Structure and properties evolution of UV crosslinked ultra-high molecular weight polyethylene fiber during processing

With the development of heat and creep-resistant UHMWPE fiber via UV crosslinking, its structure-properties evolution during processing needs attention. The structures of UHMWPE fiber in different forms, the pre-oriented yarn (POY), the full stretch yarn (FDY) and UV crosslinked FDY (UVFDY), obtained from our pilot line were systematically studied with differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and solid-state C-13 NMR. Additionally, the heat and creep resistance of UVFDY were evaluated by the temperature at break (T-b), glass transition temperature (T-g), time at break (t(b)) for a given aging temperature, and creep elongation (L-c). The results demonstrated that UVFDY possessed high gel content (89.0%), high crystallinity (84.2%), and high orientation (91.7%). These characteristics caused UVFDY not only with excellent mechanical properties but also process extraordinary heat and creep resistance, especially for its much higher T-b (220 degrees C), T-g (-75.7 degrees C) and t(b) (20 h) while lower L-c (7.8%), comparing with FDY (T-b = 158 degrees C, T-g = -86.8 degrees C, t(b) = 1.3 h and L-c = 38.2%). This work provides insights into the structure-properties relationship of UVFDY, which will aid in the development of UV crosslinked UHMWPE fiber with better heat and creep resistance.