燃气管用PE100级混配料的热分解动力学和机理

Thermal Decomposition Kinetics and Mechanisms of PE100 Compound for Gas Pipes

采用热重分析法测定了在氮气气氛中2、5、10、20℃/min 4种不同升温速率下的燃气用PE100级混配料热分解过程。采用Kissinger法、Flynn-Wall-Ozawa方法和Coats-Redfern法考察了燃气用PE100级混配料热分解动力学和机理。运用Toop法对PE100级混配料在不同温度下的寿命进行了评估。结果表明,PE100级混配料的热失重为一步分解反应;Kissinger法求得热分解平均活化能(E)为327.8 kJ/mol,Flynn-Wall-Ozawa法求得的E为304.6 kJ/mol,表观指前因子(lnA)值为53.9 min^-1;在12种常见热分解模型中,R2即圆柱对称的收缩机制最适合描述PE100级混配料热分解反应过程;50℃下,Kissinger法和Flynn-Wall-Ozawa法求得的PE100级混配料寿命分别为7.4×10^8年和7.9×10^7年,随着温度的升高,寿命急速降低。

Thermogravimetric analysis was used to determine the thermal decomposition process of PE100 compound for gas pipes at 2,5,10,20℃/min under four different heating rates in nitrogen.The thermal decomposition kinetics and mechanisms of PE100 compound were investigated by the Kissinger,Flynn-Wall-Ozawa and Coats-Redfern methods.The Toop method was used to evaluate the lifetime of PE100 compound at different temperatures.The results indicated that the thermal decomposition of PE100 compound presented a typical one-step reaction,and its average activation energy was 327.8 and 304.6 kJ/mol obtained from the Kissinger and Flynn-Wall-Ozawa methods,respectively.Moreover,the lnA value of apparent prefactor for PE100 compound was 53.9 min^-1.Among the 12 common thermal decomposition models,the cylindrical symmetric contraction(R2)was considered as the most suitable mechanism to describe the thermal decomposition process of PE100 compound.The lifetime of PE100 compound obtained by Kissinger and Flynn-Wall-Ozawa method at 50℃ was 7.4×10^8 and 7.9×10^7years,respectively.However,the lifetime decreased rapidly with a rise of temperature.