Slaughterhouse waste could be made into yarn

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Samples of the collagen yarn(Credit: ETH Zurich)

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Ever since the late 19th century, people have experimented with making textiles from natural-source-based gelatine, as a cheaper and less allergenic alternative to wool. Although the emergence of synthetic fibers largely put an end to that, a new technique may yet allow gel-based yarn to see the spotlight. The fiber is said to have an insulation quality similar to that of Merino wool, and the collagen used to produce it can be obtained from waste at animal-processing facilities.

The process was developed by Philipp Stössel, a student at Switzerland’s ETH Zurich research institute, who collaborated with colleagues from the Advanced Fibers Laboratory at Empa St. Gallen.

To begin, animal waste products such as skin, bone and tendons are obtained from a slaughterhouse. Collagen is rendered from them, and converted to an aqueous gel. When that gel is heated and isopropyl solvent is added, proteins in the collagen precipitate at the bottom of the solution.

That precipitate is removed and then extruded into fine "endless" filaments, using a row of syringes. The filaments run over rollers that sit in an ethanol bath (seen below), the ethanol coating the filaments and causing them to harden. They are then wound together to form a yarn.

While the finished product is said to have a more lustrous finish than wool, it’s also more water-soluble. In an attempt to remedy that, Stössel has treated the material with epoxy in order to better bond the filaments together, he’s treated it with formaldehyde to get it to harden better, and he’s impregnated it with lanolin to make it more supple.

That said, sheep’s wool still has the edge when it comes to water-resistance, so Philipp is continuing to work on improving that aspect of the material. He and his colleagues are now looking for industrial partners, to commercialize the technology.

Source: ETH Zurich

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