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 ( ) and maximum peak temperature ( ) from the non-isothermal DSC curves of HNIW/TNT cocrystal at different heating rates (), the following were calculated: the value of specific heat capacity ( ) and the standard molar enthalpy of formation , the apparent activation energy ( and ) and pre-exponential constant ( ) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method, density () and thermal conductivity (), the decomposition heat ( , 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 ( and ) of and corresponding to → 0, thermal explosion temperature ( and ), adiabatic time-to-explosion ( ), 50% drop height ( ) for impact sensitivity, critical temperature of hot-spot initiation ( ), thermal sensitivity probability density function [()] temperature () relation curves with radius of 1 m and ambient temperature of 300 K, the peak temperature corresponding to the maximum value of () relation curve ( ), safety degree (SD) and critical ambient temperature ( ) 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: = 464.45 K; = 477.55 K; = 472.82 K; = 485.89 K; = 4.40 s, 4.42 s, and 4.43 s for = 0, 1, and 2, respectively; = 531.90 K; = 19.46 cm; and the values of , , SD and 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.