Blending recycled poly(lactic acid) (PLA) with elastane recovered from textile fibers: A sustainable valorization approach

The recycling of elastane from textile waste and its reintegration into polymeric matrices represents a possible pathway towards the achievement of a real circular economy in the textile industry. This study investigates the dissolution and recovery of elastane using environmentally friendly solvents and its subsequent blending with recycled poly(lactic acid) (PLA). Among tested solvents, dimethyl sulfoxide (DMSO) was the most effective, dissolving elastane at 120 °C with a solubility limit of 40.77 mg EL/g DMSO at 160 °C. Recovery via non-solvent induced phase separation (NIPS) allowed for 75–80 % solvent recovery, with residual DMSO reduced down to 5–6 % after drying. Blends of recycled PLA with recovered elastane (5–15 wt.%) were produced via melt extrusion and evaluated for mechanical and thermal properties. Tensile tests revealed that adding elastane reduced the elastic modulus (from 3.52 GPa for PLA to 3.14 GPa for PLA+15) while increasing elongation at break. However, tensile strength declined due to poor interfacial adhesion between PLA and elastane. Dynamic mechanical thermal analysis (DMTA) confirmed elastane's limited compatibility with PLA, showing separate glass transition temperatures at ∼60 °C (PLA) and ∼10 °C (elastane). Differential scanning calorimetry (DSC) indicated an increase in PLA crystallinity (from 19.5 % for PLA to 24.9 % for PLA+5), followed by stabilization around 20.7 % at higher elastane content. Scanning electron microscopy (SEM) revealed elastane dispersion within the PLA matrix, with droplet coalescence at higher elastane concentrations. Despite its limited compatibility, this study highlights the potential for elastane to have a second life and demonstrates the feasibility of incorporating it into recycled PLA. It lays the foundation for future research on compatibilization strategies to improve mechanical performance.