Porous, Water-Resistant Multifilament Yarn Spun from Gelatin

Sustainability, renewability, and biodegradability of polymeric material constantly gain in importance. A plausible approach is the recycling of agricultural waste proteins such as keratin, wheat gluten, casein or gelatin. The latter is abundantly available from animal byproducts and may well serve as building block for novel polymeric products. In this work, a procedure for the dry-wet spinning of multifilament gelatin yarns was developed. The process stands out as precipitated gelatin from a ternary mixture (gelatin/solvent/nonsolvent) was spun into porous filaments. About 1000 filaments were twisted into 2-ply yarns with good tenacity (4.7 cN tex(-1)). The gelatin yarns, per se susceptible to water, were cross-linked by different polyfunctional epoxides and examined in terms of free lysyl amino groups and swelling degree in water. Ethylene glycol diglycidyl ether exhibited the highest cross-linking efficiency. Further post-treatments with gaseous formaldehyde and wool grease (lanolin) rendered the gelatin yarns water-resistant, allowing for multiple swelling cycles in water or in detergent solution. However, the swelling caused a decrease in filament porosity from similar to 30% to just below 10%. To demonstrate the applicability of gelatin yarn in a consumer good, a gelatin glove with good thermal insulation capacity was fabricated.