拉伸外场作用下热定型工艺对湿法隔膜微观结构及性能影响关系研究

在湿法隔膜制备过程中,热定型工艺与常规热定型工艺有所不同,在高温处理同时还需要对隔膜进行拉伸回缩,即湿法隔膜在热定型过程中存在拉伸外场和温度场耦合作用.本文通过设计不同拉伸比与回缩比,研究了热定型工艺中拉伸外场(拉伸比、回缩比)对隔膜微观结构及宏观热收缩性能的影响关系.结果 发现,小的拉伸比(≤1.3)仅作用于聚乙烯的...

The Influence of Heat Setting Process on the Microstructure and Performance of Wet-process Separator under the Tensile External Field

In the producing process of wet-process separator,the heat setting process is different from the conventional one,because in addition to the high temperature treatment,the separator also needs to be stretched and retracted.That is,the coupling effect of stretching external field and temperature field act on the wet separator during the heat setting process.In this study,by designing different draw ratios and retraction ratios,the influence of the external stretching field(draw ratio,retraction ratio)on the microstructure and macro thermal shrinkage properties of the separators during the heat setting process is studied.It was found that a small draw ratio(≤1.3)only acts on the amorphous region of polyethylene.As the draw ratio increases,the polyethylene crystals begin to be stretched and destroyed,resulting in the decrease of crystallinity and crystal size.At the same time,increasing draw ratio could enlarge the pore diameter of the wet separator.While the pore diameter of the separator also increases with the retraction ratio,indicating that the fiber fusion and pore enlargement occur during the retraction process.In addition,the increase of the draw ratio and the retraction ratio is beneficial to the release of the internal stress in separator,so that the TD thermal shrinkage of the separator is significantly reduced.