Thermal Kinetics of Polybenzoxazole Membranes Prepared from Hydroxyl containing Polyimide by Thermal Rearrangement

Abstract

Thermally rearranged polybenzoxazole (TR-PBO) with microcavities is a promising material for gas separation encompassing the polymeric upperbound. Since optimization of thermal treatment condition is crucial to obtain excellent performance, exploration of kinetics parameters through thermogravimetric analysis (TGA) provides thorough understanding on thermal conversion mechanism of this new class of materials. To understand polymer conversion kinetics of a novel TR-PBO where chain rearrangement occurred by releasing two moles of carbon dioxide at 350 to 450oC, we modified and applied Ozawa method which is widely use to study thermal decomposition kinetics. The reaction order of thermal rearrangement mechanism was determined and appropriate thermal treatment conditions were estimated. The different morphology of poly(hydroxy-imide) structures results in slight differences in maximum activation energy which was known as the conversion point here according to polymer chain rigidity. Base on the weight loss percentage at the conversion point in TGA curves, time required for full conversion to occur at a certain temperature could be calculated in this study.