Molecular model for cooperative propagation of shock-induced detonations in energetic solids and its application to nitromethane

Abstract

We present a simple molecular model for the propagation of shock-induced detonation waves in energetic solids. The explosive propagation of molecular dissociation is explained by energy transmission from one molecule to the next one. A numerical study shows that the model can explain the main experimental features of detonations in energetic compounds and particularly the fact that the detonation speed is characteristic of the material and not of the initial excitation, the existence of two unequal dissociation and detonation thresholds, and the possibility of ‘‘superdetonations’’ for large initial excitations. This model allows us to point out microscopic conditions that a solid must fulfill to sustain detonation waves. It demonstrates that the intramolecular potential plays a significant role in determining the characteristics of a detonation. The model predicts that a materials sensitivity to shocks and the velocity of the detonation wave are largely independent. It is then applied to solid nitromethane: The parameters that it involves are determined for this compound and we show that nitromethane meets the requirements to sustain detonation waves with a propagation speed which is in agreement with the experimental value estimated for this compound in solid phase.