2,5-Dipicryl-1,3,4-oxadiazole (DPO) is a thermally stable, high impulse shock sensitive explosive, which decomposes in the solid state at a rate easily followed by isothermal differential scanning calorimetry between 575 K (302°C) and 598 K (325°C). The α-t plots follow a typical sigmoidal profile and the kinetic data has been analysed in terms of the two standard rate laws which characterise many sigmoidal nucleation, growth and decomposition reactions, viz. the Prout-Tompkins rate law and the Avrami-Erofe'ev rate law. Both give an excellent description of the reaction kinetics over the approximate range 0.08 < α <0.80, but the apparent reaction order associated with Avrami-Erofe'ev kinetics is temperature dependent. An Arrhenius plot based on Prout-Tompkins kinetics suggests that the thermal decomposition of DPO proceeds with an activation energy of 218 kJ mol−1 and a pre-exponential, In A(s−1), of 39.83, while that based on Avrami-Erofe'ev kinetic data yields an activation energy of 184 kJ mol−1 and In A(s−1) of 30.92. Ramifications of these results are discussed.
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Whelan et al. (1994) studied this question.