The influence of entanglement degree controlled by complex shear field on the performance of long-chain branched polypropylene

IF 3.5 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Materials Science Pub Date : 2024-11-09 DOI:10.1007/s10853-024-10374-4

Mengna Luo, Mingjin Liu, Zheng Yan, Tao Wang, Yabing Qian, Jie Zhang

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Abstract

The entanglement of polymers can cause a sharp increase in the viscosity of polymer melt, which is adverse to polymer processing. Disentanglement is an effective method to improve the processing performance of polymers without sacrificing mechanical properties. Although there are some methods to reduce the entanglement degree of polymers, few methods can preserve the disentangled state in pellets for secondary processing. Long-chain branched polypropylene (LCB-PP) has a slower entanglement recovery rate due to its branched chain. Thus, it is worth studying whether the disentangled state of LCB-PP can be kept in pellets to improve processing performance during secondary processing. In this work, disentangled LCB-PP was successfully prepared using the self-designed polymer melt disentanglement device that can apply a complex shear field (a superposition of rotational shear and oscillatory shear) to polymers. The effect of the rotational shear, oscillatory shear, and complex shear on disentanglement was studied. The results show that the complex shear field has a better effect on the disentanglement of LCB-PP, which is endowed with lower viscosity and higher melt flow rate compared to rotational shear and oscillatory shear. In secondary processing, the processing temperature and injection pressure required for disentangled LCB-PP are significantly reduced while mechanical properties are maintained.

Graphical abstract

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复杂剪切场控制的缠结度对长链支化聚丙烯性能的影响

聚合物缠结会导致聚合物熔体粘度急剧上升，不利于聚合物加工。解除缠结是在不牺牲机械性能的前提下改善聚合物加工性能的有效方法。虽然有一些方法可以降低聚合物的缠结度，但很少有方法可以在颗粒中保留解缠状态，以便进行二次加工。长链支化聚丙烯（LCB-PP）由于其支化链，缠结恢复速度较慢。因此，在二次加工过程中，能否在粒料中保留 LCB-PP 的分散状态以提高加工性能值得研究。在这项工作中，使用自行设计的聚合物熔体解缠装置成功制备了解缠 LCB-PP，该装置可对聚合物施加复合剪切场（旋转剪切和振荡剪切的叠加）。研究了旋转剪切、振荡剪切和复合剪切对解缠的影响。结果表明，与旋转剪切和振荡剪切相比，复合剪切场对具有较低粘度和较高熔体流动速率的 LCB-PP 的解缠效果更好。在二次加工中，解缠 LCB-PP 所需的加工温度和注射压力显著降低，同时机械性能得以保持。

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来源期刊

Journal of Materials Science 工程技术-材料科学：综合

CiteScore

7.90

自引率

4.40%

发文量

1297

审稿时长

2.4 months

期刊介绍： The Journal of Materials Science publishes reviews, full-length papers, and short Communications recording original research results on, or techniques for studying the relationship between structure, properties, and uses of materials. The subjects are seen from international and interdisciplinary perspectives covering areas including metals, ceramics, glasses, polymers, electrical materials, composite materials, fibers, nanostructured materials, nanocomposites, and biological and biomedical materials. The Journal of Materials Science is now firmly established as the leading source of primary communication for scientists investigating the structure and properties of all engineering materials.