Effects of long chain branches on the crystallization and foaming behaviors of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers with well-defined molecular structures

doi:10.1016/j.polymer.2012.08.036

CORC > 化学研究所 > 中国科学院化学研究所

	Effects of long chain branches on the crystallization and foaming behaviors of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers with well-defined molecular structures
	Wang, Lu 1,2; Wan, Dong 1,2; Qiu, Jian 1; Tang, Tao 1
刊名	POLYMER
	2012-09-28
卷号	53 期号:21 页码:4737-4757
关键词	Polypropylene (Pp) Long Chain Branch Crystallization Kinetics
ISSN号	0032-3861
DOI	10.1016/j.polymer.2012.08.036
英文摘要	A series of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers (PP-g-EBR) with well-defined long chain branched (LCB) molecular structures, basing on the same PP-BT precursor (PP-BT2), were used to study effects of EBR LCBs on the crystallization and foaming behaviors of PP-g-EBRs. The kinetics results of isothermal and nonisothermal crystallization verify the opposite effects of LCB structure on the crystallization process of PP backbones in PP-g-EBRs: on one hand, the indolent LCB structure can perform the function of heterogeneous nucleation to facilitate the crystallization: on the other hand, the mobility and reptation ability of PP backbones are restrained by the LCB structure, which hinders the crystallization process. Additionally, the fluctuation-assisted nucleation mechanism caused by microphase separation between the EBR rich phase and the PP rich phase may account, to some extent, for the heterogeneous nucleation effect. The PP-BT2 and PP-g-EBRs were foamed by a batch method under the same conditions, using supercritical CO2 as blowing agent. The resulting PP-g-EBR foams exhibited closed cell structure and increased cell density compared to the PP-BT2 foam, attributing to the enhanced melt strength. The cell density of PP-g-EBR foam increased first and decreased then with the LCB level increasing. The influence of LCB level on cell size was somewhat complex. Increasing LCB level, which promoted melt strength and strain hardening behavior of PP-g-EBRs, decreased the cell size and narrowed the cell size distribution. However, large cells were observed in PP-g-EBR foams with relatively high LCB level, which could be ascribed to the larger growing space introduced by the higher content of amorphous EBR LCBs. Moreover, the melting behaviors of PP-BT2 and PP-g-EBRs before and after foaming treatment were compared. (C) 2012 Elsevier Ltd. All rights reserved.
语种	英语
出版者	ELSEVIER SCI LTD
WOS记录号	WOS:000309377400022
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/49689]
专题	中国科学院化学研究所
通讯作者	Tang, Tao
作者单位	1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Peoples R China 2.Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China
推荐引用方式 GB/T 7714	Wang, Lu,Wan, Dong,Qiu, Jian,et al. Effects of long chain branches on the crystallization and foaming behaviors of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers with well-defined molecular structures[J]. POLYMER,2012,53(21):4737-4757.
APA	Wang, Lu,Wan, Dong,Qiu, Jian,&Tang, Tao.(2012).Effects of long chain branches on the crystallization and foaming behaviors of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers with well-defined molecular structures.POLYMER,53(21),4737-4757.
MLA	Wang, Lu,et al."Effects of long chain branches on the crystallization and foaming behaviors of polypropylene-g-poly(ethylene-co-1-butene) graft copolymers with well-defined molecular structures".POLYMER 53.21(2012):4737-4757.