横向拉伸对聚丙烯微孔膜结构与性能的影响

Effect of transverse stretching on structure and properties of polypropylene microporous membranes

摘要:

对单向拉伸聚丙烯（pp）微孔膜的横向方向进行二次拉伸后，利用SEM、DSC等方法研究横向拉伸后微孔膜的微观结构和物理性能，探讨微孔膜透气性、孔径分布等性能与拉伸程度的关系．结果表明，微孔膜经过二次横向拉伸后，微孔膜的MD方向未出现收缩，横向强度均有所提高；DSC曲线上低温平台区逐渐消失，结晶主熔融峰向高温方向移动．当拉伸比超过10，后，微孔膜的微孔分布和排列规整性变差，微孔孔径变大，片晶结构破坏严重，横向收缩明显增加．当横向拉伸为10，时，微孔膜有较好的微观结构，横向强度提高了2．33MPa，横向收缩率仅有2．1，，孔隙率和孔径增加，透气时间缩短．

Abstract:

In this paper ,the microporous membrane was secondary stretched along the transverse direc-tion .The structure and properties of microporous membrane with different transverse stretching ratios were characterized by scanning electron microscope (SEM) ,differential scanning calorimetry (DSC) .The results showed that after the secondary stretching ,the shrinkage phenomenon along the machine direction disappeared and the transverse strength increased .With increasing the stretching ratios ,the endotherm plateau on the DSC curve disappeared and the melt point shifted to high temperature .When the stretching ratio was more than 10， ,the pore distribution and arrangement became worse and the lamellae structure damaged seriously .T he transverse shrinkage significantly increased .Only under the transverse stretching ratio of 10， ,the microporous membrane showed better structure .The transverse stress was improved by 2 .33MPa and the shrinkage percent was only 2 .1， .Meanwhile ,the membrane had the higher porosity and pore diameter .Gurley value was reduced obviously .