分子量对PAMS热降解等温活化能的影响

聚α-甲基苯乙烯(PAMS)是制备激光惯性约束聚变(ICF)用靶丸的重要芯轴材料之一。采用快速热解气相色谱-质谱法(Py-GC-MS)和热重分析技术(TG/DTG)分析了不同分子量PAMS的热降解产物和热降解温度，并通过Arrhenius方程计算了不同分子量PAMS的等温热降解活化能。结果表明:分子量对PAMS热降解产物的影响可忽略不计，其热降解产物均为α甲基苯乙烯单体，且产率均接近100%；热降解温度随PAMS分子量的增加而降低，其热降解温度介于240~450 ℃之间；在相同降解率下，随分子量的减小，PAMS的热降解活化能增加，且PAMS的热降解活化能随着热降解率的增加而增加。

Effect of molecular weight on isothermal activation energy of PAMS thermal degradation

Poly-α-methylstyrene (PAMS) is one of the most important mandrel materials used in the fabrication of laser inertial confinement fusion (ICF) targets. The effects of the molecular weight on the degradation products and degradation temperature of PAMS were investigated using fast pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), thermogravimetric analysis (TG/DTG) and isothermal degradation activation energy of PAMS was calculated by Arrhenius equations. The Py-GC-MS results show that the pyrolysis of PAMS was found to yield α-methylstyrene monomer exclusively.Moreover, it also suggested that the effect of molecular weight on the degradation products of PAMS can be neglected. The TG results indicate that the thermal degradation temperature decreases as the molecular weight of PAMS increases, and the main thermal degradation temperature ranges from 240 to 450 ℃.Finally, with the decrease of molecular weight and the increase of thermal degradation rate, the activation energy of thermal degradation of PAMS increases.