Environmental Sustainability Assessment of Supercritical CO₂ in Gel-spun Ultra-High Molecular Weight Polyethylene Fiber Production

Ultra-high molecular weight polyethylene (UHMWPE) fibers are high-performance materials typically obtained via gel-spinning, a technique that requires extensive use of organic solvents to wash the produced fibers, posing significant environmental concerns. This study presents a novel washing method employing supercritical carbon dioxide (scCO₂) and evaluates its environmental sustainability, using life cycle assessment (LCA), across 17 midpoint indicators. <br/>The new scCO₂-based process (scCO2W) enables recovery and reuse of CO₂ and residual mineral oil from gel-spinning. Comparative results indicated that scCO_₂W outperforms conventional hexane-based washing (HW) in 13 categories, including a 2.4-fold reduction in global warming potential (GWP). Energy consumption for fiber washing was identified as the main hotspot in scCO₂W, and a sensitivity analysis indicated that switching to renewable electricity sources can lead to a 45% reduction to the estimated GWP. Scenario analysis of alternative solvents showed that hexane performed better than heptane and dichloromethane in most indicators. Evaluation of two end-of-life scenarios for HW showed that incineration with energy recovery is generally more beneficial than solvent recovery; however, the recovery option showed advantages in global warming reduction, with up to 33% lower impact. Finally, scenario analysis of the scCO₂W process highlighted the critical role of CO₂ and mineral oil recovery, suggesting that benefits of scCO₂W are only evident when recovery is ensured. The findings support the adoption of scCO₂W as a more environmentally sustainable alternative for cleaning UHMWPE fibers, with the potential to transform the footprint of current manufacturing processes.