Isothermal decomposition of CL- 20 before and after thermally induced ε-γ crystal transformation

Abstract

The ε-γ crystal transformation of CL-20 (hexanitrohexaazaisowurtzitane) was examined using a self-made constant temperature decomposition gas measuring device, and the isothermal decomposition kinetic parameters of ε-and γ-CL-20 with different crystal phases were obtained. Results show that the pressure temporal curves of CL-20 before and after crystal transformation have their own decomposition mechanism, indicating that the phase transformation has a significant effect on CL-20 decomposition. The kinetic parameters of ε- and γ-CL-20 were also calculated by Arrhenius and Mode matching methods. The activation energy (Ea) of ε-CL-20 decomposition was 118.82 kJ·mol−1 in the temperature range of 423–443 K, and the Ea of γ-CL-20 decomposition was 77.74 kJ·mol−1 in the temperature range of 453–468 K. The storage life of ε- and γ-CL-20 was estimated by Semenov equation. When the reactivity reaches 0.5 %, the storage time of ε-CL-20 at room temperature (298 K) is 227.8 years. Finally, the gas and solid residues obtained after CL-20 decomposition by SEM, FT-IR, and GC techniques. The possible decomposition mechanism of ε-CL-20 was proposed.