Influence of low molecular weight tail of polypropylene resin on the pore structure by room‐temperature stretching
Influence of low molecular weight tail of polypropylene resin on the pore structure by room‐temperature stretching
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DOI：
10.1002/pen.23527
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发表时间：
2013-12
影响因子：
3.2
通讯作者：
Lei Caihong;Wu Shuqiu;Xu Ruijie;Peng Xinlong;Shi Wen-qiang;H. Bing
中科院分区：
文献类型：
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作者：
Lei Caihong;Wu Shuqiu;Xu Ruijie;Peng Xinlong;Shi Wen-qiang;H. Bing
采用两种重均相对分子质量和z均相对分子质量相近、但低相对分子质量尾部含量不同的聚丙烯树脂制备基于熔融拉伸机理的微孔膜。制备了具有排核晶体结构的前驱体薄膜、退火膜和冷拉伸膜，并对其进行了表征。研究发现，低分子量尾的存在导致前驱体薄膜的片层厚度增加，并在热处理过程中生长出更完整的结晶部分。在室温拉伸过程中，在应力-应变曲线的塑性区内，这些生长的部分被拉出并转化为连接分离的片层的桥梁。低相对分子质量拖尾的冷拉伸膜中连接桥含量较高。此外，低相对分子质量尾部的聚丙烯树脂在应力-应变曲线上表现出更明显的应变硬化行为，表明拉伸的连接链发生了结晶，导致连接桥更稳定，形成的孔结构恶化较少。由此可见，对于具有一定高分子链的聚丙烯树脂，在拉伸制备微孔膜的过程中，低分子量尾的存在对孔结构的形成和稳定具有重要意义。波兰姆。英语。科学，53：2594-2602,2013。©2013塑料工程师学会
Two polypropylene resins with approximate weight-average and z-average molecular weight but differing in low molecular weight tail content were used for the fabrication of microporous membrane based on melt-stretching mechanism. The precursor film with row-nucleated crystalline structure, annealed film and cold-stretched film were prepared and characterized. It was found that the existence of the low molecular weight tail resulted in higher lamellar thickness in precursor film and more perfect grown crystalline part during annealing. During stretching under room temperature, within the plastic region in stress–strain curve, these grown parts were pulled out and converted to bridges connecting separated lamellae. Higher content of connecting bridges existed in the cold-stretching film with low molecular weight tail. In addition, the polypropylene resin with low molecular weight tail showed more pronounced stain-hardening behavior in stress–strain curve, indicating crystallization occurrence of stretched tie chains, resulting in more stable connecting bridges and less deterioration to formed pore structures. Therefore, it can be seen that for polypropylene resin with certain high molecular weight chains, the existence of low molecular weight tail is important to the formation and stabilization of pore structure during the fabrication of microporous membrane by stretching. POLYM. ENG. SCI., 53:2594–2602, 2013. © 2013 Society of Plastics Engineers