Textination Newsline

Researchers led by Keiji Numata at the RIKEN Center for Sustainable Resource Science in Japan, along with colleagues from the RIKEN Pioneering Research Cluster, have succeeded in creating a device that spins artificial spider silk that closely matches what spiders naturally produce. The artificial silk gland was able to re-create the complex molecular structure of silk by mimicking the various chemical and physical changes that naturally occur in a spider’s silk gland. This eco-friendly innovation is a big step towards sustainability and could impact several industries. This study was published January 15 in the scientific journal Nature Communications.

Famous for its strength, flexibility, and light weight, spider silk has a tensile strength that is comparable to steel of the same diameter, and a strength to weight ratio that is unparalleled. Added to that, it’s biocompatible, meaning that it can be used in medical applications, as well as biodegradable. So why isn’t everything made from spider silk? Large-scale harvesting of silk from spiders has proven impractical for several reasons, leaving it up to scientists to develop a way to produce it in the laboratory.

Spider silk is a biopolymer fiber made from large proteins with highly repetitive sequences, called spidroins. Within the silk fibers are molecular substructures called beta sheets, which must be aligned properly for the silk fibers to have their unique mechanical properties. Re-creating this complex molecular architecture has confounded scientists for years. Rather than trying to devise the process from scratch, RIKEN scientists took a biomimicry approach. As Numata explains, “in this study, we attempted to mimic natural spider silk production using microfluidics, which involves the flow and manipulation of small amounts of fluids through narrow channels. Indeed, one could say that that the spider’s silk gland functions as a sort of natural microfluidic device.”

The device developed by the researchers looks like a small rectangular box with tiny channels grooved into it. Precursor spidroin solution is placed at one end and then pulled towards the other end by means of negative pressure. As the spidroins flow through the microfluidic channels, they are exposed to precise changes in the chemical and physical environment, which are made possible by the design of the microfluidic system. Under the correct conditions, the proteins self-assembled into silk fibers with their characteristic complex structure.

The researchers experimented to find these correct conditions, and eventually were able to optimize the interactions among the different regions of the microfluidic system. Among other things, they discovered that using force to push the proteins through did not work; only when they used negative pressure to pull the spidroin solution could continuous silk fibers with the correct telltale alignment of beta sheets be assembled.

“It was surprising how robust the microfluidic system was, once the different conditions were established and optimized,” says Senior Scientist Ali Malay, one of the paper’s co-authors. “Fiber assembly was spontaneous, extremely rapid, and highly reproducible. Importantly, the fibers exhibited the distinct hierarchical structure that is found in natural silk fiber.”

The ability to artificially produce silk fibers using this method could provide numerous benefits. Not only could it help reduce the negative impact that current textile manufacturing has on the environment, but the biodegradable and biocompatible nature of spider silk makes it ideal for biomedical applications, such as sutures and artificial ligaments.

“Ideally, we want to have a real-world impact,” says Numata. “For this to occur, we will need to scale-up our fiber-production methodology and make it a continuous process. We will also evaluate the quality of our artificial spider silk using several metrics and make further improvements from there.”

The low-cost FibeRobo, which is compatible with existing textile manufacturing techniques, could be used in adaptive performance wear or compression garments.

Researchers from MIT and Northeastern University developed a liquid crystal elastomer fiber that can change its shape in response to thermal stimuli. The fiber, which is fully compatible with existing textile manufacturing machinery, could be used to make morphing textiles, like a jacket that becomes more insulating to keep the wearer warm when temperatures drop.

Instead of needing a coat for each season, imagine having a jacket that would dynamically change shape so it becomes more insulating to keep you warm as the temperature drops.
A programmable, actuating fiber developed by an interdisciplinary team of MIT researchers could someday make this vision a reality. Known as FibeRobo, the fiber contracts in response to an increase in temperature, then self-reverses when the temperature decreases, without any embedded sensors or other hard components.

The low-cost fiber is fully compatible with textile manufacturing techniques, including weaving looms, embroidery, and industrial knitting machines, and can be produced continuously by the kilometer. This could enable designers to easily incorporate actuation and sensing capabilities into a wide range of fabrics for myriad applications.

The fibers can also be combined with conductive thread, which acts as a heating element when electric current runs through it. In this way, the fibers actuate using electricity, which offers a user digital control over a textile’s form. For instance, a fabric could change shape based on any piece of digital information, such as readings from a heart rate sensor.

“We use textiles for everything. We make planes with fiber-reinforced composites, we cover the International Space Station with a radiation-shielding fabric, we use them for personal expression and performance wear. So much of our environment is adaptive and responsive, but the one thing that needs to be the most adaptive and responsive — textiles — is completely inert,” says Jack Forman, a graduate student in the Tangible Media Group of the MIT Media Lab, with a secondary affiliation at the Center for Bits and Atoms, and lead author of a paper on the actuating fiber.

He is joined on the paper by 11 other researchers at MIT and Northeastern University, including his advisors, Professor Neil Gershenfeld, who leads the Center for Bits and Atoms, and Hiroshi Ishii, the Jerome B. Wiesner Professor of Media Arts and Sciences and director of the Tangible Media Group. The research will be presented at the ACM Symposium on User Interface Software and Technology.

Morphing materials
The MIT researchers wanted a fiber that could actuate silently and change its shape dramatically, while being compatible with common textile manufacturing procedures. To achieve this, they used a material known as liquid crystal elastomer (LCE).

A liquid crystal is a series of molecules that can flow like liquid, but when they’re allowed to settle, they stack into a periodic crystal arrangement. The researchers incorporate these crystal structures into an elastomer network, which is stretchy like a rubber band.

As the LCE material heats up, the crystal molecules fall out of alignment and pull the elastomer network together, causing the fiber to contract. When the heat is removed, the molecules return to their original alignment, and the material to its original length, Forman explains.

By carefully mixing chemicals to synthesize the LCE, the researchers can control the final properties of the fiber, such as its thickness or the temperature at which it actuates.

They perfected a preparation technique that creates LCE fiber which can actuate at skin-safe temperatures, making it suitable for wearable fabrics.

“There are a lot of knobs we can turn. It was a lot of work to come up with this process from scratch, but ultimately it gives us a lot of freedom for the resulting fiber,” he adds.
However, the researchers discovered that making fiber from LCE resin is a finicky process. Existing techniques often result in a fused mass that is impossible to unspool.

Researchers are also exploring other ways to make functional fibers, such as by incorporating hundreds of microscale digital chips into a polymer, utilizing an activated fluidic system, or including piezoelectric material that can convert sound vibrations into electrical signals.

Fiber fabrication
Forman built a machine using 3D-printed and laser-cut parts and basic electronics to overcome the fabrication challenges. He initially built the machine as part of the graduate-level course MAS.865 (Rapid-Prototyping of Rapid-Prototyping Machines: How to Make Something that Makes [almost] Anything).

To begin, the thick and viscous LCE resin is heated, and then slowly squeezed through a nozzle like that of a glue gun. As the resin comes out, it is cured carefully using UV lights that shine on both sides of the slowly extruding fiber.

If the light is too dim, the material will separate and drip out of the machine, but if it is too bright, clumps can form, which yields bumpy fibers.

Then the fiber is dipped in oil to give it a slippery coating and cured again, this time with UV lights turned up to full blast, creating a strong and smooth fiber. Finally, it is collected into a top spool and dipped in powder so it will slide easily into machines for textile manufacturing.
From chemical synthesis to finished spool, the process takes about a day and produces approximately a kilometer of ready-to-use fiber.

“At the end of the day, you don’t want a diva fiber. You want a fiber that, when you are working with it, falls into the ensemble of materials — one that you can work with just like any other fiber material, but then it has a lot of exciting new capabilities,” Forman says.

Creating such a fiber took a great deal of trial and error, as well as the collaboration of researchers with expertise in many disciplines, from chemistry to mechanical engineering to electronics to design.

The resulting fiber, called FibeRobo, can contract up to 40 percent without bending, actuate at skin-safe temperatures (the skin-safe version of the fiber contracts up to about 25 percent), and be produced with a low-cost setup for 20 cents per meter, which is about 60 times cheaper than commercially available shape-changing fibers.

The fiber can be incorporated into industrial sewing and knitting machines, as well as nonindustrial processes like hand looms or manual crocheting, without the need for any process modifications.
The MIT researchers used FibeRobo to demonstrate several applications, including an adaptive sports bra made by embroidery that tightens when the user begins exercising.

They also used an industrial knitting machine to create a compression jacket for Forman’s dog, whose name is Professor. The jacket would actuate and “hug” the dog based on a Bluetooth signal from Forman’s smartphone. Compression jackets are commonly used to alleviate the separation anxiety a dog can feel while its owner is away.

In the future, the researchers want to adjust the fiber’s chemical components so it can be recyclable or biodegradable. They also want to streamline the polymer synthesis process so users without wet lab expertise could make it on their own.

Forman is excited to see the FibeRobo applications other research groups identify as they build on these early results. In the long run, he hopes FibeRobo can become something a maker could buy in a craft store, just like a ball of yarn, and use to easily produce morphing fabrics.

“LCE fibers come to life when integrated into functional textiles. It is particularly fascinating to observe how the authors have explored creative textile designs using a variety of weaving and knitting patterns,” says Lining Yao, the Cooper-Siegel Associate Professor of Human Computer Interaction at Carnegie Mellon University, who was not involved with this work.

This research was supported, in part, by the William Asbjornsen Albert Memorial Fellowship, the Dr. Martin Luther King Jr. Visiting Professor Program, Toppan Printing Co., Honda Research, Chinese Scholarship Council, and Shima Seiki. The team included Ozgun Kilic Afsar, Sarah Nicita, Rosalie (Hsin-Ju) Lin, Liu Yang, Akshay Kothakonda, Zachary Gordon, and Cedric Honnet at MIT; and Megan Hofmann and Kristen Dorsey at Northeastern University.

As humanity grapples with climate change and rising sea levels, our collective imagination is more critical than ever. In light of this, bcomp presents the phenomenal work initiated by the students from Institut auf dem Rosenberg in St. Gallen and SAGA Space Architects. They’ve developed an extraordinary solution to address the environmental challenges we face: the ‘Blue Nomad’ floating habitat.

‘Blue Nomad’ is a solar-powered home designed for comfortable living on the ocean. It symbolises a future where we must explore and adapt to the changing earth’s environment. Drawing inspiration from the first Polynesian nomadic settlements and equipped with solar panels for self-sustainability, the habitat promotes a vision of living and traveling on water.

bcomp is particularly excited about the project as the scaled model that was exhibited in London and Monaco prominently features their very own ampliTex™ flax fibres. A plan of building an actual prototype of the floating home is being developed by Institut auf dem Rosenberg and SAGA. It could be made from a structurally optimised weave of flax fibre, showcasing the future of organic and regenerative high-performance materials replacing conventional synthetic and fossil-based technologies. As a company, bcomp is proud to provide sustainable material solutions, and seeing their flax fibres used in such an innovative and meaningful project is both humbling and inspiring.

‘Blue Nomad’ isn’t just a solitary habitat, but a concept for a new kind of community. Imagined as modular blocks, these habitats can form larger communities and oceanic farms, allowing inhabitants to share resources while moving from one oceanic farm to the next. It’s a striking vision of a future where the lines between land and water blur, and sustainability and community building lie at the heart of human settlements.

But this vision is not just theoretical. Plans are being made for a maiden voyage of ‘Blue Nomad’ across Europe, powered purely by solar energy, promoting ocean sustainability, climatology, and future nomadism.

This project serves as a powerful reminder of what can be achieved when education, innovative design, and sustainability are united. The ‘Blue Nomad’ represents the future we envision – a future where sustainable materials play a crucial role in safeguarding our planet.

The ‘Blue Nomad’ project was exhibited at the London Design Biennale 2023 as well as the Monaco Energy Boat Challenge where it was captivating visitors and garnering significant attention from the public.    

Ecole Polytechnique Fédérale de Lausanne (EPFL) researchers have developed fiber-like pumps that allow high-pressure fluidic circuits to be woven into textiles without an external pump. Soft supportive exoskeletons, thermoregulatory clothing, and immersive haptics can therefore be powered from pumps sewn into the fabric of the devices themselves.

Many fluid-based wearable assistive technologies today require a large and noisy pump that is impractical – if not impossible – to integrate into clothing. This leads to a contradiction: wearable devices are routinely tethered to unearable pumps. Now, researchers at the Soft Transducers Laboratory (LMTS) in the School of Engineering have developed an elegantly simple solution to this dilemma.

“We present the world’s first pump in the form of a fiber; in essence, tubing that generates its own pressure and flow rate,” says LMTS head Herbert Shea. “Now, we can sew our fiber pumps directly into textiles and clothing, leaving conventional pumps behind.” The research has been published in the journal Science.

Lightweight, powerful…and washable
Shea’s lab has a history of forward-thinking fluidics. In 2019, they produced the world’s first stretchable pump.

“This work builds on our previous generation of soft pump,” says Michael Smith, an LMTS post-doctoral researcher and lead author of the study. “The fiber format allows us to make lighter, more powerful pumps that are inherently more compat-ible with wearable technology.”

The LMTS fiber pumps use a principle called charge injection electrohydrodynamics (EHD) to generate a fluid flow without any moving parts. Two helical electrodes embedded in the pump wall ionize and accelerate molecules of a special non-conductive liquid. The ion movement and electrode shape generate a net forward fluid flow, resulting in silent, vibration-free operation, and requiring just a palm-sized power supply and battery.

To achieve the pump’s unique structure, the researchers developed a novel fabrication technique that involves twisting copper wires and polyurethane threads together around a steel rod, and then fusing them with heat. After the rod is removed, the 2 mm fibers can be integrated into textiles using standard weaving and sewing techniques.

The pump’s simple design has a number of advantages. The materials required are cheap and readily available, and the manufacturing process can be easily scaled up. Because the amount of pressure generated by the pump is directly linked to its length, the tubes can be cut to match the application, optimizing performance while minimizing weight. The robust design can also be washed with conventional detergents.

From exoskeletons to virtual reality
The authors have already demonstrated how these fiber pumps can be used in new and exciting wearable technologies. For example, they can circulate hot and cold fluid through garments for those working in extreme temperature environments or in a therapeutic setting to help manage inflammation; and even for those looking to optimize athletic performance.

“These applications require long lengths of tubing anyway, and in our case, the tubing is the pump. This means we can make very simple and lightweight fluidic circuits that are convenient and comfortable to wear,” Smith says.

The study also describes artificial muscles made from fabric and embedded fiber pumps, which could be used to power soft exoskeletons to help patients move and walk.

The pump could even bring a new dimension to the world of virtual reality by simulating the sensation of temperature. In this case, users wear a glove with pumps filled with hot or cold liquid, allowing them to feel temperature changes in response to contact with a virtual object.

Pumped up for the future
The researchers are already looking to improve the performance of their device. “The pumps already perform well, and we’re confident that with more work, we can continue to make improvements in areas like efficiency and lifetime,” says Smith. Work has already started on scaling up the production of the fiber pumps, and the LMTS also has plans to embed them into more complex wearable devices.

“We believe that this innovation is a game-changer for wearable technology,” Shea says.

Photonic fibers borrow from butterfly wings to enable invisible, indelible sorting labels

Less than 15% of the 92 million tons of clothing and other textiles discarded annually are recycled—in part because they are so difficult to sort. Woven-in labels made with inexpensive photonic fibers, developed by a University of Michigan-led team, could change that.
 
“It’s like a barcode that’s woven directly into the fabric of a garment,” said Max Shtein, U-M professor of materials science and engineering and corresponding author of the study in Advanced Materials Technologies. “We can customize the photonic properties of the fibers to make them visible to the naked eye, readable only under near-infrared light or any combination.”

Ordinary tags often don’t make it to the end of a garment’s life—they may be cut away or washed until illegible, and tagless information can wear off. Recycling could be more effective if a tag was woven into the fabric, invisible until it needs to be read. This is what the new fiber could do.
 
Recyclers already use near-infrared sorting systems that identify different materials according to their naturally occurring optical signatures—the PET plastic in a water bottle, for example, looks different under near-infrared light than the HDPE plastic in a milk jug. Different fabrics also have different optical signatures, but Brian Iezzi, a postdoctoral researcher in Shtein’s lab and lead author of the study, explains that those signatures are of limited use to recyclers because of the prevalence of blended fabrics.

“For a truly circular recycling system to work, it’s important to know the precise composition of a fabric—a cotton recycler doesn’t want to pay for a garment that’s made of 70% polyester,” Iezzi said. “Natural optical signatures can’t provide that level of precision, but our photonic fibers can.”

The team developed the technology by combining Iezzi and Shtein’s photonic expertise—usually applied to products like displays, solar cells and optical filters—with the advanced textile capabilities at MIT’s Lincoln Lab. The lab worked to incorporate the photonic properties into a process that would be compatible with large-scale production.
 
They accomplished the task by starting with a preform—a plastic feedstock that comprises dozens of alternating layers. In this case, they used acrylic and polycarbonate. While each individual layer is clear, the combination of two materials bends and refracts light to create optical effects that can look like color. It’s the same basic phenomenon that gives butterfly wings their shimmer.

The preform is heated and then mechanically pulled—a bit like taffy—into a hair-thin strand of fiber. While the manufacturing process method differs from the extrusion technique used to make conventional synthetic fibers like polyester, it can produce the same miles-long strands of fiber. Those strands can then be processed with the same equipment already used by textile makers.

By adjusting the mix of materials and the speed at which the preform is pulled, the researchers tuned the fiber to create the desired optical properties and ensure recyclability. While the photonic fiber is more expensive than traditional textiles, the researchers estimate that it will only result in a small increase in the cost of finished goods.

“The photonic fibers only need to make up a small percentage—as little as 1% of a finished garment,” Iezzi said. “That might increase the cost of the finished product by around 25 cents—similar to the cost of those use-and-care tags we’re all familiar with.”

Shtein says that in addition to making recycling easier, the photonic labeling could be used to tell consumers where and how goods are made, and even to verify the authenticity of brand-name products. It could be a way to add important value for customers.

“As electronic devices like cell phones become more sophisticated, they could potentially have the ability to read this kind of photonic labeling,” Shtein said. “So I could imagine a future where woven-in labels are a useful feature for consumers as well as recyclers.”

The team has applied for patent protection and is evaluating ways to move forward with the commercialization of the technology.
The research was supported by the National Science Foundation and the Under Secretary of Defense for Research and Engineering.

• Successful approval of the 2nd funding period of the DFG Research Training Group 2430 "Interactive fibre-elastomer composites"

Researchers based in Dresden are going to develop a completely new class of materials in which actuators and sensors are integrated directly into flexible fibre composites – contrary to the state of the art. To this end, the German Research Foundation (DFG) approved the 2nd phase of Research Training Group 2430 "Interactive Fibre-Elastomer Composites" at TU Dresden in cooperation with the Leibniz Institute of Polymer Research Dresden. The spokesperson is Professor Chokri Cherif from the Institute for Textile Machinery and High-Performance Textile Materials Technology (ITM) at TU Dresden. A total of 22 doctoral students will be supported in eleven interdisciplinary sub-projects over the next 4.5 years, in addition to material and project funding.
 
As a result the simulation-based development of intelligent material combinations for so-called self-sufficient fibre composites shall be available. Actuators and sensors are already integrated into the structures and no longer placed subsequently, as it is actual the case. In the first funding phase, the important basis for the large two-dimensional deformations in soft, biomimetic structures were developed. The further funding by the DFG is a confirmation of the outstanding results achieved so far. Building on this, the second funding phase will focus on ionic and helical actuator-sensor concepts. Combined with intelligent design and control algorithms, self-sufficient, three-dimensionally deforming material systems will emerge. This will make these systems more robust, complex preforming patterns can be customised at the desired location - reversibly and contact-free.
 
Fibre composites are used increasingly in moving components due to their high specific stiffness and strengths as well as the possibility of tailoring these properties. By integrating adaptive functions into such materials, the need for subsequent actuator placement is eliminated and the robustness of the system is significantly improved. Actuators and sensors based on textiles, such as those being researched and developed at the ITM, are particularly promising in this respect, as they can be integrated directly into the fibre composites during the manufacturing process.

With their innovative properties, interactive fibre-elastomer composites are predestined for numerous fields of application in mechanical and vehicle engineering, robotics, architecture, orthotics and prosthetics: Examples include systems for precise gripping and transport processes (e.g. in hand prostheses, closures and deformable membranes) and components (e.g. trim tabs for land and water vehicles).

High-performance fibres that have been exposed to high temperatures usually lose their mechanical properties undetected and, in the worst case, can tear precisely when lives depend on them. For example, safety ropes used by fire brigades or suspension ropes for heavy loads on construction sites. Empa researchers have now developed a coating that changes color when exposed to high temperatures through friction or fire.

The firefighter runs into the burning building and systematically searches room by room for people in need of rescue. Attached to him is a safety rope at the other end of which his colleagues are waiting outside in front of the building. In an emergency - should he lose consciousness for any reason - they can pull him out of the building or follow him into the building for rescue. However, if this rope has been exposed to excessive heat during previous operations, it may tear apart. This means danger to life!

And up to now there has been no way of noticing this damage to the rope. 2021 a team of researchers from Empa and ETH Zurich has developed a coating which changes color due to the physical reaction with heat, thus clearly indicating whether a rope will continue to provide the safety it promises in the future.

Researchers from ETH Zurich and Empa developed a coating system in 2018 as part of a Master's thesis, which the Empa team was now able to apply to fibers. "It was a process involving several steps," says Dirk Hegemann from Empa's Advances Fibers lab. The first coatings only worked on smooth surfaces, so the method first had to be adapted so that it would also work on curved surfaces. Empa has extensive know-how in the coating of fibers - Hegemann and his team have already developed electrically conductive fibers in the past. The so-called sputtering process has now also been successfully applied to the latest coating.

Three layers are required to ensure that the fiber actually changes color when heated. The researchers apply silver to the fibre itself, in this case PET (i.e. polyester) and VectranTM, a high-tech fibre. This serves as a reflector - in other words, as a metallic base layer. This is followed by an intermediate layer of titanium nitrogen oxide, which ensures that the silver remains stable. And only then follows the amorphous layer that causes the color change: Germanium-antimony tellurium (GST), which is just 20 nanometers thick. When this layer is exposed to elevated temperatures, it crystallizes, changing the color from blue to white. The colour change is based on a physical phenomenon known as interference. Two different waves (e.g. light) meet and amplify or weaken each other. Depending on the chemical composition of the temperature-sensitive layer, this color change can be adjusted to a temperature range between 100 and 400 degrees and thus adapted to the mechanical properties of the fiber type.

Tailor-made solutions
The possible areas of application for the colour-changing fibres are still open, and Hegemann is currently looking for possible project partners. In addition to safety equipment for firefighters or mountaineers, the fibres can also be used for load ropes in production facilities, on construction sites, etc. In any case, research on the subject is far from complete. At present, it is not yet possible to store the fibers for long periods of time without losing their functionality. "Unfortunately, the phase-change materials oxidize over the course of a few months," says Hegemann. This means that the corresponding phase change - crystallization - no longer takes place, even with heat, and the rope thus loses its "warning signal". In any case, it has been proven that the principle works, and durability is a topic for future research, says Hegemann. "As soon as the first partners from industry register their interest in our own products, the fibers can be further optimized according to their needs".

Information:
Dr. Dirk Hegemann
Advanced Fibers
Tel. +41 58 765 7268
Dirk.Hegemann@empa.ch

For centuries, old textiles have been used to make tear fibers and processed into new textile products. This effective recycling is one of the oldest material cycles in the world. Today, it is not only clothing that is recycled, but also high-quality technical textiles. As the products of the textile industry evolve, so do the demands on textile recycling. The basis for this is a clear assessment and classification of raw materials.

In the research project of the German Institutes of Textile and Fiber Research Denkendorf (DITF) and the Sächsisches Textilforschungsinstitut e.V. (STFI - Saxony Textile Research Institute), a methodology is being developed that will make it possible to analyze the tearing as well as the subsequent processes with regard to fiber quality. The systematic analysis should make it possible to optimize the subsequent spinning processes in such a way that the recycled content of the yarn can be increased without the yarn properties differing significantly from those of a yarn consisting of 100% good fibers. These yarns can then be processed into sustainable textile products such as clothing or composite components.

The project, which is funded by the BMWi/IGF, is scheduled to run for two years and will end on December 31, 2022. The main benefits for the participating companies are to enable them to make greater use of secondary raw materials, to open up new markets through technologies or products developed in the project, to initiate synergies and long-term cooperation, and to prepare a joint market presence.    

The project includes several steps:

• Material selection and procurement
  Cotton fibers to be processed are obtained from used textiles (T-shirts) and waste from the cotton spinning mill. Aramid fibers are processed from used protective clothing and technical textiles.
• Optimization of the preparation / dissolution of the textiles
  To ensure that the fibers are detached from the corresponding textiles as gently as possible and with a not too high reduction, exact settings have to be found for the tearing process, which are technologically very demanding and require a lot of experience.
• Determination of the quality criteria for the evaluation of the fiber dissolution
  In order to define the quality criteria, the fibers coming from the tearing mill are determined by means of an MDTA-4 measuring device from Textechno GmbH & Co. KG. The criteria determined are to be used to characterize the (lowest possible) fiber shortening caused by the tearing process.
• Determination of optimized settings in the spinning process
  In order to determine the optimum settings for producing a yarn from the recycled fibers, they are spun after the rotor spinning process. By adjusting the spinning process, the aim is to produce a yarn that has good uniformity and also appropriate firmness.
• Production and comparison of yarns from recycled raw materials
  In order that the recycled fibers - consisting of aramid and cotton - can each be used to produce an area-measured material, the material is to be processed at industrial scale. For this purpose, the fibers are processed over a complete blowroom line with following sliver production over adapted cards. After drawing and the following roving production, yarns are produced according to the rotor or ring spinning process. The finished yarns are used to produce knitted fabrics.
• Coordination, analysis of results and preparation of reports
  The final report is prepared by the DITF and the STFI. The results will be transferred through publications, technical information to associations and trade fair presentations. Regular meetings with the participating companies are planned.

Textination spoke with Stephan Baz, Deputy Head of the Competence Center Staple Fiber, Weaving & Simulation, Head of Staple Fiber Technology and Markus Baumann, Research Associate at the Competence Center Staple Fiber, Weaving & Simulation (both DITF) as well as Bernd Gulich, Head of Department Nonwovens/Recycling and Johannes Leis, Research Associate Focus Nonwovens/Recycling (both STFI) about the current status of the funding project.

What is the current status of the project?
We are currently in the phase of carrying out trials and the iterative optimization of several project components. As expected, several loops are necessary for the mechanical preparation itself and also for the adjustment of the spinning process with the different variants. Ultimately, after all, the project aims at coordinating the processes of mechanical preparation and spinning as processing in order to achieve optimum results. At the same time, determining the quality criteria of the fibers produced is not trivial. This also requires the further development of processes and test methods that can be implemented productively in industry and that allow the quality of the fibers produced to be assessed effectively and unaffected by residual yarns, for example. What is really remarkable is the interest and willingness of the industry to drive the project work forward. The considerable quantities of materials required for our trials were purchased from ReSales Textilhandel und -recycling GmbH, Altex Textil-Recycling GmbH & Co. KG and Gebrüder Otto GmbH & Co. KG. Furthermore, with Temafa Maschinenfabrik GmbH, Nomaco GmbH & Co. KG, Schill + Seilacher GmbH, Spinnerei Neuhof GmbH & Co. KG and Maschinenfabrik Rieter AG, many members of the project-supporting committee are actively involved in the project, from consulting to the providing of technologies. The company Textechno Herbert Stein GmbH & Co. KG has provided a testing device of the type MDTA4 for the duration of the project and supports our work with regard to the evaluation of the mechanically prepared fibers. We are of course particularly pleased about this, as it has allowed us to look at and analyze several technologies in both mechanical preparation, testing and spinning. We expect to be able to make more detailed statements at the beginning of the coming year.

Which approaches do you think are particularly promising?
With regard to technologies, we must refer to the evaluation and analysis of the trials, which are currently still ongoing. We will be able to go into more detail in the first quarter of next year.

Of course, things are already emerging. With meta-aramid waste, promising approaches could be found very quickly; with post-consumer cotton, this is considerably more complex. Obviously, there is a link between the quality of the raw material and the quality of the products. In some cases, we have already been able to determine very low average fiber lengths in the procured goods; to a certain extent, these are of course directly reflected in the output of our processes. From this, and this is not a new finding, a great importance of the design of the textiles is again derived.

What are the challenges?
In addition to the expected high short fiber content, the residual yarns after the tearing process are an issue of particular focus. The proportion of these residual yarns can vary between the materials and preparation technologies, but the further dissolution of the products of the tearing process is essential.

If the processes are considered further in a utilization phase, the question of design naturally also arises for the best possible use of recycled fibers. Many problems, but also the approaches to solutions for the use of comparatively short fibers, can also be expected to apply to the (multiple) use of mechanically recycled fibers.

Can we speak of upcycling in the final product?
We see yarn-to-yarn recycling neither as upcycling nor downcycling, but as closed-loop recycling. The background is that the products are to go into the same application from which they came and have to compete with primary material. This means that certain specific requirements have to be met and at the same time there is considerable price pressure. In the case of downcycling, a significant reduction in properties is accepted, while in the case of upcycling, the higher-priced application can make up for the reprocessing effort. In the attempt to produce yarn material again from yarn material, both are only permissible to a small extent. This represents the particular challenge.

What does a recyclate prepared from used textiles mean for the spinning process?
Part of this question is to be answered in the project by the detailed classification of the processed fibers and is thus the subject of the tests currently underway. It turns out that, in addition to the rather obvious points such as significantly reduced fiber length, process disturbances due to undissolved fabrics and yarn pieces, there are also less obvious aspects to be considered, such as a significantly increased outgoing quantity for processing in the spinning process. The outgoing quantity is of particular interest here, because in the end the newly produced yarn should also contain a considerable proportion of prepared fibers.

What consequences does this have for textile machinery manufacturing?
The consequences that can already be estimated at the present time are that, particularly in the processing of cotton, the machinery in the spinning preparatory mill is specialized in the processing of (new) natural fibers with a certain amount of dirt. In contrast to new fibers, processed fibers are clean fibers with a significantly higher proportion of short fibers. Elements that are good at removing dirt also reject an increased amount of short fibers, which can lead to unintentionally high waste quantities under certain circumstances. It is therefore necessary to adapt the established machine technology to the new requirement profile of the raw material "processed fibers". Analogous adaptations are probably necessary along the entire processing chain up to the yarn. In the drafting system of the spinning machine, of course, this is due more to the high short fiber ratio than to elements that have been optimized for cleaning out dirt and foreign substances.

Nonwovens are an important component of different products of several uses, e.g. transport of humidity in sanitary products, insulation materials or filters. Nonwovens are usually produced on large engineering facilities. For this, experimental studies of design with regard to the optimization of these nonwoven-structures prove to be very difficult.

Influence Design Parameters
There are so many parameters of design, as for example fibers, surface weight or type of nonwoven bonding and finishing that are affecting the properties of nonwovens. For the change of one single parameter, e.g. the material of fiber, it is necessary to adapt the whole process of fabrication from the spinning of the fibers via their stacking to the nonwoven hardening.

Following the production of such a prototype a time consuming and cost-intensive characterization of the properties of nonwovens carried out experimentally has to be done.  Therefore, for this reason detailed studies considering several parameters of design are uneconomic.

Thus, micromechanical models of simulation are developed at Fraunhofer ITWM in cooperation with Procter & Gamble Service GmbH (P & G). By means of these models it is possible to forecast numerically the effective properties of nonwovens for diverse parameters of design. To virtually modify and optimize individual parameters in this connection it is only necessary to adapt the corresponding inputs of the model.

Fast Predictions Possible
In this case, the focus of the numerical predictions is primarily lying on the time-dependent behavior of the nonwovens.  The dynamic properties can be determined by means of numerical simulation of cyclic measurements. In doing so, a good correspondence of simulation and measurements is obtained.

Compared to experiments the required time of simulation for the behavior in case of low frequencies does not change. Therefore, we can obtain rapid forecasts for the long-term behavior (month till years) and the corresponding resilience of nonwovens using numerical models. A lot of alternatives can be simulated and studied within a few hours.

The fact that not only effective (macroscopic) properties of nonwovens can be computed, but also local physical values such as distribution of tension in binding agents and fibres is a further advantage of this micromechanical  approach. So, the simulation contributes to a better understanding of the properties of nonwovens.

Future designs deal with an extension of the models with regard to simulation of the productionv processes. By this, a fully digitalized layout design of nonwovens, from the manufacturing process till the optimization of functionality is possible.

• Finite resources and endless mountains of rubbish set the tone of the upcoming 25th edition of PERFORMANCE DAYS. Closing the loop means nothing is wasted, not even time, as recycled clothing gets recycled again and again.

In keeping with this topic, the trade fair organizers are planning expert discussion panels to help present the facts as well as visions of the future. Expect the corresponding displays of sustainable materials, chosen by the PERFORMANCE FORUM Jury. Look for materials such as fibers from recycled PET bottles, recyclable mono-component materials or blends, and shirts that decompose to biomass in a "Cradle-to-Cradle" approach. "Nothing to Waste - Closing the Loop" is open to the public at the Messe München fairgrounds and as a Digital Fair online starting on December 9-10, 2020.

The PERFORMANCE DAYS trade fair has chosen a new Focus Topic that concerns not only our own industry. The textile industry has long been achieving more efficient production by recycling its own waste products and using recycled materials from outside the industry, for example, PET-bottles. Nevertheless, textiles exist alongside glass, paper, metal, and plastics as a separate branch of waste management. Despite ambitious efforts at recycling by the waste and textile industries, the efficient use of textile waste as a resource remains a challenge. Compounding this challenge are the difficulties caused by a global world: production, consumers, and disposal sites are miles apart, shared expert knowledge about the other industries is lacking, and international standards and political support are nearly non-existent.

Final destination: the waste bin
Information from the Federal Office for the Environment shows that 0.8% of the oil produced is used in the textile industry for the production of new textiles. But the costly processing chain of this finite resource ends all too quickly in waste. A Greenpeace survey reveals outdated fashions or clothing of worn quality is thrown away within three years, only to land in the trash dumpsters. The European Environmental Agency estimates that 5.8 million tons of used textiles are discarded every year and either incinerated, used for landfill, or taken to mechanical-biological sewage treatment plants. Even if used clothing is collected by state or private companies, in many cases it cannot be sold (as second hand), donated, or recycled (into rags or insulating material). In the best case scenario, it is incinerated and converted to thermal energy.

Recycling and circular design
From an economic and environmental perspective, the term recycling refers to waste-free products, waste avoidance, and waste recovery and disposal. In our industry as it stands, recycling at the end of the product life cycle usually means converting the product into some other product, i.e., not clothing. This is the "Open-Loop" process. Accordingly, textiles are eventually incinerated, but the amount of energy recovered can vary greatly depending on how efficiently the waste incineration plant works. Such devaluing of the product to a product with less value than the original product is known as Downcycling. However, Downcycling is not the only solution: the "Closed-Loop" approach has the goal of making new clothes out of old ones through recycling. The closed loop for renewable natural resources, for example, can mean that natural fibers used in textiles will end up becoming soil, which is the nutrient for new natural fibers, i.e., a cradle-to-cradle approach. Synthetic garments similarly require extracting the man-made fibers and reprocessing them to produce another garment.

Planning for the end in advance
Rather than thinking about recycling opportunities at the end of the product life cycle, brands can already begin developing closed loop options while in the design phase. Among other things, designing out the waste can reduce the environmental impact of the products. To extend the useful life, consider leasing the materials and/or adding labels with instructions for disposal, repair, or repurposing. And, what about the idea of preparing 100% used textiles that can be reintroduced into the supply chain as 100% new textiles? Separating the different types of fiber used in blends is complex, cost-intensive, and further complicated when labels are non-existent (or no longer existing) or it is simply not (yet) technically possible. More and more clothing makers and suppliers are trying to avoid mixing fibers and are switching to "mono-materials" or "mono-components." Shirts are easy to make in this way, but if you add buttons, zippers, etc., the issue becomes more complex.

Nothing to waste - not even time
If you are like many end consumers, brand managers, and producers and want to make use of valuable resources in a more sustainable manner, register now on the trade fair website under "Visitor Login." There you can access a free trade fair ticket for December 9-10, 2020. You can also learn about the complimentary and soon to be expanded offers at the Digital Fair. Don’t forget to sign-up for the free Newsletter mailings. 

•     09.-10. December 2020      DIGITAL FAIR  Trends Winter 2022/23 

 

UPDATE
CoVid-19 continues to keep the world on edge. Many PERFORMANCE DAYS visitors, as well as exhibitors, have already announced that travelling to Munich in December would be simply impossible for them. Due to the increasing number of infections, further international travel bans and company-internal travel restrictions are now threatening. As a result, the December 2020 edition of PERFORMANCE DAYS will unfortunately not take place at the Messe München, but as Digital Fair! On the planned dates of December 09-10, both approved and advanced new tools will go online and provide further proof of PERFORMANCE DAYS’ expansion of its pioneering role in creating a digital textile trade fair experience.