Advancing Elastane Separation from Blended Textiles with Roll-to-Roll Chitosan Coating

Elastane, a polyurethane-polyurea copolymer fiber, is renowned for its exceptional elasticity, strength, and chemical resistance, making it a popular choice in blended textiles. Although elastane typically constitutes only about 1% of fabric composition, it is found in approximately 80% of discarded garments in the United States. The core-spun structure of elastane, with its filaments encased in yarn plies of other materials like polyamide or nylon, combined with its strong adhesion and resistance to organic solvents. This complexity poses significant challenges to the implementation of large-scale recycling infrastructure. Here we present a scalable manufacturing method to selectively coat elastane fibers with a dissolvable biopolymer layer, enhancing their separation from blended textiles. Chitosan is an abundant water-resistant polysaccharide and is coated onto elastane fibers in a roll-to-roll process. We demonstrate the effectiveness of this pilot-scale dip coating process, examining the influence of parameters such as bath concentration and viscosity on coating thickness and morphology. Additionally, we explore the chemical interactions between chitosan and elastane, correlating these interactions with adhesion and tensile properties. We also assess the selective redissolution of chitosan in mild acidic conditions, facilitating the efficient separation of coated elastane fibers from other textile components through chemical recycling methods. Our findings provide a promising approach to improving elastane recycling and address a critical challenge in sustainable textile management.