Gemini quaternary ammonium perchlorate salt as novel burning rate suppressant: Synergistic suppression mechanism on AP thermal decomposition in HTPB propellants

Burning rate suppressants are essential for regulating the burning rate of solid propellants. The regulation mechanism of Gemini quaternary ammonium perchlorate salt (GQAPS) on the combustion performance of ternary hydroxyl-terminated polybutadiene (HTPB) propellants was investigated. The propellant's. burning rate was reduced to 5.47 mm s⁻¹ at 7 MPa by adding 1 wt% GQAPS, indicating a superior burning rate inhibition efficiency of GQAPS. By constructing AP/GQAPS composites and analyzing their thermal decomposition properties, it was found adding 1 wt% GQAPS increased the activation energies of ammonium perchlorate (AP) during its low- and high-temperature decomposition stages by 11.86 kJ mol⁻¹ and 104.17 kJ mol⁻¹, respectively, and reduced the heat release during AP's high-temperature decomposition by 43.75 J g⁻¹. TG-FTIR analysis showed that the infrared absorption peaks associated with GQAPS decomposition products disappeared. Moreover, the maximum absorption intensity ratio of NO₂ to N₂O in AP/GQAPS composites decreased by 52.2 % compared to pure AP. These results demonstrated that GQAPS decomposition products competitively consumed reactive oxygen species generated during AP decomposition, thereby altering the oxidation pathway of NH₃ and synergistically inhibiting AP decomposition. However, excessive GQAPS diminished the inhibitory effect due to its inherent exothermic decomposition properties.