聚芳噁二唑纤维的热降解动力学

采用热失重分析法对聚芳噁二唑(POD)纤维在不同氛围下以不同升温速率升温时发生的热降解行为进行了动力学研究。主要采用Kissinger、Flynn-Wall-Ozawa及Coats-Redfern 3种方法研究得到POD纤维在氮气和空气氛围中的热降解动力学参数。结果表明:采用Flynn-Wall-Ozawa法得到的POD纤维在氮气氛围下的平均活化能为276 k J/mol;而采用Kissinger法得到POD纤维在热降解速率最大时的活化能为277 k J/mol。在空气氛围下,在第1阶段其热降解活化能为257.5 k J/mol,在第2阶段其热分解活化能从195.3 k J/mol逐步降低到79.1 k J/mol;最后,采用Coats-Redfern法并结合Flynn-Wall-Ozawa,得到了POD纤维热降解机制方程的积分形式,其机制均为随机成核和随后生长,仅反应级数有所差异。

Thermal degradation kinetics of poly (1,3,4-oxadiazole) fibers

In order to investigate the thermal degradation kinetics of poly(1,3,4-oxadiazole) (POD) fibers, thermal degradation performance of POD fibers at certain heating rates in different atmospheres of nitrogen gas and air  were analyzed thermogravimetry. Thermal degradation kinetic parameters of POD fibers were obtained according by Kissinger, Flynn-Wall-Ozawa and Coats-Redfern methods. The result show that the average activation energy of POD fibers in nitrogen gas atmosphere obtained by the Flynn-Wall-Ozawa method  is 276 kJ/mol, and the average active energy of POD fibers at the maximum thermal degradation rate obtained by Kissinger method is of 277 kJ/mol. And in air atmosphere, the thermal activation activation energy of POD fibers is 257.5 kJ/mol at the first stage, and gradually decreases from 195.3 kJ/mol to 79.1 kJ/mol at the second stage. By the combination of Flynn-Wall-Ozawa method and the Coats-Redfern method, the  integral form of the mechanism equation of thermal degradation of POD fibers is obtained, which is random nucleation followed by growth, and only the order of reaction is different.