Liquid-liquid phase separation in a polyethylene blend monitored by   crystallization kinetics and crystal-decorated phase morphologies

doi:10.1016/j.polymer.2008.12.028

CORC > 北京大学 > 化学与分子工程学院

	Liquid-liquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies
	Wang, Shujun ; Wu, Changjiang ; Ren, Min-Qiao ; Van Horn, Ryan M. ; Graham, Matthew J. ; Han, Charles C. ; Chen, Erqiang ; Cheng, Stephen Z. D.
刊名	polymer
	2009
关键词	Polyolefin blends Liquid-liquid phase separation Crystallization SMALL-ANGLE NEUTRON CHAIN-BRANCHED POLYETHYLENES POLYMER BLENDS MOLECULAR SEGREGATION LINEAR POLYETHYLENE POLYOLEFIN BLEND GROWTH-RATES SOLID-STATE MELT SCATTERING
DOI	10.1016/j.polymer.2008.12.028
英文摘要	A series of polyethylene (PE) blends consisting of a linear high density polyethylene (HDPE) and a linear low density polyethylene (LLDPE) with an octane-chain branch density of 120/1000 carbon was prepared at different concentrations. The two components of this set of blends possessed isorefractive indices, thus, making it difficult to detect their liquid-liquid phase separation via scattering techniques. Above the experimentally observed melting temperature of HDPE, T(m) = 133 degrees C, this series of blends can be considered to be in the liquid state. The LLDPE crystallization temperature was below 50 degrees C; therefore, above 80 degrees C and below the melting temperature of HDPE, a series of crystalline-amorphous PE blends could be created. A specifically designed two-step isothermal experimental procedure was utilized to monitor the liquid-liquid phase separation of this set of blends. The first step was to quench the system from temperatures of known miscibility and isothermally anneal them at a temperature higher than the equilibrium melting temperature of the HDPE for the purpose of allowing the phase morphology to develop from liquid-liquid phase separation. The second step was to quench the system to a temperature at which the HDPE could rapidly crystallize. The time for developing 50% of the total crystallinity (t(1/2)) was used to monitor the crystallization kinetics. Because phase separation results in HDPE-rich domains where the crystallization rates are increased, this technique provided an experimental measure to identify the binodal curve of the liquid-liquid phase separation for the system indicated by faster t(1/2). The annealing temperature in the first step that exhibits an onset of the decrease in t(1/2) is the temperature of the binodal point for that blend composition. In addition, the HDPE-rich domains crystallized to form spherulites which decorate the phase-separated morphology. Therefore, the crystal dispersion indicates whether the phase separation followed a nucleation-and-growth process or a spinodal decomposition process. These crystal-decorated morphologies enabled the spinodal curve to be experimentally determined for the first time in this set of blends. (C) 2008 Elsevier Ltd. All rights reserved.; Polymer Science; SCI(E); EI; 13; ARTICLE; 4; 1025-1033; 50
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/246520]
专题	化学与分子工程学院
推荐引用方式 GB/T 7714	Wang, Shujun,Wu, Changjiang,Ren, Min-Qiao,et al. Liquid-liquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies[J]. polymer,2009.
APA	Wang, Shujun.,Wu, Changjiang.,Ren, Min-Qiao.,Van Horn, Ryan M..,Graham, Matthew J..,...&Cheng, Stephen Z. D..(2009).Liquid-liquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies.polymer.
MLA	Wang, Shujun,et al."Liquid-liquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies".polymer (2009).