Thermal Kinetics of Energetic CL-20/BTF Cocrystal Induced by Strong Intermolecular Coupling

Energetic cocrystals are an attractive new family ofexplosives with a potential for high energy and low sensitivity. Thepractical application of cocrystal explosives highly requires in-depthunderstanding of their thermal kinetic behavior, but the relevantresearch is still rare. In this study, we selected CL-20/BTF(2,4,6,8,10,12-hexanitrohexaazaisowurtzitane/benzotrifuroxan) coc-rystal as a typical cocrystal explosive to investigate its thermalkinetics and decomposition mechanism. The thermal behavior ofCL-20/BTF shows no phase transition or solid-liquid meltingprocess before decomposition, which is distinct from those of pureCL-20 and BTF crystals. Further, we identified the thermaldecomposition of CL-20/BTF as a particular reaction kineticsconsisting of two parallel autocatalytic paths, in which the contribution of these two paths to the overall reaction varies with thechange of heating rate. Based on the established kinetic model, important thermal safety indicators including TMRadand SADT aresimulated. Finally, in situ infrared spectroscopy was performed to detect the molecular evolution of CL-20/BTF cocrystal duringthermal decomposition, which is helpful to understand the origin of its thermal kinetics. It is found that the unique decompositionmechanism of strong intermolecular coupling between CL-20 and BTF molecules is responsible for the parallel reaction paths of thethermal kinetics of the CL-20/BTF cocrystal.

Automated summary

In this study, the thermal kinetics and decomposition mechanism of the CL-20/BTF cocrystal explosive were investigated. It was found that the cocrystal does not undergo phase transition or solid-liquid melting before decomposition, and its thermal decomposition consists of two parallel autocatalytic paths.