Stretching-Induced Uniform Micropores Formation: An in Situ SAXS/WAXS Study

• DOI: 10.1021/acs.macromol.7b02335
• Publication Date: 2018-04-26T17:11:37Z
• Authors: Caihong Lei; Ruijie Xu; Ziqin Tian; Henghui Huang; Jiayi Xie; Xingqi Zhu
• Keywords: Small-angle X-ray scattering; Shrinkage

Although the microporous membrane prepared based on melt stretching mechanism has been commercialized for more than 20 years, formation process from initial lamellae structure to final fiber connecting bridges and pores is still unclear. In this work, clarify transformation mechanism, in situ SAXS WAXS were carried out during hot at 130 °C 100%. The scattering patterns annealed film, cold stretched film 20% (stretched room temperature), heating also collected. preparation technology was similar that commercial fabrication. It found many long narrow crazes are formed between separated clusters, a part of destroyed crystals appeared. After °C, oriented needlelike voids appeared, which related shrinkage amorphous chains along transverse direction, due tension stress effect. Also some crystal formed. During 20%, close craze wall rotated as fibril axle among cluster. Further 100%, these transformed bridges, contributed by strain-induced crystallization. whole stretching, machine direction crystallized into bridges. This first time clearly describe membrane.