Thermal degradation characteristics, kinetics and thermodynamics of micron-sized PMMA in oxygenous atmosphere using thermogravimetry and deconvolution method based on Gauss function

Abstract

Micron-sized poly (methyl methacrylate) (PMMA) with high flammability is widely applied in industries, constructions and transportations. Study on the thermal degradation behaviors of micron-sized PMMA in oxygenous atmosphere, which receives scarce attention to date, can provide valuable guidance for the prevention and mitigation of injuries and damages arising from the micron-sized PMMA dust explosions and fires. In the present study, the thermal degradation characteristics of micron-sized PMMA in air were investigated by thermogravimetry. Deconvolution method using Gauss function coupled with model-free and model-fitting methods was employed to conduct the kinetic modeling. The values of thermodynamic parameters (ΔH, ΔG and ΔS) were estimated. The results indicated that one peak and one shoulder occurred in the mass loss rate (MLR) variations of the micron-sized PMMA degradation in air. The values of MLR at peak and shoulder both decreased with heating rate. Besides, the average value of the MLR varied little with heating rate. The values of MLR at the peak and the average MLR of micron-sized PMMA degradation in air were both less than those of the traditional-sized PMMA degradation in air. The calculated kinetic parameters can be used to well predict the thermal degradation behaviors of micron-sized PMMA in air. Additionally, the micron-sized PMMA in air was easier to decompose than the traditional-sized PMMA in air. Non-spontaneous reactions were involved in the thermo-oxidative degradation of micron-sized PMMA. Besides, with the progressing of thermo-oxidative degradation, less energy was required and pyrolytic products with well-ordered structures may be generated.