Estimation of the kinetic parameters for thermal decomposition of HNIW and its adiabatic time-to-explosion by Kooij formula

Abstract

Abstract A differential/integral method to estimate the kinetic parameters (apparent activation energy Ea and pre-exponential factor A) for thermal decomposition reaction of energetic materials based on Kooij formula are applied to study the nonisothermal decomposition reaction kinetics of hexanitrohexaazaisowurtzitane (HNIW) by analyzing nonisothermal DSC curve data. The apparent activation energy (Ea) obtained by the integral isoconversional non-isothermal method based on Kooij formula is used to check the constancy and validity of apparent activation energy by the differential/integral method based on Kooij formula. The most probable mechanism function of thermal decomposition reaction of HNIW is determined by a logical choice method. The equations for calculating the critical temperatures of thermal explosion (Tb) and adiabatic time-to-explosion (tTIad) based on Kooij formula are used to calculate the values of Tb and tTIad to evaluate the thermal safety and heat-resistant ability of HNIW. All the original data needed for analyzing the kinetic parameters are from nonisothermal DSC curves. The results show that the kinetic model function in differential form and the values of Ea and A of decomposition reaction of HNIW are 3(1 − α)[−ln(1 − α)]2/3, 152.73 kJ mol−1 and 1011.97 s−1, respectively, and the values of self-accelerating decomposition temperature (TSADT), Tb and tTIad are 486.55 K, 493.11 K and 52.01 s, respectively.