Structural Evolution of UHMWPE Fibers during Poststretching with Distinct Initial Structures

By adopting a homemade extension apparatus and wide-angle X-ray diffraction (WAXD) technique, the structural evolutions of the extracted ultra-high molecular weight polyethylene (UHMWPE) fibers with different spinning draw ratios were investigated during the poststretching process. Molecular chains oriented along the axis quickly at the early stage of drawing, which is quite different from the situation of drawing with solvents. The crystal regions, which have not melted at higher temperature, show stronger rigidity in the absence of solvents. Rigid characteristics show faster response to the external field. Also, the surface morphologies of fibers after poststretching are characterized by scanning electron microscopy (SEM). The lamellae stack disordered before stretching, but arranged in order along the draw direction when the draw ratios were larger than 1.