烯烃嵌段共聚物的多重分级研究

Study on Olefin Block Copolymer by Multiple Fractionations

综合采用升温淋洗分级(pTREF)和相对分子质量分级(pMMF)的方法将烯烃嵌段共聚物(OBC)分别制备分级为支化度分布较窄的级分和相对分子质量分布较窄的级分。利用高温凝胶渗透色谱(HT-GPC)、结晶淋洗分级(CEF)、差示扫描量热仪(DSC)等进一步分析了基体树脂及其相应的pTREF和pMMF组分的链结构及组成信息。结果表明,多重分级是一种产生OBC样品集的有效方法,该样品集可由相对分子质量相似和支化结构不同的级分,或者支化结构相似但相对分子质量不同的级分构成。进而综合多种分析表征技术对这些交叉分级所得级分进行研究,深入了解了OBC样品分子链结构的非均匀性。

To make a comprehensive analysis, preparative temperature rising elution fractionation(pTREF) and preparative molar mass fractionation(pMMF) are adopted to fractionate the olefin block copolymers(OBC) into fractions with narrower branching and molar mass distributions, respectively. The chain structure and composition of the bulk resins as well as the corresponding pTREF and pMMF fractions are further analyzed by means of gel permeation chromatography, crystallization elution fractionation, and differential scanning calorimetry. The results indicated that the multiple fractionations are a type of powerful approach to generate a library of OBC samples. Such a library can be composed by the fractions with similar molar masses but different branching structures or by the fractions with similar branching but different molar masses. Furthermore, the cross-fractionation was performed for these sample libraries by comprehensive analytical techniques to provide in-depth information on the molecular heterogeneity of OBC samples.