Upcycling of Keratin Wastes in Sustainable Textile Fiber Applications

The textile industry is facing growing pressure to adopt sustainable practices, including the development of biodegradable and recyclable fibers derived from waste streams. In this study, we explored the use of keratin from waste textiles as a potential raw material for sustainable fiber production. We investigated the dissolution of keratin in 7-methyl-1,5,7-triazabicyclo(4.4.0)dec-5-ene (mTBD)-based ionic liquids (ILs) and its regeneration in various coagulation solvents. The viscoelastic properties of the keratin solution were characterized using small angle oscillation shear rheology (SAOS), and the results showed that the keratin solution was not suitable for the dry-jet spinning process and the pure regenerated keratin fiber was too weak to hold the stretching in fiberline. To bypass these issues, we blended high molar mass cellulose with keratin during the dissolution step to adjust the rheological properties and mechanical strength of the extruded fibers. The resulting hybrid fibers exhibited high strength, low fibrillation tendency, and soft texture. We also demonstrated the further processability of these fibers by spinning a yarn and knitting a piece of fabric. Our findings suggest that hybrid fibers derived from keratin waste textiles and cellulose could be promising materials for sustainable fashion applications.