Study on the isothermal decomposition of CL-20/HMX co-crystal by microcalorimetry

Abstract

The thermal decomposition behavior and kinetics of CL-20/HMX co-crystal were studied by microcalorimetry at the temperature interval of 448.15–468.15 K. The thermal stability of CL-20/HMX co-crystal is mediated by the individual thermal stabilities of pure CL-20 and HMX. CL-20 has a catalytic effect on HMX decomposition. The heat flow curve of CL-20/HMX co-crystal is not a single exothermic peak, and there is an obvious inflection point when the degree of decomposition α = 50 %. The mechanism function and kinetic parameters of CL-20/HMX co-crystal are obtained. Before the inflection point, the model conforms to the Avrami-Erofeev equation, and the activation energy is 166.80 kJ mol−1. After the inflection point, the model conforms to the Jander model, and the activation energy is 174.43 kJ mol−1. The thermal decomposition process of CL-20/HMX co-crystal is not a simple superposition process, but has coupling feature. The decomposition residues are analyzed and identified by high-performance liquid chromatography, Fourier-transform infrared spectroscopy, and scanning electron microscopy, and the isothermal decomposition of CL-20/HMX co-crystal is extensively discussed.