Due to low molecular weight and wide molecular weight distribution, polyethylene terephthalate (PET) shows weak melt strength properties. In this study, the synergistic effect of using different types of chain extenders and catalyst on rheological behavior of PET has been investigated. Long‐chain branching is known as a suitable method for developing the structure of PET during reactive melt processing. Thus, pyromellitic dianhydride (PMDA) and pentaerythritol (PENTA) were added to the fiber grade PET. The best formulation was determined based on rheological results, which revealed an improvement in both storage modulus and complex viscosity of PMDA‐modified samples. Samples containing 1.5% PMDA and 0.5% PENTA exhibited the best rheological properties. Also, dibutyltin dilaurate (DBTDL) acted as an accelerator for chain extension reaction during reactive melt blending. Subsequently, the rheological properties were improved by increasing the chain extending rate. Moreover, thermal properties such as crystallization and melting temperatures and the degree of crystallinity for modified PET were investigated by differential scanning calorimetry.

中文翻译：

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均苯四甲酸二酐和季戊四醇扩链剂改性的聚对苯二甲酸乙二醇酯的流变/热性能

由于低分子量和宽分子量分布，聚对苯二甲酸乙二酯（PET）表现出较弱的熔体强度性能。在这项研究中，已经研究了使用不同类型的扩链剂和催化剂对PET流变行为的协同作用。长链支化是在反应性熔体加工过程中开发PET结构的合适方法。因此，将均苯四酸二酐（PMDA）和季戊四醇（PENTA）添加到纤维级PET中。根据流变学结果确定了最佳配方，这表明PMDA改性样品的储能模量和复数粘度都有所改善。含有1.5％PMDA和0.5％PENTA的样品表现出最好的流变性能。也，二月桂酸二丁基锡（DBTDL）在反应性熔融共混过程中充当链增长反应的促进剂。随后，通过增加扩链率来改善流变性能。此外，通过差示扫描量热法研究了改性PET的诸如结晶和熔融温度的热性质以及结晶度。