膨胀聚苯乙烯热分解动力学分析和寿命预测

针对既有聚苯乙烯泡沫类外墙外保温系统的防火问题,在空气和氮气气氛下对非阻燃和阻燃型膨胀聚苯乙烯泡沫进行了热重分析。样品由10℃/min、20℃/min、40℃/min和50℃/min四个升温速率从室温加热至800℃。热分解动力学参数由Flynn-Wall-Ozawa(FWO)等转化率方法和多参数非线性回归方法(multivariate non-linear re-gression method)计算,结果表明六溴环十二烷(HBCD)阻燃剂可一定程度上提高EPS的热稳定性。EPS在空气和氮气气氛下热解可认为是单步反应。非阻燃聚苯乙烯泡沫在空气和氮气气氛下的热解过程可由自催化n阶反应机理描述。阻燃EPS在空气气氛下的热解机理为自催化n阶反应,在氮气气氛下则为n阶反应机理。基于动力学参数和反应机理,对聚苯乙烯泡沫在不同温度下的寿命进行了预测。

Thermal decomposition kinetics and lifetime prediction of expanded polystyrene foam

Concerning the fire protection problems of existing polystyrene foam exterior wall insulation systems, the thermo- gravimetric studies on the commercial grade non-retardant and retardant expanded polystyrene foam （EPS） were carried ）ut un- der air and nitrogen atmosphere from ambient temperature to 800℃ at heating rates of 10℃/min, 20℃/min, 40℃/min and 50℃/min. The dependence of the activation energy on the conversion degree was evaluated by using the isoconversional meth- ods （FWO method）. The multivariate non-linear regression method was applied for investigation of the kinetic model and the corresponding kinetic parameters. The obtained kinetics parameters reveal that the hexahromocyclododecane （HBCD） flame re- tardant can enhance the thermal stability of EPS. It can be conclude that the decomposition processes of EPS undergo a single step reaction in both air and nitrogen atmosphere. The decomposition of non-retardant EPS under air and nitrogen atmosphere can be described by nth-order reaction with autoeatalysis （Cn） kinetic model. For the retardant EPS, the decomposition process can be accurately describe by the Cn and Fn （nth-order reaction） kinetic model under air and nitrogen atmosphere, respectively. Based on the kinetics parameters and the kinetic models, the lifetime of EPS at different temperatures was predicted.