Cast films, based on β-iPP, were prepared via melt extrusion, and, then annealed at different temperature. The effect of annealing on the properties of the cast films, as well as on microvoid formation and evolution was investigated. After annealing, the initial lamellar structure was improved, and more secondary crystals were formed which decreased the numbers of tie chains, which was beneficial to cavitation. And the stability of β-crystal and β lamellar thickness distribution was improved. Finally, the membrane obtained by unannealed film had inferior pore-size distribution, while the annealed sample had uniform pore-size distribution.

中文翻译：

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退火对β成核全同立构聚丙烯双轴拉伸过程中微孔形成和演化的影响

通过熔融挤出制备基于β-iPP的流延膜，然后在不同温度下退火。研究了退火对流延膜性能以及微孔形成和演变的影响。退火后，改善了最初的层状结构，并形成了更多的次生晶体，从而减少了键链的数量，有利于空化。并提高了β晶体的稳定性和β层状厚度分布。最后，通过未退火的膜获得的膜具有较差的孔径分布，而经退火的样品具有均一的孔径分布。