Environmental Sustainability Assessment of Supercritical CO2 in Gel-Spun Ultrahigh Molecular Weight Polyethylene Fiber Production

Abstract

Ultrahigh 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, across 17 midpoint indicators. The new scCO₂-based process (scCO₂W) enables the recovery and reuse of CO₂ and residual mineral oil from gel spinning. Comparative results indicated that scCO₂W outperforms conventional hexane-based washing (HW) in 13 categories, including a 2.4-fold reduction in the 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 GWP 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.