文献类型：期刊文献

英文题名：Investigation of extensional rheological behaviors of polypropylene for foaming

作者：Xu, Zhixin[1];Zhang, Zhuang[1];Guan, Yong[1];Wei, Dafu[1];Zheng, Anna[1]

机构：[1]E China Univ Sci & Technol, Shanghai Key Lab Adv Polymer Mat, Key Lab Ultrafine Mat, Minist Educ,Sch Mat Sci & Engn, Shanghai 200237, Peoples R China

年份：2013

卷号：49

期号：4

起止页码：317

外文期刊名：JOURNAL OF CELLULAR PLASTICS

收录：;EI(收录号：20132716473805);WOS:【SCI-EXPANDED(收录号:WOS:000320885700002)】；

基金：The project is supported by the Shanghai Leading Academic Discipline Project (B502) and the Shanghai Key Laboratory Project (08DZ2230500).

语种：英文

外文关键词：Polypropylene; rheology; foams; supercritical carbon dioxide; strain hardening

摘要：This study investigated the relationship between the extensional rheological behaviors and the foamability of polypropylenes (PPs). Both the shear and extensional rheological properties of four types of PPs with different molecular structures (linear PP, linear PP with high-molecular component, long-chain-branched PP, and cross-linked PP) were tested by rheometers and the PPs were foamed by batch process with supercritical carbon dioxide as foam agent. It was found that when the PP showed strain-hardening behavior at certain strain rates (on the order of 1s(-1)), the obtained foams had high expansion ratio and fine cell structures. Otherwise, the strain-hardening behavior of PP had limited effects on the foamability. In addition, a theoretical analysis suggested that the strain-hardening behavior provided higher melt strength and simultaneously changed the rupture behavior of the melt, thus the gas bubble could be stable during expansion step and the cellular structure was generated. The foamability of PPs can be predicted from the extensional properties without considering their molecular structures.