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arXiv · 2610.28812

Polymer-Mediated Hotspot Evolution in Shock-Induced Pore Collapse in 1,3,5,7-Tetranitro-1,3,5,7-tetrazocane (HMX)-based Explosives

Jalen Macatangay·Brenden W. Hamilton·Alejandro Strachan
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Abstract

The initiation of detonation in high explosives (HEs) under shock loading is strongly influenced by the collapse of porosity and the subsequent formation of hotspots. As these materials are widely integrated with polymer binders to form polymer-bonded explosives, the collapse of pores at explosive-binder interfaces has received significant interest. Recent molecular dynamics (MD) simulations revealed that the shock-driven expansion of soft polymers (e.g. polystyrene) into a void produces greater pressure-volume (PV) work during recompression and higher local temperatures compared to pore collapse in neat HEs, ultimately expediting the onset of chemical reactions. Yet how pore collapse, interfacial phenomena, and binder chemistry jointly affect initiation remains insufficiently understood. We provide deeper insights into the role of polymer in hotspot evolution through reactive MD simulations, specifically characterizing its chemical behavior during the shock-induced collapse of voids at sizes approaching experimentally relevant length scales. We consider the HE 1,3,5,7-Tetranitro-1,3,5,7-tetrazocane (HMX) in a crystal-gap-crystal stack with polystyrene along the upstream surface. In the hydrodynamic collapse regime, hotspots nucleate at the material interfaces, with void length-dependence in PV work, shock temperature, and the onset of self-sustaining chemistry. Driven by shock-induced deformation and HMX decomposition, the binder undergoes backbone chain scission followed by extensive aromatic-backbone cross-bonding, akin to a graphite to diamond transformation. These reactions act as heat sinks, suppressing deflagration and ultimately inhibiting hotspot growth and coalescence between crystals. The simulations further link the polymer's chemical response to the shock-to-detonation transition in polymer-bonded explosives.

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Jalen Macatangay, Brenden W. Hamilton, Alejandro Strachan. 2026-10-20. Polymer-Mediated Hotspot Evolution in Shock-Induced Pore Collapse in 1,3,5,7-Tetranitro-1,3,5,7-tetrazocane (HMX)-based Explosives. https://arxiv.org/abs/2610.28812

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