Energetic Materials-Models, Micro-measurements and Results

The development and evaluation of new classes of energetic materials requires new metrology methods able to test small samples of theses materials. The same problem appears when it is necessary to check time life of explosives and propellants from existing warheads. They are usually formed by crystals, surrounded by binder, and their detonation properties are very dependent of the type of nitration, of the used solvents for their crystallization and its granulometric size. Theoretic phenomenological models, more and more, take in account the transmission of shock wave between crystal and binder, the delay of its initiation, the cavitation phenomena between crystal and binder and the hot spot formation. However, it is very important to optimise these theoretical models with experimental results. In the presented particular case study, detonation PBX micro-samples, based in HMX with an inert (HTPB, epoxy) or energetic (GAP) binder, was performed on the meso-scale level, using the multifiber optical probes of 50 μm of maximum resolution, connected directly to a fast electronic streak camera with 0.6 ns resolution. The direct 2D observation of detonation progression and the particle to particle successive transition, of transmitted shock wave, through the binder, allows to analyse and to discuss, not only the cooperative formation of a multihead detonation front (DF), in the collection of particles surrounded by binder, but also the synenergetic effect, behind the DF, by the appearing of dissipative structures drawing spatial and temporal DF oscillations.