PMMA/MWCNT复合材料的热降解动力学

Thermal Degradation Kinetics of PMMA/MWCNT Composites

采用溶液共混法制备了聚甲基丙烯酸甲酯/多壁碳纳米管(PMMA/MWCNT)复合材料,利用热重法研究了不同气氛下复合材料的热降解,并采用Flynn-Wall-Ozawa、Kissinger和Friedman等3种方法计算其动力学参数。结果表明,MWCNT的添加量为3%时,在氮气和氧气中复合材料的初始降解温度较纯PMMA分别提高了54.62℃和70.4℃,最大热失重速率温度也有一定程度的提高,说明MWCNT能显著提高PMMA的低温热稳定性,尤其是在有氧环境中,而对高温热稳定改善不明显;采用Kissinger法、Flynn-Wall-Ozawa法和Friedman法计算得到的活化能(Ea)变化趋势一致,当MWCNT的添加量为3%时,Ea较纯PMMA提高最多,在氮气中分别为45.99、95.10、72.46kJ/mol,在氧气中分别增加53.42、120.63、110.41kJ/mol;由Friedman法求解出复合材料的反应级数(n)在氮气中约为1.5,在氧气中约为0.9。

The composites based on poly(methyl methacrylate)(PMMA)and multi-walled carbon nanotubes(MWCNT)were prepared by a solution-blending method,and their thermal degradation processes under different atmosphere were investigated by a thermogravimetric method.The kinetic parameters of thermal degradation were obtained by the Flynn-Wall-Ozawas,Kissingers and Friedmans methods.The results indicated that the initial degradation temperature of composite containing 3 wt%increased by 54.62℃in nitrogen and 70.4℃in oxygen in comparison with pure PMMA,and its maximum heat loss rate was also improved to some extent.It was concluded that the introduction of MWCNT could effectively improve the low-temperature thermal stability of PMMA,especially in an aerobic environment.However,the improvement in high-temperature thermal stability was not so significant.The values of activation energy(Ea)calculated by Kissingers,flyn-wall-ozawas and Friedmans methods were in good agreement with each other.The composites achieved a maximum improvement in Ea when 3 wt%of MWCNT was added into PMMA.In addition,the order of reaction(n)deduced by the Friedmans method for the composites was approximately 1.5 in nitrogen and 0.9 in oxygen.