The effect of aging and charge variability on the detonation performance of a conventional plastic-bonded high explosive

Plastic-bonded explosives (PBXs) are pressed composites of energetic crystals (>90 wt. %), polymeric binder, and an internal porosity structure (1–2 vol. %). The binder ensures material stability, while porosity promotes more reliable reaction initiation. These microstructural features critically influence the bulk mechanical and detonation performance properties of the high explosive (HE), yet the connection between microstructure and bulk behavior remains incompletely understood, complicating both manufacture and characterization. Aging of HE constituents under varying environmental conditions introduces additional uncertainty. For PBXs composed of cyclotetramethylene–tetranitramine (HMX), it is commonly assumed that detonation performance, specifically detonation velocity and energy release, are insensitive to microstructural details and do not vary significantly over time. This assumption simplifies constitutive modeling choices at the engineering scale. Here, we analyze four high-precision cylinder expansion tests of an HMX-based PBX varying in molding powder lot, pressing method, final pressed density, and pressing age. These data support hydrocode-based model calibrations of the explosive product equation of state, and these are used to quantify the effect of the described material variability on energy release characteristics. The results indicate that the detonation velocity increases with density and may also increase with age, though further experiments would be required for confirmation. No significant variation in energy delivery was observed across the tests.