Natural Aging Versus Accelerated Aging of PBXs Containing TATB and HMX

ABSTRACT This investigation assessed aging effects on slow cook‐off safety of HMX and TATB‐based polymer‐bonded explosives through integrated experimental testing and numerical simulation. Three formulations were evaluated: PBX‐3 (HMX/TATB composite), PBX‐4 (TATB‐based), and PBX‐9 (HMX‐based) subjected to ambient storage spanning 10–11 years and accelerated aging at 55°C–75°C for 180–540 days. Experimental protocols adhered to STANAG 4382 standards, complemented by differential scanning calorimetry (DSC) analysis, density measurements, and finite element simulations. Results revealed pronounced formulation‐dependent degradation characteristics. PBX‐3 exhibited deteriorated thermal stability, with ignition temperatures declining from 220°C–240°C to 182.5°C and reaction times shortening from 66–83 to 52 min. Notably, accelerated aging occasionally yielded diminished reaction intensities (deflagration) compared to normal aging (explosion). PBX‐4 demonstrated exceptional stability, sustaining burning reactions after 11 years; however, accelerated aging (75°C, 180 days) induced deflagration with substantially reduced ignition temperatures (267°C–289°C to 203°C–215°C). PBX‐9 consistently detonated, establishing a stability hierarchy: PBX‐4 > PBX‐3 > PBX‐9. Numerical simulations successfully reproduced experimental trends through modified Arrhenius parameters, whereas mechanistic analysis identified critical degradation pathways encompassing polymer binder deterioration, decomposition‐induced void formation, and TATB's characteristic irreversible thermal expansion. These findings provide essential insights for munitions lifecycle management, demonstrating that even insensitive formulations may experience compromised safety following prolonged storage or elevated temperature exposure, thereby emphasizing requirements for systematic surveillance and optimized storage protocols.