TG, EGA and kinetic study by non-isothermal decomposition of a polyaniline with different dispersion degree
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Polyaniline was obtained by oxidizing aniline in hydrochloric acid media with ammonium peroxidisulfate as oxidizing agent. Molar ratio aniline/oxidant was 1 and aniline/acid ratio: ½, at −5 and 400 °C, respectively, 800 mL water. The both compounds were studied using two different experimental strategies: the coupled TG-EGA (FTIR) technique by decomposition in dynamic air atmosphere and the kinetic analysis of TG data obtained at four heating rates (5, 7, 10 and 15 K min−1). The kinetic analysis of the TG non-isothermal data was performed with the Flynn–Wall–Ozawa, Friedman’s, and modified non-parametric kinetic (NPK) methods. By means of the coupled techniques spectroscopic arguments on the reaction mechanism were obtained, i.e. the oxidative degradation of the quinoine ring as the first step. The values of the activation energy by the three used methods are in good agreements. According to the NPK method, the termodegradation process consist in physical (diffusion) and chemical steps.
KeywordsCoupled TG-EGA Non-isothermal kinetics Polyaniline
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