热拉伸的超高分子量聚乙烯的晶体结构和力学性能

讨论了超高分子量聚乙烯（ＵＨＭＷ－ＰＥ）的熔融一次拉伸和二次拉伸的晶体结构和力学性能．利用ＷＡＸＤ和ＳＡＸＤ测定了拉伸片的晶体取向因子和极图，晶粒尺寸，晶体畸变，长周期等晶体结构．用ＤＳＣ和ＶＥＳ测定热性能和动态力学性能．应力－应变实验测定拉伸片的杨氏模量，断裂强度和伸长．这些实验结果说明ＵＨＭＷ－ＰＥ经二次拉伸能产生正交晶系的伸直链晶体．二次拉伸片由折叠链片晶和伸直链晶体两元结构组成．二次拉伸片的杨氏模量比一次拉伸片有大幅度提高．二次拉伸片的晶体结构和力学性能是在一次拉伸的基础上形成的．

CRYSTAL STRUCTURE AND MECHANICAL PROPERTIES OF HOT DRAWN UHMW-PE

he paper discussed the changes of crystal structure and mechanical properties of hot drawn and twice drawn sheets of UHMW-PE in melted state.The crystal orientation of the drawn sheets were tested by using WAXD,the 200 and 020 pole figers were made and the orientation factors fa, fb and fc were calculated.The crystallite and amorphous region size along draw direction were obtainded by measuring the integral breadth of the 002 reflection profile and long period for the drawn sheets.The DSC curves for twice drawn UHMW-PE sheets showed that besides a main peak,a small melt peak was observed at 152--153to. The dynamic mechanical behavious for the hot drawn sheets and twice drawn sheets indicated that β-relaxation appears in lower draw ratio sheets and in higher draw ratio and twice drawn sheets β-relaxation degenerated greatly or disappeared.The Young's modulus of twice drawn UHMW-PE were much higher than the first drawn one.The results showed that twice drawn UHMW-PE sheets had hi-component crystllization:most crystals were folded chain type, a few were extended chain crystals.Structures and properties of twice drawn sheets were improvement of first drawn one.