大连理工大学牛慧团队报道了化学结构对纤维型高密度聚乙烯玻璃体聚集体结构演化的影响。相关研究成果发表在2024年8月21日出版的《中国高分子科学杂志》。

玻璃高分子已成为聚合物材料领域的一个重点研究领域。大多数研究都集中在合成具有多功能动态交联结构的聚合物上，而化学结构对玻璃化物聚集结构的影响，特别是在聚合物加工过程中，仍然没有得到充分的研究。

该研究采用商业马来酸酐接枝高密度聚乙烯（M-g-HDPE）作为基质，己二醇作为交联剂，通过反应挤出和后拉伸工艺容易获得纤维状HDPE玻璃化物。通过化学结构表征、形态观察、热和力学性能研究以及聚集体结构分析，揭示了动态键对纤维状玻璃化物加工过程中聚集结构形成的影响。

HDPE中的少量动态键在熔融挤出和后拉伸过程中限制了PE链的运动，导致PE链的取向较低。然而，由于动态键合和链松弛之间的竞争，高温后拉伸过程中的层状生长和原纤维形成在一定程度上得到了增强。纤维状HDPE玻璃化物的不均匀形态可归因于动态结合带来的更强弹性效应，与聚合结构相比，动态结合在决定纤维状玻璃化物力学性能方面起着更重要的作用。

附：英文原文

Title: A Study on the Impact of Chemical Structure on the Evolution of Aggregate Structure in Fiber-shaped High Density Polyethylene Vitrimer

Author: Bing Wang, Yuan-Chu Gao, Hai Wang, Hui Niu

Issue&Volume: 2024-08-21

Abstract: Vitrimers have emerged as a prominent research area in the field of polymer materials. Most of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures, while the impact of chemical structure on aggregate structure of vitrimers, particularly during polymer processing, remains insufficiently investigated. The present study employed commercial maleic anhydride-grafted-high density polyethylene (M-g-HDPE) as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shaped HDPE vitrimers through a reaction extrusion and post-drawing process. Through chemical structure characterization, morphology observation, thermal and mechanical properties investigation, as well as aggregate structure analysis, this work revealed the influence of dynamic bonds on the formation of aggregate structures during fiber-shaped vitrimers processing. A small amount of dynamic bonds in HDPE restricts the motion of PE chain during melt-extruding and post-drawing, resulting in a lower orientation of the PE chains. However, lamellar growth and fibril formation during post-drawing at high temperature are enhanced to some extent due to the competition between dynamic bond and chain relaxation. The uneven morphology of fiber-shaped HDPE vitrimers can be attributed to the stronger elastic effect brought by dynamic bonding, which plays a more dominant role in determining the mechanical properties of fiber-shaped vitrimers compared to aggregate structure.

DOI: 10.1007/s10118-024-3176-7

Source: https://www.cjps.org/en/article/doi/10.1007/s10118-024-3176-7