Non-isothermal decomposition kinetics of conductive polyaniline and its derivatives

Abstract The non-isothermal decomposition kinetics of conductive polyaniline (PANI) and its derivatives, poly(o-methoxyaniline) (POMA) and poly(o-ethoxyaniline) (POEA), was investigated by thermogravimetric analysis (TGA), under inert and oxidative atmospheres, using Flynn-Wall-Ozawa’s approach to assess the kinetic parameters of the decomposition process. The order of reaction was found to be dependent on the degree of conversion indicating that both the early and the later stages of polymer degradation were next the zero or pseudo zero order kinetics, whereas the intermediate stages follow a first order kinetics. The activation energy was found to be dependent on both the degree of conversion and PANI derivative. Activation energy values vary from 125 to 250 kJ/mol, to decompositions carried out under nitrogen, and 75 to 120 kJ/mol to oxidative atmosphere. Parent PANI presented the best thermal stability and suggesting that thermal stability is also influenced by derivatization and type of atmosphere used.

摘要 本研究采用热重分析（TGA），在惰性与氧化气氛条件下，针对导电聚苯胺（PANI）及其衍生物聚邻甲氧基苯胺（POMA）、聚邻乙氧基苯胺（POEA）的非等温分解动力学开展研究，借助弗林-沃尔-奥扎瓦（Flynn-Wall-Ozawa）法确定分解过程的动力学参数。结果表明，反应级数取决于转化率：聚合物降解的早期与后期阶段均近似遵循零级或准零级动力学规律，而中间阶段则符合一级动力学。活化能同时受转化率与聚苯胺衍生物种类的影响：在氮气气氛下开展的分解实验中，活化能取值范围为125~250 kJ/mol；在氧化气氛下则为75~120 kJ/mol。母体聚苯胺展现出最优的热稳定性，这表明热稳定性同时受侧链衍生化程度及所用气氛类型的影响。