聚亚苯基苯并二(口恶)唑的热分解行为

用热失重方法分析了聚亚苯基苯并二唑(PBO)纤维在不同气氛中的热分解行为,采用O zaw a法计算了PBO纤维在氮气和空气两种气氛中的热分解活化能。结果表明升温速率对PBO纤维的热分解温度有较大影响;氧气作为热分解反应的引发剂,大大降低了分解反应的活化能;由IR光谱对不同温度裂解产物结构的分析,推测了热氧化降解对PBO纤维分子结构的影响;在不同失重率时几乎相同的热分解活化能,表明无论热分解的气氛如何,PBO纤维的热分解均是一个无规引发的单阶段过程;结合PBO纤维在两种气氛中的热分解机理,解释了分解气氛对残碳率的影响。

Thermal Degradation of Poly(p-phenylenebenzobisoxazole)

TGA runs were performed for investigating thermal stability of(Poly(p-)phenylenebenzobisoxazole)(PBO) fiber.Under the air or nitrogen environment,the decomposition temperature was(affected) by the heating rate;a greater heating rate resulted in a higher decomposition temperature.Oxygen served the role of an initiator in thermal degradation of PBO fiber and significantly reduced its activation energy.Using the Ozawa method,the activation energy of thermal degradation in air was about half of that in nitrogen;therefore,PBO fiber was more heat resistant in nitrogen than in air.Almost the same(activation) energy was calculated from different residual weights suggesting the decomposition of PBO fiber in air or nitrogen was a single step process.IR analysis of the degradation reactions in air was employed for determining the effect of thermo-oxidation behavior on PBO fiber structure.