Continuously spun biocomposite fibers from feather keratin and chitin with better toughness than wool via enhanced protein unfolding and conformation organization

We utilize chitin nanoparticles with controlled deacetylation and develop novel wet-spun keratin/chitin fibers on a pilot scale with strong interactions between keratin fibers and chitin nanoparticles. There is an urgent need to develop sustainable and degradable materials as alternatives to the current nondegradable textile fibers. Regenerating feather wastes into high-quality protein fibers promotes the sustainable development of the fiber industry. However, inferior properties of keratin fibers, resulting from insufficient protein unfolding, molecular entanglements, and recovery of secondary protein structures, hindered their large-scale commercialization. Inspired by chitin-protein interaction in crab shells, we reported the development of wet stable keratin composite fibers with similar fineness to silk and better toughness than wool. On the continuous spinning line, small amount of chitin nanoparticles with controlled amine content enhanced keratin molecular entanglement, improved fiber drawability, induced the formation of ß-sheet conformation, and incorporated external crosslinkages. As a result, keratin composite fibers with chitin nanoparticles had fineness, tenacity, breaking elongation, and toughness, and wet properties from 2.1 to 0.9 denier, 1.1 to 2.2 g/den, 11 % to 19 %, 21 to 50 J/cm3, and 0.6 to 1.2 g/den, respectively. We further fabricated the continuously spun keratin composite fibers into filament yarns and a sweater. Keratin composite fibers exhibited excellent processibility throughout the entire garment-making process. The green conversion from feather wastes to tough and wet stable composite fibers had a high potential for practical and sustainable applications in the textile industry.