文献类型：期刊文献

英文题名：A novel strategy for the preparation of long chain branching polypropylene and the investigation on foamability and rheology

作者：Li, Shuzhao[1];Xiao, Miaomiao[2];Guan, Yong[1];Wei, Dafu[1];Xiao, Huining[2];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;[2]Univ New Brunswick, Dept Chem Engn, Fredericton, NB E3B 6C1, Canada

年份：2012

卷号：48

期号：2

起止页码：362

外文期刊名：EUROPEAN POLYMER JOURNAL

收录：;EI(收录号：20120314694992);WOS:【SCI-EXPANDED(收录号:WOS:000300380300012)】；

基金：We thank the support of Shanghai Leading Academic Discipline Project (B502) and Shanghai Key Laboratory Project (08DZ2230500).

语种：英文

外文关键词：Polypropylene (PP); Rheology; Melt grafting; Long chain branches; Foam extrudate

摘要：A novel strategy for introducing long chain branches (LCB) on commercial polypropylene (PP) was described using an extender agent, poly (hexamethylendiamine-guanidine hydrochloride) (PHGH), to couple with glycidyl methacrylate-grafted PP (PP-GMA). The presence of LCB was confirmed by GPC and melt strength measurements in two modified PP samples, MPP-1 and MPP-2. The foamability of LCB PPs and commercially linear PP (EPS) was investigated by foam extrudate. The results showed that the foamability of LCB PPs was significantly improved. To find out the difference in foamability of EPS and LCB PPs, some rheological properties were investigated. In the dynamic shear measurement, it was found that the elastic response of LCB PPs at low frequencies was distinctly enhanced in comparison with that of EPS, implying a presence of a long relaxation time mode that was not revealed in linear PP. The elongational rheology results showed that the strain hardening behaviors of LCB PPs were still intense even at higher strain rate of 1 s(-1); moreover. MPP-2 could sustain larger elongational stress and deformation, which helps to improve the foamability. In step-shear stress relaxation measurements, the fast and slow relaxation processes were observed over the entire ranges of strains, indicating the presence of two different relaxation time modes. Also, the strain dependence of slow damping function became weaker because of the introduction of LCB on linear PP. In addition, it was also found that the rheological behaviors characterizing the long relaxation time mode were further enhanced with the increase of the concentration of PHGH in the melt grafting reactions. (C) 2011 Elsevier Ltd. All rights reserved.