Nonisothermal decomposition and safety parameters of HNIW/TNT cocrystal

To explore the thermal decomposition behavior and evaluate the thermal safety of the cocrystal 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW)/2,4,6-trinitrotoluene (TNT), its thermal and kinetic behaviors were studied by differential scanning calorimetry (DSC) technique. With the help of onset temperature (T _e) and maximum peak temperature (T _p) from the non-isothermal DSC curves of HNIW/TNT cocrystal at different heating rates (β), the following were calculated: the value of specific heat capacity (C _p) and the standard molar enthalpy of formation , the apparent activation energy (E _K and E _O) and pre-exponential constant (A _K) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method, density (ρ) and thermal conductivity (λ), the decomposition heat (Q _d, as half-explosion heat), Zhang-Hu-Xie-Li's formula, Smith's equation, Friedman's formula, Bruckman-Guillet's formula, Frank-Kamenetskii's formula and Wang-Du's formulas, the values (T _e0 and T _p0) of T _e and T _p corresponding to β → 0, thermal explosion temperature (T _be and T _bp), adiabatic time-to-explosion (t _tiad), 50% drop height (H ₅₀) for impact sensitivity, critical temperature of hot-spot initiation (T _cr), thermal sensitivity probability density function [S(T)] vs. temperature (T) relation curves with radius of 1 m and ambient temperature of 300 K, the peak temperature corresponding to the maximum value of S(T) vs. T relation curve (T ), safety degree (SD) and critical ambient temperature (T _acr) of thermal explosion. Results show that the kinetic equation describing the exothermic decomposition reaction of HNIW/TNT cocrystal is The following thermal safety parameters for the HNIW/TNT cocrystal are obtained: T _e0 = 464.45 K; T _p0 = 477.55 K; T _be = 472.82 K; T _bp = 485.89 K; t _tiad = 4.40 s, 4.42 s, and 4.43 s for n = 0, 1, and 2, respectively; T _cr = 531.90 K; H ₅₀ = 19.46 cm; and the values of T _acr, T , SD and P _TE are 469.69 K, 470.58 K, 78.57% and 21.43% for sphere; 465.70 K, 470.58 K, 78.17% and 21.83% for infinite cylinder; and 459.39 K, 464.26 K, 77.54% and 22.46% for infinite flat.