Analysis of thermal stability for slow burning propellant based on isothermal testing: Self‐accelerating decomposition temperature (SADT) calculation and validation

Burning rate suppressants (BRSs) refer to a series of additives that reduce the burning rate of propellants, crucial for achieving sustained and stable thrust. This research focuses on assessing the impact of ammonium sulfate and ammonium oxalate on thermal stability and their potential as BRSs. Due to the stronger inhibitory effect of ammonium sulfate on the AP proton transfer process, the activation energy of propellant's first decomposition can be increased from 94.71 kJ mol−1 to 129.69 kJ mol−1 at a 3 % addition level. Based on Semenov model, the self‐accelerated decomposition temperatures (TSADT) were calculated and validated through 7‐day isothermal test. Introducing ammonium sulfate and ammonium oxalate raised the TSADT from 197.31 °C to 220.90 °C and 215.06 °C, respectively, deviating less than 4 % from experimental results. Among the propellants tested, those with ammonium sulfate showed prolonged response delay times (44.43–33.60 h), lower superheating temperatures (222.8–445.5 °C), and reduced mass loss rates (33.0–71.4 %) after 7 days of isothermal storage at 220–240 °C. The consistency between thermal analysis and isothermal test underscores the significant impact of activation energy on thermal stability.