Influence of hard segment structures on the thermal decomposition and safety of PBT-ETPE/ammonium perchlorate (AP) thermoplastic composites

The thermal decomposition process of propellants is influenced by multiple factors, including binder structure, solid fillers type, and the interface properties between binders and solid fillers. Proper thermal decomposition behavior and thermal safety performance are crucial for the production, application and storage of propellants. The impact of binder structure on the thermal behavior of common propellant constituents is paramount for the application of binders. In this study, contact angle tests, SEM, TG and DSC were employed to investigate the influence of the structures of poly(3,3-bis(azidomethyl) oxetane-tetrahydrofuran)-energetic thermoplastic elastomers (PBT-ETPE) on the thermal decomposition process of PBT-ETPE/ammonium perchlorate (AP) composites. Multiple kinetics models and the Semenov model were utilized to analyze the impact of PBT-ETPE structure on the thermal decomposition kinetic parameters and thermal safety performance of the composites. Results indicate that the hard segment structure of PBT-ETPE exerts a direct influence on the thermal decomposition process of PBT-ETPE/AP. Binders with ordered hard domain structures demonstrate better thermal stability and higher activation energy, with a self-accelerating decomposition temperature (T_SADT) of 193.48℃. Binders with large but disordered hard domains exhibit enhanced interfacial performance with AP, enabling complete decomposition and high heat release, though activation energy and thermal safety properties are reduced (T_SADT: 176.43℃). These findings indicate that controlling the thermal properties of propellants by regulating the hard segment structures of binders is a straightforward and viable approach, facilitating their further application in military fields.