Multiple‐step drawing innovative ultrahigh‐molecular‐weight polyethylene fibers modified with bacterial cellulose and scCO₂‐aid

Abstract

Innovative supercritical carbon dioxide (scCO2)‐assisted ultrahigh‐molecular‐weight‐polyethylene (UHMWPE)/modified bacterial cellulose (MBC) as‐spun fibers were found to display substantially lower dynamic transition temperatures than those acquired for scCO2‐assisted UHMWPE or UHMWPE/MBC as‐spun fibers prepared without scCO2‐assistance or incorporation of MBC nanofibers. Multiple‐step drawing methods were first‐time applied to these finely ''relaxed'' scCO2‐assisted UHMWPE/MBC fibers and considerably improved their achievable draw ratios (Dras), orientation factor (fos), and tensile tenacities (σtts). The best five‐step drawn scCO2UHMWPE/MBC fiber displayed a particularly high σtt of 135 g d−1, which was ~35, ~3.75, and ~1.7 fold of σtts acquired for good steel fiber and the most appropriate single‐step drawn scCO2‐assisted UHMWPE and UHMWPE/MBC fibers, respectively. The particularly high Dras, fo, and σtts acquired for the best multiple‐step drawn scCO2‐assisted UHMWPE/MBC fibers is ascribed to their more ''relaxed'' UHMWPE structures, thinner lamellae, and successive increased drawing temperature in the multiple‐step drawing processes.