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Photo: Pixabay
16.02.2021

Carbon with Multiple Lives: Bringing Innovations in Carbon Fiber Recycling to Market

When it comes to the future of motorized mobility, everyone talks about the power drive: How much e-car, how much combustion engine can the environment tolerate and how much do people need? At the same time, new powertrains place ineased demands not only on the engine, but also on its housing and the car body: Carbon fibers are often used for such demanding applications. Like the powertrain of the future, the materials on the vehicle should also be environmentally friendly. That is why recycling of carbon fibers is required. Institutes of the Zuse Community have developed solutions for this.

Carbon fibers consist almost completely of pure carbon. It is extracted from the plastic polyacrylonitrile at 1,300 degrees Celsius, using a lot of energy. The advantages of carbon fibers: They have almost no dead weight, are enormously break-resistant and sturdy. These properties are needed, for example, in the battery box of electric vehicles in structural components of a car body.

When it comes to the future of motorized mobility, everyone talks about the power drive: How much e-car, how much combustion engine can the environment tolerate and how much do people need? At the same time, new powertrains place ineased demands not only on the engine, but also on its housing and the car body: Carbon fibers are often used for such demanding applications. Like the powertrain of the future, the materials on the vehicle should also be environmentally friendly. That is why recycling of carbon fibers is required. Institutes of the Zuse Community have developed solutions for this.

Carbon fibers consist almost completely of pure carbon. It is extracted from the plastic polyacrylonitrile at 1,300 degrees Celsius, using a lot of energy. The advantages of carbon fibers: They have almost no dead weight, are enormously break-resistant and sturdy. These properties are needed, for example, in the battery box of electric vehicles in structural components of a car body.

The Saxon Textile Research Institute (STFI), for instance, is currently working with industrial partners on combining the static-mechanical strengths of carbon fibers with vibration damping properties to improve the housings of electric motors in cars. The project, which is funded by the German Federal Ministry for Economic Affairs and Energy, is aimed at developing hybrid nonwovens that contain other fibers, in addition to carbon fiber, as a reinforcement. "We want to combine the advantages of different fiber materials and thereby develop a product that is optimally tailored to the requirements", explains Marcel Hofmann, head of department of Textile Lightweight Construction at STFI.

The Chemnitz researchers would therefore complement previous nonwoven solutions. They look back on 15 years of working with recycled carbon fibers. The global annual demand for the high-value fibers has almost quadrupled in the past decade, according to the AVK Industry Association to around 142,000 t most recently. "Increasing demand has brought recycling more and more into focus", says Hofmann. According to him, carbon fiber waste is available for about one-tenth to one-fifth of the price of primary fibers, but they still need to be processed. The key issue for the research success of recycled fibers is competitive applications. STFI has found these not only in cars, but also in the sports and leisure sector as well as in medical technology, for example in components for computer tomography. "While metals or glass fibers cast shadows as potential competing products, carbon does not interfere with the image display and can fully exploit its advantages", explains Hofmann.
 
Using Paper Know-How
If recycled carbon fibers can pass through the product cycle again, this significantly improves their carbon footprint. At the same time it applies: The shorter the carbon fibers, the less attractive they are for further recycling. With this in mind, the Cetex Research Institute and the Papiertechnische Stiftung (PTS), both members of the Zuse Community, developed a new process as part of a research project that gives recycled carbon fibers, which previously seemed unsuitable, a second product life. "While classic textile processes use dry processing for the already very brittle recycled carbon fibers in fiber lengths of at least 80 mm, we dealt with a process from the paper industry that processes the materials wet. At the end of the process, in very simplified terms, we obtained a laminar mat made of recycled carbon fibers and chemical fibers", says Cetex project engineer Johannes Tietze, explaining the process by which even 40 mm short carbon fibers can be recycled into appealing intermediates.

The resulting product created in a hot pressing process serves as the base material for heavy-duty structural components. In addition, the mechanical properties of the semi-finished products were improved by combining them with continuous fiber-reinforced tapes. The researchers expect the recycled product to compete with glass-fiber-reinforced plastics, for example in applications in rail and vehicle construction. The results are now being incorporated into further research and development in
the cooperation network of Ressourcetex, a funded association with 18 partners from industry and science.

Successful Implementation in the Automotive Industry
Industrial solutions for the recycling of carbon fiber production waste are being developed at the Thuringian Institute of Textile and Plastics Research (TITK). Several of these developments were industrially implemented with partners at the company SGL Composites in Wackersdorf, Germany. The processing of the so-called dry waste, mainly from production, is carried out in a separate procedure. "Here, we add the opened fibers to various processes for nonwoven production", says the responsible head of the department at TITK, Dr. Renate Lützkendorf . In addition to developments for applications e.g. in the BMW i3 in the roof or rear seat shell, special nonwovens and processes for the production of Sheet Molding Compounds (SMC) were established at TITK. These are thermoset materials consisting of reaction resins and reinforcing fibers, which are used to press fiber-plastic composites. This was used, for example, in a component for the C-pillar of the BMW 7 Series. "In its projects, TITK is primarily focusing on the development of more efficient processes and combined procedures to give carbon fiber recycling materials better opportunities in lightweight construction applications, also in terms of costs", says Lützkendorf. The focus is currently on the use of CF recycled fibers in thermoplastic processes for sheet and profile extrusion. "The goal is to combine short- and continuous-fiber reinforcement in a single, high-performance process step."

1) Since February 1st, 2021, Dr.-Ing. Thomas Reussmann succeeds Dr.-Ing. Renate Lützkendorf, who retired 31 January.

Source:

Zuse Community

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15.12.2020

Protection against Corona: Materials research provides findings at institutes of the Zuse Community

As the year draws to a close, expectations are growing that protection against COVID-19 will soon be available. Until this is the case for large sections of the population, the successes achieved in research and industry to protect against the virus in 2020 offer a good starting point in the fight against corona and beyond. At institutes in the Zuse community, progress have been made not only in medical but also in materials research.

As the year draws to a close, expectations are growing that protection against COVID-19 will soon be available. Until this is the case for large sections of the population, the successes achieved in research and industry to protect against the virus in 2020 offer a good starting point in the fight against corona and beyond. At institutes in the Zuse community, progress have been made not only in medical but also in materials research.

These successes in materials research include innovations in the coating of surfaces. "In the wake of the pandemic, the demand for antiviral and antimicrobial surfaces has risen sharply, and we have successfully intensified our research in this area," explains Dr. Sebastian Spange, Head of Surface Technology at the Jena research institute INNOVENT. He expects to see an increasing number of products with antiviral surfaces in the future. "Our tests with model organisms show that an appropriate coating of surfaces works", emphasizes Spange. The spectrum of techniques used by INNOVENT includes flame treatment, plasma coating and the so-called Sol-Gel process, in which organic and inorganic substances can be combined in one layer at relatively low temperatures. According to Spange, materials for the coatings can be antibacterial metal compounds as well as natural substances with antiviral potential.

Nonwovens produced for mask manufacturers
In 2020, the textile expertise of numerous institutes in the Zuse community ensured that application-oriented research could prove its worth in the practical fight against pandemics. After the shortage of mask supplies in Germany at the beginning of the pandemic, textile research institutes reacted to the shortage by jumping into the breach. The Saxon Textile Research Institute (STFI), for example, converted its research facilities to the production of nonwovens to supply German and European manufacturers of particle filtering protective masks. "From March to November 2020, we supplied nonwovens to various manufacturers in order to provide the best possible support for mask production and thus help contain the pandemic. At a critical time for industry and the population, we were able to help relieve critical production capacity - an unaccustomed role for a research institute, but one we would assume again in similar situations," explains Andreas Berthel, Managing Commercial Director of STFI.

Development of reusable medical face masks
For the improvement of everyday as well as medical face masks the German Institutes for Textile and Fiber Research (DITF) are working on this project. In cooperation with an industrial partner, they are currently developing in Denkendorf, among other things, reusable medical face masks made of high-performance precision fabric using Jacquard weaving technology. The multiple use avoids waste and possible supply bottlenecks.

There are regulations for all types of masks, now also for everyday masks. At Hohenstein, compliance with standards for masks is checked. A new European guideline defines minimum requirements for the design, performance evaluation, labelling and packaging of everyday masks. "As a testing laboratory for medical products, we test the functionality of medical masks from microbiological-hygienic and physical aspects", explains Hohenstein's Managing Director Prof. Dr. Stefan Mecheels. In this way, Hohenstein supports manufacturers, among other things, with technical documentation to prove the effectiveness and safety. Respiratory protection masks (FFP 1, FFP 2 and FFP 3) have been tested at the Plastics Centre (SKZ) in Würzburg since the middle of this year. Among other things, inhalation and exhalation resistance and the passage of particles are tested. In addition, SKZ itself has entered into mask research. In cooperation with a medical technology specialist, SKZ is developing an innovative mask consisting of a cleanable and sterilizable mask carrier and replaceable filter elements.

ILK tests for mouth-nose protection
The fight against Corona is won by the contributions of humans: Of researchers in laboratories, of developers and manufacturers in the Industry as well as from the citizens on the street.
Against this background, the Institute for Air and Refrigeration Technology (ILK) in Dresden has carried out investigations into the permeability of the mouth and nose protection (MNS), namely on possible impairments when breathing through the mask as well as the protective function of everyday masks. Result: Although the materials used for the mouth-nose protection are able to retain about 95 percent of the exhaled droplets, "under practical aspects and consideration of leakages" it can be assumed that about 50 percent to 70 percent of the droplets enter the room, according to the ILK. If the mask is worn below the nose only, it can even be assumed that about 90 percent of the exhaled particles will enter the room due to the large proportion of nasal breathing. This illustrates the importance of tight-fitting and correctly worn mouth and nose protection. "On the other hand, from a physical point of view there are no reasons against wearing a mask", ILK managing director Prof. Dr. Uwe Franzke emphasizes. The researchers examined the CO2 content in the air we breathe as well as the higher effort required for breathing and based this on the criterion of overcoming the pressure loss. "The investigations on pressure loss showed a small, but practically irrelevant increase," explains Franzke.

The complete ILK report "Investigations on the effect of mouth and nose protection (MNS)" is available here.

Photocredits: Hohenstein
01.09.2020

Research Projects of the Zuse Community: Think about Recycling when Designing …

How applied research in cooperation with industry can lead to high-quality recycling solutions is explained by the Zuse community with its "Design for Recycling" series.

How applied research in cooperation with industry can lead to high-quality recycling solutions is explained by the Zuse community with its "Design for Recycling" series.

Artificial Turf of the Future
Textiles are much more than just clothes. The industry is a key customer for both synthetic and natural fibers. However, their textile products are often close to the consumer - this applies, for example, to the leisure industry or sports field construction, as is the case with artificial turf.
     
On sports fields, textiles are, so to speak, trampled underfoot, namely when playing on artificial turf. In Germany alone there are around 5,000 artificial turf pitches registered for football. But under the green stubble hides a heavy burden - for clubs and the environment. According to information from the IAKS Germany trade association, around 5 kg of granulate per square meter of artificial turf is infilled in Germany, and this figure is likely to be considerably higher in other countries. "In the case of artificial turf with a fiber length of 42 mm, only 12 mm look out of the mass of infill materials that have been applied to the surface," Dr. Ulrich Berghaus of Morton Extrusionstechnik GmbH, a leading manufacturer of artificial turf, explains. Nowadays, a new pitch is calculated to contain almost 50 percent of the old pitch - as infill material. But as a microplastic this can cause problems - alternatives have to be found. Together with the Aachen Institute for Floor Systems (TFI), Morton Extrusionstechnik is working on the artificial turf of the future, which can do without problematic infill materials.

The researchers at the TFI are now called upon to ensure that the nubs of the artificial turf will hold well in the carrier material in future, even without polyurethane and latex. "Ideally, artificial turf would be made of just one polymer," TFI project manager Dirk Hanuschik says. Because, similar to food packaging, inseparable material composites are poison for high-quality recycling. Hanuschik and his team are therefore researching with their industrial partner into an artificial turf design that does not require any polyurethane or latex for the backing of the carrier material. In a thermobonding facility, the artificial turf nubs are to be melted directly onto the base material, not glued on. Nevertheless, a durability of around 12-15 years is the goal - as with artificial turf laid today. He can test the new materials on the industrial coating plant, which is on a smaller scale at the TFI. The first production plant is scheduled to go into operation as early as the middle of next year.
     
"The practical project of the TFI is an excellent example of how industrial research from the Zuse community creates concrete benefits for people through sustainable recycling management. Research on 'Design for Recycling' is the focus of many of our institutes. Their close cooperation with companies and their interdisciplinary approach offer the best conditions for further innovations," explains the President of the Zuse Community, Prof. Martin Bastian.


Recycling in the Fashion Industry
Recycling is more than just a trend. In the future, fashion should increasingly include useful recycling: People in Germany buy an average of 26 kg of textiles per capita per year, including 12-15 kg of clothing. Given these large quantities, high-quality recycling is a major challenge. Improved recycling includes a circular economy that thinks about the "life after", i.e. the next or renewed product, already when designing products. A current research project of the Zuse community shows how this can work for clothing.
     
Beverage bottles made of the plastic PET are already ideally suited for recycling, and not only for packaging, because of their purity of type. Under the motto "From the fiber to the fiber", this is what the applied research in the joint project DiTex is using for rental linen. The fibers used come from recycled PET bottles, and the rented linen itself is to be recycled back into linen after its first life cycle.

"Rented linen is also well suited to the 'Design for Recycling' concept because its use can be precisely tracked, which provides optimum conditions for recycling," project manager Dr. Anja Gerhardts from the Hohenstein Research Institute explains. The institute from Baden-Württemberg is responsible for textile testing and product specifications in the project initiated and coordinated by the Institute for Ecological Economic Research (IÖW). For benefit rather than ownership, the partners in the alliance are developing a recyclable line of bed linen, as well as polo and business shirts. The shirts will serve as uniforms for police and rescue services.

Intelligent label stores information
The laundry is equipped with a digital tracking ID throughout the entire usage cycle. This "intelligent" label stores information such as fiber origin, material composition and composition of the textile. This enables recycling companies to sort the products better, increase the recycling share and upgrade them. Numerous washing trials are now being carried out at Hohenstein to test how well the tracking tool is performing and what the tensile strength, degree of whiteness, color quality, durability and wearing comfort of the textiles are when they are washed, spun and dried up to 200 times in commercial textile services. "In DiTex we bring users, procurers and recyclers of textiles to one table to make recyclable product design a reality", Anja Gerhardts explains.

"Practical research on fibers and textiles is one of the core competences of many of our institute, be it for industrial technical products or consumer-oriented products. Projects like DiTex show innovative solutions for design for recycling. Thanks to the interdisciplinary approach in our association, other industries can also learn from such solutions," explains Dr. Annette Treffkorn, managing director of the Zuse community.

Source:

Zuse-Gemeinschaft