Up to now, old clothes made of cotton or mixed cotton fibers have often been burned instead of being recycled into new clothes. But that could change now. Because researchers have succeeded in producing new yarn from recycled cotton fibers. To do this, they remove the pulp from the old clothing and use it to create a viscose yarn. This can then be used to create new, high-quality items of clothing.
Clothing has almost become a disposable item today: T-shirts, trousers and the like are so cheap that many people buy more of them than they need – not a few wardrobes overflow. Often the clothes are thrown away after a short time and replaced with new ones. However, this “fast fashion” leads to social and ecological problems, especially in the producing countries, because the production of clothing requires tons of resources, chemicals and water.
The mix is the problem
A remedy could be – in addition to wearing it for a longer period and reusing it as second-hand goods – consistent recycling. So far, however, this has hardly been possible. Usually only inferior products such as cleaning rags can be made from the textiles, but not new clothes. The reason: The material for pants, shirts and Co. is rarely sorted even with cotton fabrics, but mostly consists of mixed fabrics. “Jeans, for example, always contain a proportion of man-made fibers such as polyester or elastane,” says André Lehmann from the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam. To date, separating these blended fabrics has been technically difficult. “As a rule, cotton clothing is therefore burned or it ends up in the landfill,” says the researcher.
But Lehmann and his team, together with the Swedish company re: newcell, have now managed to recycle cotton textiles in such a way that new yarn can be obtained from them. Viscose fibers made from pure cellulose are made from old jeans and the like. Typically, cellulose synthetic fibers such as viscose, modal or lyocell are made from wood. For this, the cellulose part of the wood is chemically dissolved and this spinning solution is then shaped into fibers. This process is relatively complex: alkalis are first used to break down the chain molecules of the cellulose, then acids and other chemicals in the spinning bath ensure that long fibers are formed again, which are then washed out and dried.
Old clothes are turned into viscose yarn
Lehmann and his colleagues have now adapted this process so that instead of wood, used clothing made from blended fabrics can also be used as a pulp supplier. “However, we received cellulose panels made from recycled cotton from re: newcell and we were asked to check whether they could be further processed into viscose fibers,” reports Lehmann. “By setting the right parameters in the solution and spinning process, such as effective filtration stages, we were able to remove the foreign fibers contained in the pulp.” The result of the new method is a filament yarn, a continuous fiber that is several kilometers long and is made of 100 percent cellulose is qualitatively comparable to wood-based viscose fibers.
The researchers refer to their new recycling yarn as cotton-based cellulose regenerated fiber. It is suitable for mass production in the industrially established viscose process and can therefore be used for textile production on a large scale. “In the future, cotton clothing can be recycled several times and thus contribute to more sustainability in fashion,” says Lehmann. Because the recycled fibers not only use old clothes instead of newly cleared wood as raw material, they are also significantly more environmentally friendly than petroleum-based polyester fibers. Because the viscose thread consists of pure cellulose, it rots in the environment and therefore does not contribute to further plastic waste.
Source: Fraunhofer Society