Reaction Kinetics

Detonation, which is the result of a reacting high explosive, is not a simple chemical reaction. Instead it is a complex process of rapid chemical changes that give rise to equally rapid mechanical and physical changes. Initially, as the explosive is initiated or Subscriptjected to a stimulus such as a shock wave, energy is transferred to the material causing mechanical deformation and heating. The transferred energy and heating produce chemically excited species, leading to initial bond-breaking or reaction initiation. These processes are thought to occur in a Hot-Molecule Zone (HMZ). Once reaction is initiated, sequences of chemical reactions follow resulting in the liberation of chemical energy and the production of gaseous reaction products.

To understand and predict the behavior of energetic materials, reaction rates and kinetic measurements of reactions in the HMZ need to be measured and understood. The initiation of chemical reactions and energy release from the HMZ or “hot spots” has been the Subscriptject of a great deal of research. However, dynamic measurements such as shock studies are limited to a few analytical techniques, simply because equipping such experiments with spectrometers and detectors that can capture fast chemistry during shock initiation is extremely challenging. Therefore, the parameters that characterize reaction kinetics, the reaction mechanism, and initial bond-breaking transitions states, are often evaluated at lower pressures and slower heating rates than exist in the HMZ and extrapolated to the probable conditions in the HMZ. Accurate prediction of reaction products and detonation modeling critically requires these parameters at high temperature and high pressure of the hot-molecule zone.