PMDA扩链对PET流变性能及发泡性能的影响

Foaming Performanc and Rheological Properties of Chain Extended Polyethylene Terephthalates with PMDA

为了改善聚对苯二甲酸乙二醇酯（PET）的流变性能，提高其发泡性能，以均苯四甲酸二酐（PMDA）对PET进行了熔融扩链改性，采用动态旋转流变仪表征扩链改性PET的流变性能。并利用间歇发泡装置，对扩链改性PET进行超临界流体发泡实验。研究了不同含量扩链剂的扩链效果，以及不同的发泡温度对PET扩链体系泡沫结构的影响。结果表明：PMDA的加入能够有效改善PET的弹性模量和复数黏度，PMDA质量分数为0．75％时，扩链效果最佳，PMDA质量分数为1％时发泡倍率更大。PMDA的添加能够有效拓宽发泡温区，随着发泡温度的升高，PET泡沫发泡倍率先增大后减小。在264℃时，实验制得发泡倍率为21倍、泡孔直径为46～50μm、泡孔密度为2．64×10^8～2.83×10^8个／cm^3的低密度PET泡沫。

In order to improve the rheological properties and foam-ability of polyethylene terephthalates （PET）, pyromellitic dianhydride （PMDA） was used as chain extender to increase the molecular weight of PET and induce long chain branching structure. Dynamic rheometer was used to investigate the rheological properties. The batch foaming processes by supercritical fluids of PET modified with PMDA had been studied. The effect of PMDA concentration and temperature on cell morphology was investigated. As a result, PMDA could improve G＇ and η＊. The best extended PET obtained with 0.75% PMDA, but when the concentration of PMDA was 1.0% , the expansion ration of PET foam was even higher. PET modified with PMDA could broaden the foaming window. As the temperature rose the expansion ration raised , and then decreased. The high expansion ration （ 21 ） , small cell diameter （ 46 - 50 μm ） and high cell density （ 2.64-10^8 - 2.83×10^8/cm^3 ） PET foam was obtained with tempter at 264 ~C.