Effect of UHMWPE concentration on the extracting, drawing, and crystallizing properties of gel fibers

In this study, ultra-high molecular weight polyethylene (UHMWPE) gel fibers were made by gel-spinning with different concentration solutions of 8–16 wt%. The solvent separation and extracting dynamics of different gel fibers were studied. The thermal and crystallizing properties of different fibers were characterized with differential scanning calorimeter and wide-angle X-ray diffraction. The morphological structure of different gel fibers was observed using scanning electron microscope (SEM). The maximum drawing ratios (DRs) of different fibers and the tenacity of ultra-drawn fibers were measured and compared. The results showed that the phase separation of different concentration UHMWPE gel fibers were severe at the first hour and reached equilibrium state after about 48 h placing. The critical extraction time of different gel fibers and the optimum bath ratios of extraction agent to gel fibers were 2 min and 10 mL/g, respectively. The melting point and the crystallinity of extracted fibers were both higher than that of gel fibers, and the crystallinity of fibers increased with increasing of UHMWPE concentration. High concentration UHMWPE fiber has more dense morphological structure while compared with lower concentration ones. The maximum achieved DRs of gel fibers were higher than that of extracted fibers. The DR and tensile strength of extracted fibers decreased with increasing of UHMWPE concentration.