聚苯醚绝缘材料热氧老化动力学参数计算方法

Calculation Method of Thermo-oxidative Aging Kinetic Parameters of Polyphenylene Oxide Insulating Materials

聚苯醚是新能源储能和5G通信等产业领域的重要材料。热重动力学参数计算是快速评定聚苯醚热寿命的关键。但热重分析常选用氮气气氛且升温速率较高,导致老化机理发生改变。为此,该文通过慢速升温和空气气氛下的热重实验模拟聚苯醚的实际老化过程。在多个升温速率对应失效温度区间内拟合温度积分数值解修正Doyle系数,对早期热氧降解阶段进行动力学分析、求取活化能,并推估该阶段反应机理函数以计算指前因子。结果表明,该方法求解活化能的精度较Flynn-Wall-Ozawa法和ASTM E1641-18法更高,且聚苯醚实际热氧老化可等效为遵循类幂律反应机理函数的单一反应,计算得到的指前因子比假定反应机理的标准方法更加可靠。上述工作为聚合物绝缘的热氧老化动力学参数计算提供了有效的技术方法。

Polyphenylene oxide(PPO)is an important material in industries such as new energy storage and 5G communication.The calculation of thermogravimetric kinetic parameters is the key to quickly evaluate the thermal life of PPO.However,the thermogravimetric analysis usually selects nitrogen atmosphere and high heating rates,which could cause the aging mechanism to change.Therefore,the actual aging process of PPO is simulated by thermogravimetric experiment under slow heating rates and air atmosphere.The Doyle coefficient is modified by fitting the numerical solutions of temperature integral in the interval of failure temperatures corresponding to multiple heating rates.Kinetic analysis is carried out in the early thermo-oxidative degradation stage to get the activation energy of PPO,and the reaction mechanism function during this stage is estimated to calculate the pre-exponential factor.The results show that the accuracy of this method is higher than that of Flynn-Wall-Ozawa method and ASTM E1641-18 method in solving the activation energy,and the actual thermo-oxidative aging of PPO can be equivalent to a single reaction following the quasi-power law reaction mechanism function,according to which,the calculation of the pre-exponential factor is more reliable than the standard method where the model of a chemical first-order reaction is preset.The above work provides an effective technical method for the calculation of thermo-oxidative aging kinetic parameters of polymer insulation.