不同气氛下氟醚橡胶热分解动力学的对比研究

A comparative study of non-isothermal kinetics of fluoroether rubber under different atmosphere

摘要:

利用热失重分析方法（TGA），研究了氟醚橡胶生胶在空气和氮气中的热分解规律，并探讨了五种升温速率下的热分解动力学。应用Flynn-Wall-Ozawa法计算获得了其热解过程的动力学参数，并利用Popescu法推断得到了热解过程的反应机理函数。研究结果表明：氟醚橡胶生胶只呈现出一个主要的热失重峰；升温速率越大，热分解温度越高；氮气中更稳定且氧气对其热分解有一定的促进作用；空气中的热分解活化能平均值为172.5kJ/mol，氮气中的为260.9kJ/mol；两种气氛下，热解过程均不能由单一的机理函数来描述；空气中，340℃~370℃阶段机理符合相边界反应，球形对称，370℃~380℃阶段机理函数符合Ginstling-Brounshtein(G-B)方程，380℃~400℃阶段符合Zhuralev (Zh)方程；氮气中，400℃~430℃阶段机理函数符合Ginstling-Brounshtein(G-B)方程，430℃~460℃阶段机理符合相边界反应，球形对称。

Abstract:

The pyrolysis characteristics and kinetics of fluoroether rubber in air and nitrogen flow were studied by thermogravimetric analysis at five different heating rates. The kinetic parameters of the pyrolysis process were calculated using the method of Flynn-Wall-Ozawa and the mechanism of reaction were investigated using the method of Popescu. The results suggested that as the heating rates increasing, the pyrolysis temperature of the sample is moved to be higher. There is only one peak in DTG curves. The sample is more stable under nitrogen flow and the pyrolysis process of it is promoted by oxygen. It was found that the average value of the activity energy in air is 172.5kJ/mol, while 260.9kJ/mol in nitrogen. The pyrolysis process in air are well described by the model of Three dimension (R3) between 340°C and 370°C, by the model of Ginstling-Brounshtein (G-B) between 370°C and 380°C, and by the model of Zhuravlev (Zh) between 380°C and 400°C. While the thermal decomposition process in nitrogen are well described by the model of Ginstling-Brounshtein (G-B) between 400°C and 430°C, by the model of Three dimension (R3) between 430°C and 460°C.