Study on the mechanism of TATB's effect on the thermal stability of HMX-based PBX

Thermal loads can induce damage and performance degradation in energetic materials. In this study, thermal shock experiments were conducted on HMX-based and HMX/TATB-based polymer-bonded explosives (PBXs), with the composition ratio optimized using Materials Studio. Scanning electron microscopy (SEM), industrial computed tomography (CT), thermal analysis, Brazilian splitting tests, and impact sensitivity tests were employed to systematically investigate structural evolution and performance degradation under thermal shock. The results show that TATB effectively mitigates crystal/binder interfacial damage and improves structural integrity. After thermal shock, the porosity of the HMX-based PBX increased by 4.45%, compared with 3.51% for the HMX/TATB-based PBX. The latter also exhibited improved apparent thermal stability, attributed mainly to partial binder melting, which fills intergranular gaps, restricts the escape of pyrolysis products, and promotes localized decomposition. The tensile strength of the HMX-based PBX decreased by 17.5%, whereas that of the HMX/TATB-based PBX decreased by only 5.8%. Fracture morphology further indicates that TATB reduces material stiffness while enhancing fracture toughness. Impact sensitivity decreased by 11.54% and 1.46% for the HMX-based and HMX/TATB-based PBXs, respectively, indicating that TATB suppresses sensitivity variation induced by thermal shock. Overall, TATB moderately sacrifices stiffness while significantly improving the toughness, thermal stability, and structural stability of PBXs, thereby mitigating performance degradation under thermal shock and providing a basis for designing high-reliability PBXs for complex thermal environments.