石油化工2025，Vol.54Issue(11)：1565-1571,7.DOI:10.3969/j.issn.1000-8144.2025.11.003
宽共聚单体分布的线型低密度聚乙烯及其级分结晶的熔体记忆效应
Melt memory effect of crystallization in linear low-density polyethylene with broad comonomer distribution and its fractions
摘要
Abstract
This study investigated linear low-density polyethylene(LLDPE)with broad comonomer distribution synthesized using metallocene catalysts through preparative temperature-rising elution fractionation for both molecular weight fractionation and chemical composition fractionation.The molecular chain architecture,crystallization kinetics,and melt memory effects of fractions were further analyzed by high-temperature GPC,13C NMR,DSC etc.The experimental results reveal that the LLDPE contains a relatively high content of moderately or highly branched molecules.Accordingly,the presence of crystalline seed nuclei in the melt leads to typical melt memory behavior,facilitating rapid nucleation during crystallization.Although molecular weight fractionation achieves separation based on long-range chain structure,the fractions still exhibit a broad comonomer distribution.When the content of highly branched molecules exceeds 15%(x),both melt memory effects and liquid-liquid phase separation(LLPS)are observed.In contrast,chemical composition fractionation,by precisely separating molecular chains with different branching topologies,eliminates the phenomenon of LLPS.Compared to molecular weight fractionation,chemical composition fractionation more effectively separates molecular chains with distinct branching structures,thereby significantly mitigating the impact of LLPS on the crystallization process.关键词
线型低密度聚乙烯/级分/共聚单体分布/结晶/熔体记忆/液-液相分离Key words
linear low-density polyethylene/fraction/comonomer distribution/crystallization/melt memory/liquid-liquid phase separation分类
化学工程引用本文复制引用
罗春霞,任敏巧,刘宣伯,姚雪容,郑俊鹏,侯莉萍..宽共聚单体分布的线型低密度聚乙烯及其级分结晶的熔体记忆效应[J].石油化工,2025,54(11):1565-1571,7.基金项目
中国石化科技开发课题(224148). （224148）
