Optimization of hot drawing process of ultra‐high molecular weight polyethylene monofilament prepared by melt spinning

Abstract

AbstractUltra‐high molecular weight polyethylene monofilament is prepared by melt spinning. Differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and tensile testing are used to characterize the crystallinity, crystal form, surface morphology, and tensile strength of the monofilament at various draw temperatures and ratios, as well as the interaction between them. The lamellar crystal structure in the fiber is stable at lower draw temperatures, and an excessive draw ratio will aggravate the stress concentration of the intergranular molecular chain in the drawing process, which can easily lead to microfiber fracture. Increasing the draw temperature encourages not only molecular chain disentanglement in the amorphous region of the fiber, but it can also weaken the crystal structure constraint on molecular chain activity, promote the transformation of lamellar structure into extended chain structure, and improve the loadable draw ratio. The elevated draw ratio drives the orientation of the molecular chain, the crystal structure is motivated to draw along the axis, and the crystal grains are refined, resulting in a more compact internal structure of the fiber. Excessive temperature causes drastic changes in the internal structure of the fiber, which is detrimental to improving draw ratio and fiber strength.