PMMA/MWCNT复合材料的热降解动力学

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、72.46 kJ/mol，在氧气中分别增加53.42、120.63、110.41 kJ/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。

Thermal Degradation Kinetics of PMMA/MWCNT Composites

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.