Thermal decomposition kinetics of PBAN-binder and composite solid rocket propellants

Abstract

Thermogravimetric analysis at heating rates between 0.5 and 10°C min−1 has been used to study the decomposition kinetics of the PBAN binder and three propellants based on ammonium perchlorate (AP) with PBAN, HTPB, or BAMO-AMMO binders. Thermal runaway was observed for the PBAN and HTPB propellants at heating rates faster than 4.5 and 3°C min−1, respectively. The multistep decomposition kinetics were analyzed by an advanced isoconversional method that showed that the effective activation varies with the extent of decomposition of the studied systems. For PBAN the activation energy increases from 100 to 200 kJ mol−1 throughout the polymer decomposition. In propellants the major mass loss step primarily relates to AP decomposition accompanied by some degradation of the polymer binder. For the PBAN and HTPB propellants this step shows respective increases in the activation energy from 60 to 180 kJ mol−1 and from 100 to 230 kJ mol−1. The major decomposition step of the BAMO-AMMO propellant has a fairly constant activation energy of 120 kJ mol−1.