Effects of Drawing Conditions on Improving Fiber Properties of Melt‐Spun High‐Density Polyethylene/Ultrahigh‐Molecular‐Weight Polyethylene Fibers

ABSTRACT In this study, the drawing conditions of melt‐spun high‐density polyethylene (HDPE)/ultrahigh‐molecular‐weight polyethylene (UHMW‐PE) fibers were investigated to improve their mechanical properties and fiber diameter. An as‐spun HDPE/UHMW‐PE blended fiber containing 30 wt% UHMW‐PE was prepared by melt spinning. The PE fiber with a high tensile strength of approximately 2.0 GPa was produced by drawing the as‐spun fiber at 120°C. This strength was significantly higher than that of previous PE fibers produced by melt spinning. Additionally, a two‐step drawing process was also developed to reduce the fiber diameter and increase the strength simultaneously. First, pre‐drawing was performed in the molten state at 145°C and a low strain rate. Then, the obtained pre‐drawn fiber was drawn at 130°C and a high strain rate. The total draw ratio was higher in the two‐step drawing process, resulting in the improved degree of thinning. Lowering the draw ratio during pre‐drawing increased the draw ratio during the second drawing, resulting in improved tensile strength. Consequently, the PE fiber with both a smaller diameter (approximately 20 μm) and a higher strength (approximately 1.6 GPa) was produced by the two‐step drawing process.