PET-PTMG聚醚酯降解行为研究

Study on thermal oxidation degradation of PET-PTMG poly(ether-ester)s

采用熔融缩聚法,以对苯二甲酸、乙二醇和聚四氢呋喃(PTMG)为原料,合成了不同PTMG组成的聚对苯二甲酸乙二醇酯(PET)-聚四氢呋喃聚醚酯。通过热失重分析法(TGA),在氮气和空气中对聚醚酯的热降解行为进行了研究。结果发现,聚醚结构的引入降低了聚醚酯的热稳定性,并且对氧气敏感。应用Kissinger方法计算了PET及其聚醚酯在空气中降解的表观活化能,发现PET降解分为两步,活化能分别为179 kJ/mol和148 kJ/mol;而聚醚酯降解为三步,活化能范围为66~97 kJ/mol、196~197 kJ/mol和135~142 kJ/mol。应用Flynn-Wall-Ozawa方法研究显示,聚醚酯在降解初期活化能较低,热稳定性较差;但在反应后期,其活化能高于PET,显示出相对较高的热稳定性。

Poly(ethylene terephthalate)-poly(tetramethylene glycol)(PET-PTMG)poly(ether-ester)s were synthesized by melt polycondensation.The thermal degradation reaction of PET-PTMG copolymers with differ-ent polyether contents in the presence of oxygen was investigated using thermogravimetric analysis.The re-sults showed that the introduction of polyether structures into copolymers resulted in poor thermal stability and sensi-tivity to oxygen.The degradation activation energy of PET and PET-PTMG copolymers in air was calculated using the Kissinger method.PET exhibited a two-step reaction,with an apparent activation energy(E.)of 179 kJ/mol for the first step and 148 kJ/mol for the second step.The copolymers with different polyether contents exhibited a three-step reaction,with E.values ranging from 66 to 97 kJ/mol for the first step,196 to 197 kJ/mol for the second step,and 135 to 142 kJ/mol for the third step.The application of the Flynn-Wall-Ozawa method re-vealed that the poly(ether-ester)s exhibited lower activation energy and poorer thermal stability at the initial stage of degradation.However,in the later stages of the reaction,their activation energy was higher than that of PET,demonstrating relatively better thermal stability.