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Photo: Open source

Converting used wool fibres to artificial silk

Textile industry leaves a considerable footprint on our planet. One reason is its linear economy structure, where new raw materials pass through the production and use phases only to end up on ever-growing landfill sites. Technology development for the circular transition is a major focus in our R&D-labs at the moment.

Wool is a natural fibre offering many excellent qualities such as thermal insulation and moisture absorption. It is also relatively well suited for mechanical recycling, where used fabrics can be shredded back into fibre form and then spun to form new yarns. Unfortunately, this recycling method works less well for blend fabrics where the wool is mixed with synthetic fibres. Fibre blended textiles may instead be recovered through chemical recycling methods, where the wool component is dissolved and then artificially wet-spun to form new filaments. 

This may sound straight forward, but the sophisticated molecular composition that makes up a wool fibre - predominantly protein molecules known as keratin - presents quite a challenge to both the dissolution and the wet-spinning processes. Keratin is a structural protein found in various biological materials, a fact that awakens hope of novel applications for wet-spun keratin fibres. Whether the intended application is as artificial wool, artificial silk or medtech applications, managing to selectively unlock and re-lock the disulfide bonds that create resilient cross-links within the keratin structure, is key to developing tailormade keratin filaments.

Fortunately, this research finds support from engaged partners in textile industry. Says Jenny Odqvist Kristensson, Woolpower: "We are highly motivated to push the industry towards large scale recycling, minimal waste and a circular economy. Ideally we can develop a system where all scraps as well as used products can be re-introduced as raw materials. We already use mechanical recycling for some of our production waste, but more methods are needed."

Franciska Dehler and Camilla Olsson of Filippa K are on board with that vision: "Being able to recycle the highly blended fabrics that are frequently used in our core garments is an ideal scenario for the future. Making use of the newly developed filaments will not be a problem, as long as quality and durability are ensured. We are open to letting the material itself develop the style." Marta Oliveira and Sonia Soares of Paulo de Oliveira, point out that recycling will be a necessity in the near future: "We already have difficulty disposing of our production waste, especially the blend materials, as no one wants to take care of it. Currently we already use a lot of our wool waste to weave thicker carded yarns, but the possibility of recovering the wool and spinning fine yarns opens up a much wider range of possibilities, so our expectations with this project are high."

At Südwolle, Robert Kaminszky offers a different perspective: "Wet spinning of dissolved wool may offer an attractive alternative route to make use of the coarse wool, which is for example typical for Swedish sheep."

I am glad to say that my hard-working colleagues have recently managed to spin a first set of filaments from dissolved wool, and that the research and development is still very much ongoing.

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