Abstract：In-situ FTIR spectroscopy is a rising and dynamic technique. This technique combines the advantages of investigation in-situ and accurate structure analysis by FTIR spectroscopy, and can detect real time chemical change in materials at different temperatures and obtain the relationship between micromechanism of materials and temperature. In the present paper, thermal decomposition of octahydro-1，3，5，7-tetranitro-1,3,5,7-tetrazocine (HMX) heated with a rate of 5, 10, 20 and 40 ℃·min-1, respectively, was investigated by in-situ diffuse reflection FTIR spectroscopy. The results demonstrate that intramolecular cyclization occurs in breakage of HMX with a heating rate of 5℃·min-1, while intermolecular cyclization appears with a heating rate of 10, 20 and 40 ℃·min-1. With increasing temperature, the rupture rate of C—N bond is faster than that of N—N bond, which verifies that the cleavage of C—N bond is the dominant rupture form. With increasing heating rate, the decomposition beginning temperature of C—N bond increases. Eight kinds of gaseous products such as CO2, N2O, CO, NO, HCHO, HONO, NO2 and HCN were determined. The decomposition mechanism of HMX was not affected with changing heating rate.
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