Competitive vaporization and decomposition of liquid RDX

The thermal decomposition of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Activation energies as a function of the extent of conversion, ?, have been determined by model-free isoconversional analysis of these data. In open pans, evaporation is a prevalent process with an activation energy of 100 kJ mol-1. Confining the system in either a pierced pan or a closed pan promotes liquid state decomposition of RDX that occurs with an activation energy of 200 kJ mol-1, which suggests scission of an N?N bond as the primary decomposition step. In such a confined environment, gas phase decomposition is a competing channel with an activation energy estimated to be 140 kJ mol-1. In a closed pan, RDX generates a heat release of 500 kJ mol-1 that is independent of both the heating rate, ?, and the mass.