To investigate the thermal decomposition behavior of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetra- zocine (HMX), the T-Jump/FTIR spectroscopy was used to determine the main gaseous products released from the thermolysis of HMX in real time. HMX was flash-pyrolyzed at a heating rate of 1000 ℃•s^－1 to set temperatures under Ar atmosphere of 0.1, 0.2, 0.3 and 0.4 MPa. With the help of rapid scanning fourier transform infrared (FTIR) spectroscopy to analysis the species and concentration of gaseous products of HMX, the effects of temperature and pressure on the initial products were studied. The results show that 10 specific IR-active gas products (CO, CO₂, NO, NO₂, N₂O, HCONH₂, CH₂O, H₂O, HNCO and HCN) for 5 s occur during the fast thermolysis process. The curves of concentration of the main gaseous products vs time were obtained. On the basis of N₂O/HCN ratios, the effects of temperature and pressure on the thermolysis processes and on the decomposition mechanism of HMX were proposed. It is considered that C—N bond rupture in two competing branches for HMX decomposition is favored at lower temperature. The secondary reactions between the gaseous products are proved by the change of pressure.

Key words: flash pyrolysis, T-Jump/FTIR, HMX, pressure