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 S ( T )max ), 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 S ( T )max , 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.