Influence of Polymer in Shock-Induced Hotspot Formation and Reactivity due to Pore Collapse in High-Explosives Using Reactive Molecular Dynamics

The collapse of porosity in high-explosives (HEs) under shock loading has been extensively proven to be a dominant hotspot forming mechanism that can result in a detonation. Over the past decade, molecular dynamics (MD) simulations have been pivotal in revealing the atomistic-scale phenomena governing the shock-induced temperature rise and the transition to deflagration from pore collapse. However, such simulations do not include polymers, essential components in most composite energetic formulations. Consequently, the effect of polymer on the formation and reactivity of hotspots remains unclear. This is exacerbated as a significant fraction of porosity in polymer bonded explosives lie at the polymer-HE interfaces. Therefore, we conduct reactive MD simulations on the shock-induced collapse of a planar void with polymer-coated surfaces. The presence and arrangement of polymer on the void surfaces profoundly influence hotspot criticality and the rate of deflagration. Remarkably, certain configurations of inert polymer accelerate violent reactions within the collapsing HE material. Additional simulations with these configurations and increasing void sizes clarify the polymer’s expansion behavior and its effect on the resulting hotspot. These simulations provide both a mechanistic and chemical understanding of these phenomena.