Thermal decomposition of RDX/BAMO pseudo propellants

Measurements of gaseous species and temperature profiles for RDX/BAMO pseudo-propellants were performed to study their decomposition and the chemical and physical effects of their binder ingredient, 3,3'-bis- azidomethyl-oxetane (BAMO), on the base ingredient, 1,3,5-trimethylene trinitramine (RDX). The propellants were made from a physical mixture of RDX and BAMO in weight ratio of 80:20. Experiments were conducted at atmospheric pressure in argon with heat fluxes of 100 and 400 W/cm² delivered by a CO₂ laser. Gaseous samples were extracted through the use of quartz microprobes and analyzed by a triple quadrupole mass spectrometer (TQMS). Temperature profiles were measured using micro-thermocouple techniques to investigate surface and gas-phase reaction zones identified by the species measurement. Results of species and temperature measurements showed chemical and physical interactions between the two ingredients. From the species measurements, products of each ingredient, RDX and BAMO, were found to exist simultaneously throughout the gas phase; however, primary reaction chemistry in the gas phase was dominated by RDX. Three different categories of gaseous products were identified in the species measurements: species common to both BAMO and RDX; from RDX or BAMO only; and those which can not be attributed to RDX or BAMO alone. Surface temperatures were ~640 and ~670 K at 100 and 400 W/cm², respectively, while that of RDX was ~610 K for both heat fluxes. The temperature profiles showed the existence of an isothermal region in the gas phase, with the temperature of ~1200 K at 100 W/cm² and ~1500 K at 400 W/cm². The effect of BAMO in RDX/BAMO was clearly evident in the change of surface mole fractions and profiles of major species, expansion of reaction zones, and the constant temperature profile in the gas phase.