超拉伸UHMWPE纤维的结晶结构及其形成机理

采用冻胶纺丝-超拉伸技术纺制了超高相对分子质量聚乙烯(UHMWPE)纤维。利用小角X光散射(SAXS)、广角X射线衍射(WAXD)及拉曼光谱等测试手段,研究了拉伸过程中UHMWPE纤维的结晶结构变化。结果表明:随拉伸的进行,纤维非晶区中分子链逐渐参与了结晶,纤维SAXS强度减弱,纤维结构变得紧密规整;纤维结晶长周期及结晶度随拉伸倍数的增加而增大,并趋于平衡,拉伸30倍后,纤维结晶长周期约为50 nm,结晶度约为67.5％;纤维横向晶粒平均尺寸随拉伸倍数的增加而变小,拉伸30倍后,趋于平衡,而纤维晶粒c轴方向的轴向晶粒尺寸随拉伸倍数的增加而变大。

Crystalline structure and formation mechanism of ultra-drawn UHMWPE fiber

Ultrahigh molecular weight polyethylene ( UHMWPE) fiber was prepared by gel spinning and ultra-drawing technology. The change of the crystalline structure of UHMWPE fiber was studied by small angle X-ray scattering (SAXS) , wide angle X-ray diffraction ( WAXD) and Raman spectroscopy. The results showed that the molecular chains in amorphous region participated in crystallization gradually, the SAXS intensity became weak, and the structure of the fibers became dense and regular during ultra-drawing. The crystallization long period and the crystallinity of the fibers increased with the draw ratio and tended to achieve equilibrium about 50 nm and 67. 5% at draw ratio of 30, respectively. The transverse crystal average size was decreased with draw ratio and tended to achieve equilibrium at draw ratio above 30 when the c -axial crystal size was increased during ultra-drawing.