Non-Isothermal Decomposition Kinetics, Heat Capacity, and Thermal Safety of 2-Nitroimino-5-Nitro-Hexahydro-1,3,5-Triazine (NNHT)

摘要

The kinetic equation describing the thermal decomposition reaction of NNHT obtained by TG-DTG data, integral isoconver-sional non-linear method and integral method of treating TG-DTG curves is dα/dt = 10~(12.86)(1 -α)~(3/2)e- ~(-1.5849×10~4/T). The specific heat capacity (C_p) of NNHT was determined with the continuous C_p mode of the microcalorimeter. The equation of C_p (T) was obtained. The standard molar heat capacity of NNHT was 218.41 J mol~(-1)K~(-1) at 298.15 K. With the help of the onset temperature (T_e) and maximum peak temperature (T_p) from the non-isothermal DTG curves of NNHT at different heating rates (β), the apparent activation energy (E_k and E_O), and the pre-expo-nential constant (A_K) of the thermal decomposition reaction obtained by Kissinger's method and Ozawa's method, C_p obtained by microcalorimetry, density (p) and thermal conductivity (X), the decomposition heat (Q_d, taking half-explosion heat), Zhang-Hu-Xie-Li's formula, Smith's equation, Friedman's formula, Bruckman-Guillet'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_(Tlad)), 50 % drop height (H_(50)) of impact sensitivity, critical temperature of hot-spot initiation (T_(cr)), thermal sensitivity probability density function [S(T)] versus temperature (T) relation curves for spheroidic NNHT with radius of 1 m surrounded with ambient temperature of 300 K, peak temperature corresponding to the maximum value of S(T) versus T relation curve (T_(S(T)max)), safety degree (SD), and critical ambient temperature(T_(acr)) of thermal explosion of NNHT are calculated. The following results of evaluating the thermal safety of NNHT are obtained: T_(SADT)= T_(e0) = 453.34 K, T_(SADT)=T_(p0)=454.86 K, T_(be)=462.68 K, T_(bp)=467.22 K, t_(TIad) = 1.03 s, H_(50) = 17.69 cm, T_α = 461.4 K. SD = 72.74%, P_(TE) = 27.26 %, and T_(act) = 321.96 K.