Macrokinetics of decomposition of loose packed RDX in shock and detonation waves

The boundary retardation method was used to study the decomposition of loose packed density RDX behind the front of shock waves with amplitudes ranges from values critical for reaction initiation to those typical of detonation. The threshold pressure P* and temperature T* at which the transition from a relatively slow decomposition in hotspots to fast bulk conversion occurs. It was demonstrated that this transition is associated with a change in the macrokinetics of the conversion of HE material behind the shock front. At pressures below P*, an analogy with the kinetic regularities of the thermal decomposition of RDX at normal pressure is observed. At P > P*, the conversion occurs in the regime of an adiabatic thermal explosion at a very high rate and has no analogues in chemical kinetics. The normal detonation regime is realized at P > P*. It was shown that the macrokinetic characteristics of normal detonation cannot be described within the framework of traditional approaches, with the help of the Arrhenius law or the concept of deflagration propagating from hotspots.