Structural evolution of UHMWPE gel fibers as high degree plasticized system during stretching: An in-situ wide and small angle X-ray scattering study

Abstract

Ultra-high molecular weight polyethylene (UHMWPE) gel fibers filled with high content of plasticization deformed at room temperature were characterized by using in-situ wide-angle X-ray diffraction (WAXD)/small-angle X-ray scattering (SAXS), and ex-situ differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The structural evolution dependence on the plasticization content and stretching speed was stressed. The gel fibers with 96 wt% plasticization exhibited higher orientation than the fibers with 88 wt% plasticization stretched at the same stretching speed. Both gel fibers presented the stretch-induced crystallization as quantified by an increase in crystallinity index. Partial crystallites were found to be induced in the manner of fragmentation-recrystallization accompanied by fibrillization. However, when stretched beyond a threshold strain, the orientation factor, crystallinity index, and long period of both gel fibers changed slowly, which corresponded to the transition from the inability of the structure to continue evolving smoothly. A new mechanism for the structural evolution of high-plasticized UHMWPE gel fibers was proposed to summarize the above results. • The structural evolution in high content plasticized UHMWPE systems was studied. • Effect of degree of plasticization on the structural evolution was compared. • Effect of stretching speed on the structural evolution was compared. • In-situ WAXD/SAXS technique was used for the study.