Influence of the electric field on the low-temperature thermal decomposition of ammonium perchlorate/polystyrene propellant

Abstract

An electric field (100 V/cm at 230°C and 150°C) has been applied to ammonium perchlorate (AP)/polystyrene (PS) propellant mixtures in order to understand the low temperature decomposition behavior of the propellant. The charge-carrying species is anionic in nature at 230°C, which could be ClO₄-, but is cationic at 150°C, which could be either NH₄+ or H+. These results are parallel to that observed for pure ammonium perchlorate (AP) pellets [1]. The burning rate (r) of the propellant was found to follow the same trend as that for the thermal decomposition of the propellant on application of an electric field. At 150°C r was higher at the -ve electrode than at the +ve electrode, but at 230°C just the opposite was observed. Kinetic studies have confirmed that the decomposition of the orthorhombic AP follows two mechanism corresponding to E = 30 kcal mol^-1 (180–230°C) and E = 15 kcal mol^-1 (150–180°C).