal in Amsterdam. The bridge is a prize-winning design by Joris Laarman Lab and the result of a collaboration between, among others, MX3D, software company Autodesk, chief engineer Arup, steel concern ArcelorMittal, the Municipality of Amsterdam and the University of Twente. Over the next two years, this pedestrian bridge will replace the old bridge that will be externally restored.

According to MX3D this project has shown that it is possible to print large sizes in metal. With this new technology metal structures can be produced, without wasting material and flexible in shape and style. In the future, it will be possible to produce with less material and in a completely new design language.

Laarman’s futuristic design is 12.2 metres long, 6.3 metres wide and weighs 6,000 kilos. MX3D made this design possible, with Arup as chief engineer, by turning welding robots with intelligent software into industrial 3D printers.

16 | INNOVATIVE MATERIALS 4 2021

Layer by layer, they created the organic shapes. The bridge, which remains the property of MX3D, was extensively tested by Imperial College London, with the help of the University of Twente, before being installed.

To ensure the safe construction of the bridge, Imperial College London conducted research into its strength and structure.

The test took place in September 2019 at the University of Twente. There, the full load-bearing capacity of the bridge was tested to ensure safety and functionality. In addition to the design, the

monitoring of the bridge is also innovative. The bridge is equipped with smart sensors to collect data for maintenance.

For this reason, the University of Twente, together with MX3D, Autodesk and Arup, designed, developed and tested a permanent sensor network and eventually installed it on the bridge.

Besides the design, the monitoring of the bridge is also innovative. The bridge is equipped with smart sensors to collect data for maintenance. Software company Autodesk and The Alan Turing Institute have created a so-called Digital Twin of the bridge. This allows the safety

INNOVATIVE MATERIALS

Manufacturing robot in action at MX3D (Photo: MX3D/Olivier de Gruijter)

status to be monitored in real time, including the simulation with different conditions and loads. With the data, the municipality can also measure traffic flows across the bridge and the level of congestion in the area.

In addition, Amsterdam Institute for Advanced Metropolitan Solutions (AMS Institute), in cooperation with TU Delft, University of Twente and the municipality of Amsterdam, among others, is conducting research into the ethical consequences and regulation of smart infrastructure in the city. Questions such as: ‘What do we as citizens actually want to be measured?’ and ‘Who owns the collected data?’ and ‘Do we really want a city full of sensors? The bridge will become a true ‘Living Lab’.

Tree years ago, the bridge won the Public Award during the Dutch Design Week 2018.

UTwente> MX3D> Joris Laarman>

Video (MX3D/YouTube

Above: The steel 3D-printed bridge during the Dutch Design Week in 2018 Below: Placement of the bridge Oudezijds Voorburgwal (Photo’s: Adriaan de Groot)

The MX3D project was made possible thanks to the close cooperation with partners: Autodesk, Heijmans, Joris Laarman Lab and ArcelorMittal and the support of Lead Structural Engineer Arup, The Alan Turing Institute Data Centric Engineering Programme, Lloyd’s Register Foundation, Air Liquide, ABB Robotics and Lenovo. Major contributors included: Force Technologies, HBM, Oerlikon, Faro Technologies, STV, Oerlikon Welding, MousBV and Plymovent. Public partners: Delft University of Technology, Imperial College London, University of Twente, Amsterdam Institute for Advanced Metropolitan Solutions (AMS Institute) and the municipality of Amsterdam.

17 | INNOVATIVE MATERIALS 4 2021

INNOVATIVE MATERIALS

Illustration: WFBR

New generation of biobased polyesters for sustainable products To enable the introduction of biobased polyesters into the high-performance applications sector, such as automotive and electronics, Wageningen Food & Biobased Research is developing a new generation of Biobased polymers using the Isoidide molecule.

Biobased products are gradually claiming their share in everyday products like packaging already, and now WUR scientists want to develop polymers for the high-performance market as well.

Using Archer Daniels Midland’s rigid starch-based molecule called isoidide, they are developing a new generation of polymer materials that can be used not only in BPA(Bisphenol A)-free packaging but also in engineering applications such as automotive and electronics.

These biobased, yet strong and thermally resistant materials are versatile. This is also apparent from the projects in which Wageningen Food & Biobased Research collaborates with its industrial partners.

Refresco for instance is interested to explore the potential of HIPPSTAR materials for bottles; Beckers will use them as

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Isoidide belongs to the dianhydrohexitols, molecules that are derived from renewable resources from cereal-based polysaccharides. In the field of polymeric materials, these diols are essentially employed to synthesize or modify polycondensates. Their attractive features as monomers are linked to their rigidity, chirality, non-toxicity, and the fact that they are not derived from petroleum.

The raw material isoidide is of interest for a wide range of polyesters. It is a symmetrical and thermally stable monomer obtainable from sugar. This is partly why it is an interesting building block for biobased products. Polymers based on isoidide are useful for packaging or building materials, but also for other applications, such as applications in the electronics industry and the automotive industry.

INNOVATIVE MATERIALS metal coatings, while HollandColours will use them in their colorants formulations.

Working together with important industrial partners is the best way to develop polymers that meet the requirements and standards of the market.

Using agricultural side streams and surpluses of biomass production, instead of depleting and polluting fossil-feedstocks while enjoying the extraordinary quality of modern products is the optimal sustainable solution to contribute to the balance of nature and humans coexistence.

Using biobased polymers in durable products contributes to the circular biobased economy by reducing CO2 footprint of the materials. High demands of modern society versus Planet Earth’s desperate need for serenity are connected in the promising HIPPSTAR project.

Wageningen University & Research (WUR)> Archer Daniels Midland (ADM)> Beckers Industrial Coatings> Holland Colours Apeldoorn> Refresco>

HIPPSTAR: High performance polymers based on starch In WFBR’s long-standing collaboration with Archer Daniels Midland (ADM), precompetitive technologies were developed in various projects, including projects co-funded by the Dutch Topsector AgriFood. In an earlier project , WFBR and ADM have developed generic technology for the production of high performance isoidide (a novel building block derived from starch) based polyesters. Owing to their high thermo-mechanical properties, isoidide polyesters showed a high potential to be used in applications beyond packaging.

The objective of this project is to synthesize a broader family of isoidide-containing polymers and obtain extensive scientific insights into their mechanical, gas barrier, fibre and film forming properties. In addition, their industrially relevant application potential in applications like (food) packaging and coatings, textile fibres and industrial coatings will be explored in collaboration with four industrial partners: ADM, Beckers Industrial Coatings, Holland Colours Apeldoorn and Refresco.

HIPPIE: Ontwikkeling van high performance-polymeren op basis van isoidide (Dutch)> Science direct: ‘Polymers from renewable 1,4:3,6-dianhydrohexitols (isosorbide, isomannide and isoidide): A review’ (2010)>

4 + 5 nov 2021 Messe Nürnberg ∙ NCC West

4 -7 nov 2021

International Trade Fair • Ideas • Inventions • New Products Messe Nürnberg · Hall 12

6 +7 nov 2021

Trade Fair Ticket €10,-

instead of

€12,-

Promocode: IFNL21IE iena.de/ticket

Partner:

www.iena.de 19 | INNOVATIVE MATERIALS 4 2021

INNOVATIVE MATERIALS

Stand-up paddle board made from renewable lightweight materials Wood fibres (Photo: Fraunhofer)

Conventional surfboards are made of petroleum-based materials such as epoxy resin and polyurethane. Researchers at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut, WKI, want to replace plastic boards with sustainable ones by developing a stand-up paddle board that is made from one hundred percent renewable raw materials.

The ecological lightweight material can be used in many ways, such as in the construction of buildings, cars and ships.

In the so-called ecoSUP project, the Fraunhover scientists are aiming for the development of a stand-up paddle board that is made from 100 percent renewable raw materials and which is also particularly strong and durable. The project is funded by the German Federal Ministry of Education and Research (BMBF). The Fraunhofer Center for International Management and Knowledge Economy IMW is accompanying the research work, with TU Braunschweig acting as project partner.

The standard plates from which conventional paddle boards are made, consist of a polystyrene core, reinforced with fiberglass and sealed with an epoxy resin. Instead, the Fraunhofer team used

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Textile made of flax fibers inserted into the board as reinforcement (Photo: Fraunhofer)

INNOVATIVE MATERIALS recycled balsa wood for the core. This has a very low density and yet mechanically stressable. For that reason, it has been used in large quantities in wind turbines for many years. But wind turbines are also being dismantled and scrapped - 6000 in 2020 alone - and a large part of the waste material is incinerated, including the balsa components.

Recovering the balsa wood from the rotor blade is not easy. Balsa is firmly bonded to the glass-fiber reinforced plastic (GFRP) of the outer shell. Franhofer WKI developed (and patented) a method in which the wood is separated from the composite material in an impact mill.

The density differences can be used to split the mixed-material structures into their individual components using a wind sifter. The balsa wood fibers, which are available as chips and fragments, are then finely ground. In this process, the wood particles are suspended to form

a kind of batter and processed into a light yet firm and stable wood foam. The addition of adhesive is not required. The density and strength of the foam can be adjusted.

Since the entire sandwich material used in conventional paddle boards is to be completely replaced, the shell of the ecological board is also made from one hundred percent bio-based polymer. It is reinforced with flax fibers.

Initially, the researchers are focusing on stand-up paddle boards. However, the hybrid material is also suitable for all other boards, such as skateboards and even as a facade element in the thermal insulation of buildings.

Fraunhofer>

De Bond voor Materialenkennis (BvM) is een netwerk van experts op het gebied van materiaaltechnologie. Leden zijn onderzoekers en technici bij universiteiten, hogescholen, onderzoeksinstituten en de industrie. Het doel van de BvM is om kennis van de verwerking en toepassing van materialen te verspreiden, binnen en buiten het materialenveld.

De BvM initieert symposia, cursussen, technisch-wetenschappelijke publicaties, onderzoeksactiviteiten en bevordert de educatie in materialen.

De totale aangeboden technologische kennis van ieder deelgebied metalen, kunststoffen, keramiek, biogebaseerde materialen, lasertechnologie, verbindingen, verftechnologie, reologie, tribologie, corrosie, warmtebehandelingstechniek, duurzaamheid en betrouwbaarheid - maakt de BvM een krachtige beroepsorganisatie in Nederland en België.

Voordelen van het lidmaatschap van de BvM:  Gratis studentenlidmaatschap: Vertel het verder!  BvM-leden genieten van het FEMS- en het EFC-lidmaatschap van de BvM FEMS is de Federation of European Materials Societies EFC is de European Federation of Corrosion  Korting op activiteiten van de BvM  Toegang tot een groot materialennetwerk

Kijk voor meer informatie en contact op de nieuwe website van de Bond voor Materialenkennis: https://www.bondvoormaterialenkennis.nl/

21 | INNOVATIVE MATERIALS 4 2021

INNOVATIVE MATERIALS

Auxetic concrete: energy from the waves When waves batter the coast, energy is generated. Researchers Branko Šavija and Yading Xu from TU Delft want to capture that by using a special type of concrete to create an alternative energy source. For several years, Šavija has been working at the Department of Materials Science and Engineering at TU Delft on materials that behave ‘unexpectedly’, like auxetic concrete, a flexible concrete with special propertie. When loaded, it contracts, but if the load disappears, it expands like a sponge. Normal concrete also moves but not as much. This new concrete contains holes, as a result of which it is less strong but more flexible.

One possible application that the re­ searchers see is using concrete in coastal protection. Breakwaters consist of large pieces of concrete. The vibrations that arise in the concrete when the waves hit it can be converted into electricity. And there are techniques available to convert such a movement into energy. As the

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Netherlands has 450 km of coastline, the researchers see a lot of potential in this plan. Šavija and his fellow researcher Yading Xu submitted a proposal to the NWO funding instrument Open Mind last year. In November 2020, during the online edition of innovation festival TEKNOWLOGY, they received a grant of

50,000 euros. With that, they have a year to test their plan. According to the jury, it was a ‘completely original idea to explore an interesting new source of energy’.

In their lab, Šavija and Xu are currently working on linking piezoelectric polymer films to the concrete. This soft and

INNOVATIVE MATERIALS flexible film is capable of converting the movement from the concrete into electronic resistance.

Meanwhile, the ideas have also aroused attention outside the TU. They have now submitted a proposal for a European grant that has already yielded a number of contacts for the future, even if the proposal is rejected. For instance, contact has been made with an Italian university that is working on energy generation through human movements, for example through sensors in shoes.

The researchers expect that if they are able to show a proof of concept at the end of the current project, it will then be easier to approach commercial parties who might be interested in supporting this type of research too.

Text is based on the article ‘Obtaining energy from concrete’ CiTG TU Delft.

Demonstration of power generation with auxetic concrete (Photo: TU Delft)

Auxetics

Video: TUD/YouTube Open Mind 2020 contestants - Auxetic concrete energy harvester

Auxetic materials (auxetics) are structures or materials that have a negative so-called Poisson’s ratio1. When stretched, they become thicker perpendicular to the applied force. This occurs due to their particular internal structure and the way this deforms when the sample is uniaxially loaded. Such materials and structures are expected to have mechanical properties such as high energy absorption and fracture resistance.

1

Poisson’s ratio is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading.

More about Auxetics>

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RESEARCH

Ground breaking method for ReLiB-battery recycling Researchers at the University of Leicester have developed a new method to recycle electric vehicle batteries using a totally new approach. This work was done by a Faraday Institution project on the recycling of lithium-ion batteries (ReLiB) led by Professor Andy Abbott at the University of Leicester.

The Faraday Institute was founded in 2017 and has since operated as the UK’s national research institute in battery science and technology. The Institute is mainly concerned with commercially relevant research needed for future battery development to power the transport and energy revolution for the UK. The Faraday Institute research is being conducted by or in collaboration with British universities, Leicester University in this case.

With current recycling methods, discarded lithium-ion batteries are typically

Photo: Faraday Institution, Leicester University

processed in a shredder or high-temperature reactor. Subsequently, a number of physical and chemical processes are required to recover the usable materials;

a route that is very energy-intensive and inefficient.

Abbott and his colleagues developed a new method, which uses high-power ultrasound. First, the batteries are disassembled and then the material is exposed to ultrasonic waves, causing cavitation and delamination of the various materials. The aluminium or copper electrodes remain behind. The process proved extremely effective in removing graphite and lithium-nickel-manganes­ cobalt oxides, in short NMC. The research team further tested the technology on the four most common battery types and found that it performs with the same efficiency in each case.

The results were published in Green Chemistry titled ‘ Lithium ion battery recycling using high-intensity ultrasonication’. It’s online> Leicester University>

Diagram showing the ultrasonic process which assists in the delamination of lithium-ion batteries

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INNOVATIVE MATERIALS

Illustration based on picture from Nature Communications

Complex glass geometric structures

Origami glass Glass is a great material in many ways, but the detailed design of glass products is not easy.

This has to do with the brittle properties of the material and the high temperatures at which the (conventional) molding processes work. In recent years, research into the use of silica-polymer composites as a prepolymer for glass production has shown that this technique offers perspectives for making complex geometric shape structures of glass, but this technique still has drawbacks. The same goes for 3D printing glass. Researchers from China’s Zhejiang University have now developed a method that makes it possible to create three-dimensional transparent glass using origami techniques. The question is: ‘how to fold glass?’

Glass is indispensable in many applications, from tableware to architectural constructions and telephones to works of art. In fact, glass is indispensable in many applications because of typical properties such as optical transparency, wear resistance and thermal and chemical stability.

Still, processing glass remains difficult, especially when it comes to complex geometries. Processing options are often limited compared to metal and polymers. This is due to the brittle nature of the material and the need that is often present to achieve full transparency.

3D printing

Conventional glass shaping processes operate under challenging conditions such as high temperature or chemical etching. Although sol-gel techniques make it possible to produce glass shapes under milder conditions, the geometric complexity is limited by the casting technique.

Another solution could be to use silicapolymer composites as a precursor for glass making, which opens the way to low temperature casting. The material can then be machined and sintered into the final 3D glass shape.

Finally - without the use of casting - such precursor composites (prepolymers)

glass also can be be shaped with a 3D printer. Universities and research institutes all over the world are looking for new processes when it comes to 3D printing of glass and although interesting results have been achieved, apparently no breakthrough has been forced yet (see box on following pages).

Origami

Researchers at Zhejiang University in Hangzhou, China, have now come up with something different. They developed a method that makes it possible to make three-dimensional transparent glass using origami techniques.

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INNOVATIVE MATERIALS Origami is the art of folding, once invented in China, but perfected over centuries in Japan. The trick of origami is to convert a flat sheet - originally paper into a three-dimensional geometry. Modern origami techniques can be used to create extremely complex shapes, which is exactly what the Zhejiang researchers had in mind.

Glass cannot be folded because of its brittle properties. The researchers now say they have found a solution for exactly that problem. It turns out that it is possible to compose the prepolymer in such a way that mecha­nisms are Left: a Schematic illustration of the fabrication process. b Two mechanisms for permanent deformation via plasticity. c Dynamic polymer ester network with dangling hydroxyl groups. d Photographic image of a 3D transparent glass feather. Scale bar: 1 cm. e Demonstration of the high thermal resistance at 600 °C. Scale bar: 1 cm (Illustration from Nature Communications)

3D printing glass All over the world, research is being done into the design of glass by 3D printing (Additive Manufacturig, AM). Two commonly used AM methods are in the spotlight: Selective Laser Sintering (SLS)

and Fused Filament Fabrication (FFF, also known as Fused Filament Fabrication).

In SLS, a powder is melted/sintered layer after layer into a solid product using a laser. In the case of FFF, a die extruder

applies molten material layer by layer.

Because the liquid material solidifies after each layer has been applied, the desired shape can thus be built up.

The problem with both techniques is that they depend on increasing the temperature to just below or above the melting point of the starting material.

Glass requires temperatures of over a thousand degrees Celsius.

The first studies date from around 2015.

In 2015, the Israeli company Micron3DP developed a system for 3D printing molten glass, specifically soda lime and borosilicate. That same year, the Mediated Matter group of the Massachusetts Institute of Technology and MIT Glass Lab introduced its G3DP (Glass 3D Printing) platform, a 3D printer specifically designed for glass processing. In 2017, MIT presented 3D-printed glass columns made with the G3DP2 platform during Mila Design Week: a further developed G3DP printer, which according to MIT is suitable for industrial production.

(Innovative Materials 2019 volume 1).

3D printed glass columns by the Mediated Matter-groep, MIT (Foto: MIT)

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Shortly before that, researchers from the Karlsruhe Institute of Technology (KIT)

INNOVATIVE MATERIALS introduced into the material, as a result of which the material can actually be folded initially.

They made a composite sheet by curing a liquid prepolymer filled with silica nanoparticles. The researchers then folded the material into various geometric figures using manual origami techniques.

By subjecting the material to a pyrolysis and sintering process, it is converted into transparent three-dimensional glass. In this way they managed to create more or less complex shapes, including a crane, vase and flower.

Although they folded the composite sheets by hand in this study, the researchers expect that the process could be automated and ultimately suitable for large-scale production.

The article ‘Transparent origami glass‘ was published in Nature Communications on 12 July 2021. It is online>

presented a completely new 3D printing method for glass. The method made use of stereolithography, in which a laser beam was applied layer by layer to the surface of a liquid material (usually a polymer, but in the case of KIT a mixture of a liquid polymer and nanoparticles of extremely pure quartz glass). Hardening occurs where the laser beam hits the liquid. The material which remained liquid, was then washed in a solvent bath, leaving only the desired cured structure.

The polymer still enclosed in this glass structure was then fired by heating. The research was published in Nature (April 2017) under the title ‘Three-dimensional Printing of Transparent Fused Silica Glass.’It’s online> Earlier this year, the OSA Optical Society reported the development of yet another method called ‘two-photon polymerization.’ The process was developed by researchers at the Fresnel Institute and the École Centrale de Marseille in France, the École Centrale and the University of Lorraine. Their results were published in Optics Letters showing the use of two-photon polymerization to 3D printing glass.

Example of the folding process. The black lines, red dashed lines, and blue dashed lines represent cutting, mountain folding, and valley folding, respectively. All scale bars are 1 cm. Credit: Xu et al.

(Illustration from Nature Communications)

The method is based on so-called multiphoton polymerization, which ensures that the polymerization takes place only and exactly at the laser focal point.

By sending the laser - or rather the laser focal point - through a medium through a certain pattern, an object can be created. The researchers used a mixture with a photochemical initiator, a resin and a high concentration of silica nanoparticles

as a medium. The high viscosity of this mixture makes it possible to form a 3D part with a double laser beam. The team managed to create several glass mini objects, including an Eiffel Tower and a bicycle.

More at OSA>

The new approach can be used to make a variety of complex objects such as the bicycle shown here (Photo: Laurent Gallais, The Fresnel Institute en Ecole Centrale Marseille)

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RESEARCH

Smart cement: more durable roads and cities However it is built, it must be maintained and eventually renewed. Millions of tons of waste are released every year and new cement has to be produced, which causes extra CO2 emissions. In addition, the UN expects that by 2050 two-thirds of the world’s population will live in cities, which means that a huge amount of (concrete) buildings must have been built by then. To prevent a corresponding amount of CO2 -emissions as a result, these new cities and roads must be built with sustainable and smart concrete.

Engineers tackling this issue with smart materials typically enhance the function of materials by increasing the amount of carbon, but doing so makes materials lose some mechanical performance. By introducing nanoparticles into ordinary cement, Northwestern University researchers have formed a smarter, more durable and highly functional cement.

Cement is the most widely consumed material globally, with the cement industry accounting for 8% of human-caused greenhouse gas emissions. Aiming for

28 | INNOVATIVE MATERIALS 4 2021

cement composites with a reduced carbon footprint, the Northwestern Research team, lead by environmental engineering professor Ange-Therese Akono, investigated the potential of nanomaterials to improve mechanical characteristics. It is believed that nanomaterials reduce the carbon footprint of cement composites, but until now, little was known about its impact on fracture behaviour.

An important question was to increase the fraction of carbon-based nanoma-

terials within cement matrices while controlling the microstructure and enhancing the mechanical performance. Specifically, the team looked at the fracture response of Portland cement reinforced with one- and two-dimensional carbon-based nanomaterials, such as carbon nanofibres, multiwalled carbon nanotubes, helical carbon nanotubes and graphene oxide nanoplatelets.

Nanomaterials are shown to bridge nanoscale air voids, leading to pore refinement, and a decrease in the porosity and the water absorption. An

RESEARCH

Ange-Therese Akono holds a sample of smart cement (Photo: Northwestern University)

improvement in fracture toughness is observed in cement nanocomposites, with a positive correlation between the fracture toughness and the mass fraction of nanofiller for graphene-reinforced cement. Thus, this study illustrates the

potential of nanomaterials to toughen cement while improving the microstructure and water resistance properties.

More at Northwestern>

The study, ‘Fracture toughness of one- and two-dimensional nanoreinforced cement via scratch testing,’ was published June 21 in the journal Philosophical Transactions of the Royal Society A. It is online>

A week of immersion in the world of 3D manufacturing!

December 6 to 10 2021, International multi-event – Benelux region

The International multi-event - 3D Delta Week - will be orga­ nized from 6 - 10 December 2021. The 3D Delta Week will create value for users and providers along the 3D Manufacturing Value Chain. It will be the 3D manufacturing meeting point for expert and layman, inside or outside the Benelux region.

The 3D Delta week is already gathering a dozen of renown events and will continue growing as the place-to-be, with activities aimed at specific sectors, at R&D and industry, at users and suppliers. The scheduling of events will allow participants to easily move from one activity to another.

The Benelux area (the Delta) is a top region in terms of 3D

production, with a myriad of academic and applied research centres, a particularly high number of 3D-printers and numerous promising start-ups and established enterprises.

On the user side, the region boasts a multitude of application areas - all in all, an extremely versatile and high-quality ecosystem. Now, the appropriate podium has been created to bring this leading 3D production region to the fore.

The 3D Delta Week is an initiative initially set up by Brainport Eindhoven, Flam3D, Jakajima and Mikrocentrum. www.3ddeltaweek.com

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RESEARCH

Metallic wood 2.0

also unique optical properties, allowing the material to potentially be used for sensors.

However, there is a problem. Until now, it was impossible to produce the material in a usable size due to ‘reverse cracking’ during synthesis.

An inverted crack, by contrast, is an excess of atoms; in the case of metallic wood, inverted cracks consist of extra nickel that fills in the nanopores critical to its unique properties.

This strip of metallic wood, about an inch long and one-third inch wide, is thinner than household aluminum foil but is supporting more than 50 times its own weight without buckling. If the weight were suspended from it, the same strip could support more than six pounds without breaking (University of Pennsylvania’s School of Engineering)

For the past three years, engineers at the University of Pennsylvania’s School of Engineering and Applied Science have been developing a type of material called ‘metallic wood.’

As with wood, metallic wood is full of

regularly spaced cell-sized pores that radically decrease its density without compromising the strength of the material.

The precise spacing of these gaps not only gives metallic wood the strength of titanium at a fraction of the weight, but

These inverted cracks stem from the way that metallic wood is made. It starts as a template of nanoscale spheres, stacked on top of one another. When nickel is deposited through the template, it forms metallic wood’s lattice structure around the spheres, which can then be dissolved away to leave its signature pores.

However, if there are any places where the spheres’ regular stacking pattern is disrupted, by cracks for instance, the nickel will fill those gaps, producing an inverted crack when the template is removed.

In the aqueous environment in which the process took place, the surface forces of water flowing are so strong that they drive the particles apart and form cracks. These cracks are very difficult to prevent, so the scientists developed a new strategy that allows them to self-assemble the particles while keeping the template wet. This prevents the films from cracking, but because the particles are wet, we have to lock them in place using electrostatic forces so that we can fill them with metal.

According to Penn the new manufacturing approach makes it possible to create larger, more consistent strips of metal wood. According to Peen, this new opens the way to make porous metals that are three times stronger than previous porous metals at similar relative density and 1,000 times larger than other nanolattices which can by used as membranes to separate biomaterials in cancer diagnostics, protective coatings and flexible sensors.

More at Penn>

Nanoscale pores are the key to metallic wood’s properties, but if there is a crack in the template before nickel is added, it will become an ‘inverted crack’ - a seam of solid nickel - when the template is removed. The researchers’ technique allows for crack-free regions that are 20,000 times larger than previously possible (Illustration: Penn)

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RESEARCH

From left to right, foam materials consisting of whey, polyurethane, polystyrene, polyethylene and polystyrene. The top row represents unexposed materials and the bottom row represents the materials exposed to 150 °C air for one month

Milk protein plastic foam Researchers at KTH Royal Institute of Technology deve­loped a new high-performance plastic foam from whey proteins that can withstand extreme heat better than many common petroleum based thermoplastics. The new material is based on protein nanofibrils, (PNFs), which are produced from hydro­lyzed whey proteins - a product from cheese-processing - under specific temperature and pH conditions.

The results were reported earlier this year in Advanced Sustainable Systems, titled ‘High-Temperature and Chemically Resistant Foams from Sustainable Nanostructured Protein’.

It is online>

In tests the foams improved with aging which polymerized the protein, creating new covalent bonds that stabilized the foams.

After one month of exposure to a temperature of 150 °C, the material became stiffer, tougher and stronger.

Despite proteins are often water-soluble, the material proved to be water-resistant after the aging process. The foam also resisted even more aggressive substances that normally decompose or dissolve proteins. The crosslinking mechanism also made the foam unaffected by diesel fuel or hot oil.

The material also showed better fire resistance than commonly used polyurethane thermoset.

Potential applications include providing support for catalytic metals that operate at higher temperatures, such as platinum catalysts for automobiles. The material could conceivably work as a fuel filter, too. Other possibilities are to use it as packaging foam and in applications for sound and thermal insulation where higher temperatures may occur and where there is a risk of an aggressive environment.

More at KTH>

SEM images of aged a) PNF-40, b) PNF-40-gly-33 foams (Picture from article)

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RESEARCH

A new liquid crystal ink for 3D printing

Cholesteric liquid crystals, a man-made material with properties between liquids and solid crystals, can mimic the colours of butterfly wings. Liquid crystals are used in televisions and smartphones, but future applications for healthcare sensors or decorative lighting are difficult as the materials can’t be used in advanced, rapid production methods like 3D printing.

The materials are not viscous enough to make stable, solid structures, and it’s difficult to align the molecules to produce specific colors. TU/e researchers have solved these issues by developing a new light-reflective liquid crystal ink that can be used with existing 3D printing techniques. The new research has been published in the journal Advanced Materials.

In nature, iridescent materials, which exhibit a colour change when viewed from different angles, can be found in butterfly wings and in nacre (or mother of pearl) in the inner shell of mollusks.

A man-made version of these natural materials is cholesteric liquid crystal, which has already been used as ‘smart’ materials in light reflectors, switchable windows, and tun-able solar energy collectors.

For healthcare applications in soft wearable sensors or decorative lighting,

32 | INNOVATIVE MATERIALS 4 2021

cholesteric liquid crystals are ideally suited. Until now though, an easy way of producing these materials and making devices from these materials has been lacking.

Researchers from the department of Chemical Engineering and Chemistry at TU/e in collaboration with TNO, DSM, Brightlands Materials Center (in the DynAM consortium), and SABIC have created a nature-inspired liquid crystal elastomer-based ink that can be 3D

printed on a surface via Direct-Ink-Writing (DIW). Lead author for the study is PhD candidate Jeroen Sol, with Albert Schenning and Michael Debije from the Stimuli-responsive Functional Materials and Devices (SFD) group heading the research project.

DIW is an extrusion-based 3D printing approach where an ink is dispensed from a small nozzle onto a surface on a layerby-layer basis. Current cholesteric liquid crystal inks can-not be printed with DIW, so the scientists created a liquid crystal

RESEARCH ink compatible with DIW. The new liquid crystal ink has several key properties. First, the light reflective properties of the ink rely on the precise helical alignment of molecules through­ out the material which requires fine tuning of the printing process. Second, the molecules in the ink can self-assemble into such structures that display colours similar to natural iridescent materials, like those in butterfly wings. Third, the new ink has greater viscosity than previous inks, which makes it suitable for DIW printing.

Finally, the new ink is novel, easy to make, easy to process, and based on materials previously developed by the SFD research group at TU/e for light-reflective coatings, which help make it suitable for 3D printing.

The researchers also proved to be able to control molecular alignment at the nanoscale extremely accurately by varying the printing speed. This gave them more control over the appearance and light-reflecting properties of the material.

Given that the new liquid crystal ink can be printed with DIW, it could be used in future printing procedures for personalized medical devices such as thin wearable biosensors that interact visually and colourfully with the wearer.

The paper ‘Anisotropic iridescence and polarization patterns in a direct ink written chiral pho-tonic polymer’, Jeroen Sol, Lanti Yang, Nadia Grossiord, Albert Schenning, and Michael Debije, Advanced Materials, (2021) is online>

Text: TU Eindhoven>

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RESEARCH

Converting tamarind shells into an supercapacitors Tamarind is a tropical fruit, the pulp of which is used in the food industry. The shells are thrown away and end up in landfills in large quantities. However, a team of international scientists led

by Nanyang Technological University, Singapore (NTU Singapore) has found a way to deal with the waste problem. By processing the tamarind shells which are rich in carbon, the scientists converted the waste material into carbon nano­ sheets, which are a key component of supercapacitors - energy storage devices that are used in automobiles, buses, electric vehicles, trains, and elevators.

The team, made up of researchers from NTU Singapore, the Western Norway University of Applied Sciences in Norway, and Alagappa University in India, believes that these nanosheets, when scaled up, could be an eco-friendly alternative to their industrially prod uced counterparts, and cut down on waste at the same time.

To manufacture the carbon nanosheets, the researchers first washed tamarind fruit shells and dried them at 100°C for around six hours, before grinding them into powder. The scientists then baked the powder in a furnace for 150 minutes at 700-900 °C in the absence of oxygen to convert them into ultrathin sheets of carbon known as nanosheets.

electric conductivity, making them promising options for energy storage.

The tamarind shell-derived nanosheets also showed good thermal stability and

A representation of the experimental process, as well as photographs of the tamarind shell at every step (Source: NTU)

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A common material used to produce carbon nanosheets are industrial hemp fibres. However, they require to be heated at over 180 °C for 24 hours four times longer than that of tamarind shells, and at a higher temperature. This is before the hemp is further subjected to intense heat to convert them into carbon nanosheets.

The researchers hope to explore larger scale production of the carbon nanosheets with agricultural partners. They

are also working on reducing the energy needed for the production process, making it more environmentally friendly, and are seeking to improve the electrochemical properties of the nanosheets.

More at NTU> The paper titled ‘Cleaner production of tamarind fruit shell into bio-mass derived porous 3D-activated carbon nanosheets by CVD technique for supercapacitor applications’ published in Chemosphere, 2 June, 2021, 131033.

Its online>

RESEARCH

New material from a bath sponge The three-dimensional and porous material is inherently a filter. Coupled with the properties of atacamite, there is a wide range of potential for using the new material as an alternative to synthetic filters. According to the researchers, the experiment demonstrates for the first time that the composite material made from marine bath sponges can in principle be used in the development of sensors, catalysts, and antibacterial filter systems.

More at TU Freiberg> The team led by Prof. Hermann Ehrlich published the results in a current publication in the journal Advanced Materials titled ´Extreme Biomimetics: Designing of the First Nanostructured 3D Spongin-Atacamite Composite and its Application´.

Its online>

Prof. Hermann Ehrlich looks at a piece of the new material (Photo: TU Bergakademie Freiberg/C. Mokry)

Researchers at TU Bergakademie Freiberg developed an innovative material from a cultured marine sponge. When the fibers of the sponge react with a copper-containing ammonia solution, the mineral atacamite is formed. This mineral, which occurs only very rarely in nature, attaches itself so strongly to the sponge fibers that a robust material is created that has catalytic and antibacterial properties and could therefore potentially be used as a bio-based industrial filter.

The pieces of sponge were placed in an alkaline, copper-containing ammonia solution (pH 9) that simulates a copper bath from the manufacture of circuit boards for electronic components. About 12 hours later the sponge has turned blue - when dry it is stronger than before, but still very light.

Because of the alkaline circumstances the fibers of the spongin will open and the copper contained in the ammonia solution reacts immediately with the organic components of the spongin, especially with the amino acid residues, to form the mineral atacamite. Nanometer-sized crystals grow along with the spongin fiber and stabilize the framework and ensure that the sponge is retained in its unique micro-architecture.

In an acidic solution, the reaction runs backwards: the sponge is back returns to its original state and can be processed again for further applications. The newly developed material can therefore be recycled again and again.

Biological material meets alkaline, toxic Cu-based waste. a–d) A spongin-based porous microfibrous scaffold of Hippospongia communis bath sponge with the original 3D architecture, when placed in a model ammoniacal CuCl2 solution (a,b), is covered with a dense layer of green crystalline material (c,d), which has been identified in this study as atacamite. e) The crystalline phase remains firmly attached to the spongin fibers even after 72 hours of ultrasonic treatment at 37 °C (Illustration from the article)

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RESEARCH

Fabric that can stiffen on demand

Scientists from NTU Singapore and the California Institute of Technology (Caltech), United States, have developed a new type of ‘chain mail’ fabric that is flexible like cloth but can stiffen on demand. This work was published in Nature on August 11, titled ‘Structured fabrics with tunable mechanical properties.’

According to Chiara Daraio, Caltech’s G. Bradford Jones Professor of Mechanical Engineering and Applied Physics

and corresponding author of a study, the scientists wanted to create a fabric that goes from soft and foldable to rigid and load-bearing in a controllable way.

To explore what materials would work best, Daraio, together with former Caltech postdoctoral researcher Yifan Wang and former Caltech graduate student Liuchi Li, designed a number of configurations of linked particles, from linking rings to linking cubes to linking octahedrons (which resemble two pyramids connected at the base). The materials were 3D printed out of polymers and even metals, with help from Douglas Hofmann, principal scientist at JPL, which Caltech manages for NASA. These configurations were then simulated in a computer.

This eventually led to a lightweight textile-like material, 3D-printed from nylon plastic polymers which comprises hollow octahedrons (a shape with eight equal triangular faces) that interlock with each other. When encased in a plastic envelope and vacuum-packed, it becomes 25 times more rigid and can hold up over 50 times its own weight.

According to NTU Singapore This next-generation fabric paves the way for lightweight armour that can harden to protect a user against an impact, protective gear for athletes, and exoskeletons that can help the elderly to stand, walk and carry objects.

Moving forward, the team is looking to improve the material and fabric performance of their chain mail and to explore more methods of stiffening it, such as through magnetism, electricity or temperature.

A - diagram to show how the eight-sided triangles interlock with each other B - a 3D printed chain mail C - how the chain mail looks like when soft and non-compressed D - photo of two layers of chain mail put together when soft E - 3D models of how the chain mail is jammed together when compressed in a plastic envelop F - the two layers of chain mail enclosed and vacuum-packed in a plastic envelope, bearing a load that is 50 times its weight

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Caltech> NTU>

Video

ENTERPRISE EUROPE NETWORK

Enterprise Europe Network (EEN) supports companies with international ambitions The Enterprise Europe Network (EEN) is an initiative of the European Commission that supports entrepreneurs in seeking partners to innovate and do business abroad. The Network is active in more than 60 countries worldwide.

It brings together 3,000 experts from more than 600 member organisations – all renowned for their excellence in business support.

Database

Every company can participate by adjusting its profile to the database. This company will be brought to the attention in the country in which it wants to become active. At the same time it is possible to search for partners.

EEN advisers actively assist in compiling the profile, which is drawn up in a certain format. The EEN websites also contain foreign companies that are looking for Dutch companies and organizations for commercial or technological cooperation. The EEN advisers support the search for a cooperation partner by actively deploying contacts within the network. In addition, Company Missions

and Match Making Events are regularly organized. All these services are free of charge.

There are five types of profiles:

• Business Offer:

the company offers a product

Video: How Enterprise Europe Network works

• Business Request:

the company is looking for a product

• Technology Offer:

the company offers a technology

• Technology Request:

the company is looking for a technology

• Research & Development Request:

the organization seeks cooperation for research

When a company has both a Business Offer and a Business Request (or another combination), two (or even more if applicable) profiles are created.

The profile includes the most essential

information about the nature of the supply or demand, the ‘type of partner’ that is intended and the expected cooperation structure.

Get in touch with your local network contact point by selecting the country and city closest to where your business is based. They can help you with advice, support and opportunities for international partnerships.

For sustainable building and the creative industry, contact ir. drs. Hans Kamphuis: T: +31 (0) 88 042 1124 M: 06 25 70 82 76 E: hans.kamphuis@rvo.nl For Materials contact Nils Haarmans: T: +31 (0) 88 062 5843 M: 06 21 83 94 57 More information websites can be found at the Europe Network websites: www.enterpriseeuropenetwork.nl http://een.ec.europa.eu

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ENTERPRISE EUROPE NETWORK The Enterprise Europe Network Materials Database: Request for partnership: August 2021.

Intrested? contact hans.kamphuis@rvo.nl>

A French company in the childcare industry is looking for eco-friendly materials (recycled and bio-based materials) in plastics and packaging industries.

The company researches solutions for future development to include in their range of products for babies. The company wants to establish technical cooperation agreement or manufacturing agreement.

Swiss SME is looking for a board manufacturer that produces or a research & development partner that develops an open-pore, air-permeable, flame retardant, lightweight board.

The board size is approximately 3.0 m x 1.2 m.

The product can be redeveloped or delivered as already existing board material. It will be used in the building industry.

The SME seeks a partner for a manufacturing or a technical cooperation agreement possibly including development.

A Spanish technology research centre specialised in plastics, composites, polymer blends, and polymer materials for packaging is looking for novel commercial biobased and biodegradable polymers.

The technology centre is looking for bio-based alternatives to adapt to current expanded polystyrene packaging under commercial agreement with technical assistance. If they do not find the commercial solution they consider a future development under research or technical cooperation agreement.

A Greek medical technology start-up has invented an innovative splint for arm fractures.

The splint is made of PLA (polylactic acid). TIn order to expand their production, the startup is looking for companies with ISO 13485 certification who provide PLA laser cutting services. The type of partnership considered will be a manufacturing agreement.

WE KUNNEN NIET ZONDER NATUUR Word nu lid op natuurmonumenten.nl en ontvang 4 x per jaar het magazine Puur Natuur

38 | INNOVATIVE MATERIALS 4 2021

EVENTS The corona crisis makes it uncertain whether events will actually take place on the scheduled date. Many events are postponed or online. The Agenda below shows the state of affairs as of September 2021.

For recent updates: www.innovatievematerialen.nl Plastics Recycling World Exhibition 2021 29 - 30 September 2021, Essen

Solids 2022 16 - 17 February 2022, Dortmund

Vitrum 2021 5 - 8 October 2021, Milan

Ulmer Betontage 2022 22 - 24 February 2022, Ulm

Lijmen 2021 12 Oktober 2021, Veldhoven

JEC World 2022 8 - 10 March 2022, Paris-Nord

Deburring EXPO 12 - 14 October 2021, Karlsruhe

BLE.CH 2022 8 - 10 March 2022, Bern

Fakuma 12 - 16 October 2021, Friedrichshafen

ESEF 2022 15 - 18 March 2022, Utrecht

Euro PM2021 Congress and Exhibition 18 - 22 October 2021, Lissabon

Material District 2020 5 - 7 April 2022, Utrecht

Architect@Work 2021 Belgium 21 - 22 October 2021, Kortrijk

FIP Solution Plastique 5 - 8 April 2022, Lyon

iENA Nürnberg 4 - 7 November 2021, Neurenberg

Nordbygg 2022 26 - 29 April 2022, Stockholm

BOUWXPO 12 - 14 November 2021, Kortrijk

Glasdag 2022 9 of 16 June 2022, Leusden

3D Delta week 6 - 10 December 2021

SurfaceTechnology GERMANY, 21 - 23 June 2022, Stuttgart

Digital BAU 15 - 17 FebruarY 2022, Cologne

Ceramitec 2022 21 - 24 June 2022

39 | INNOVATIVE MATERIALS 4 2021

Innovative Materials, the international version of the Dutch magazine Innovatieve Materialen, is now available in English. Innovative Materials is an interactive, digital magazine about new and/or innovatively applied materials.

Innovative Materials provides information on material innovations, or innovative use of materials. The idea is that the ever increasing demands lead to a constant search for better and safer products as well as material and energy savings. Enabling these innovations is crucial, not only to be competitive but also to meet the challenges of enhancing and protecting the environment, like durability, C2C and carbon footprint.

By opting for smart, sustainable and innovative materials constructors, engineers and designers obtain more opportunities to distinguish themselves.

As a platform Innovative Materials wants to help to achieve this by connecting supply and demand.

Innovative Materials is distributed among its own subscribers/network, but also through the networks of the partners. In 2021 this includes organisations like M2i, MaterialDesign, 4TU (a cooperation between the four Technical Universities in the Netherlands), the Bond voor Materialenkennis (material sciences), SIM Flanders, FLAM3D, RVO and Material District.