Multi-scale Behaviors of GAP-Based Propellant during Thermal-Mechanical Coupling Aging

This study addresses the unclear thermo-mechanical aging mechanisms in novel glycidyl azide polymer (GAP)-based propellant by conducting thermal aging and thermo-mechanical coupled aging experiments, studying the impacts of thermo-mechanical interactions on the storage aging performance from the perspectives of macroscopic mechanical properties, mesoscopic morphology, and microscopic structures. The experimental results demonstrate that thermal aging mechanisms primarily involve binder matrix degradation and plasticizer decomposition. Since the pre-strain level does not exceed the debonding strain, no significant differences in storage performance are observed between thermal aging and thermo-strain coupled aging. However, the thermo-stress coupled aging significantly affects the mechanical properties. In addition to thermal aging mechanisms, creep effects induce permanent deformation and surface area expansion. Mesoscopic simulations are then conducted, demonstrating that an increased permanent deformation reduces interfacial strength, while a surface area expansion accelerates plasticizer volatilization, leading to the hardening of the binder matrix. The combined effect of these factors yields a significant decline in elongation at break.