Standard Enthalpy of Formation, Thermal Behavior, and Specific Heat Capacity of 2HNIW·HMX Co-crystals

Abstract

2HNIW·HMX co-crystals are crystals composed of HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazisowurtzitane) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), and the HNIW molecule and HMX molecule are combined with noncovalent bonds in a lattice at a 2:1 ratio. The 2HNIW·HMX co-crystals are successfully synthesized by Bolton’s method and characterized by powder X-ray diffraction, laser Raman spectrometer, differential scanning calorimeter (DSC), and high performance liquid chromatograph. The standard enthalpy of formation of 2HNIW·HMX co-crystals is obtained as 861.9 ± 18.6 kJ·mol–1 under the direction of a designed thermochemical cycle with a Calvet microcalorimeter. The thermal decomposition behavior of 2HNIW·HMX co-crystals was studied under the non-isothermal condition with DSC. The apparent activation energy (E) of the decomposition is 332.23 kJ·mol–1 by Kissinger method, 324.10 kJ·mol–1 by Ozawa method, 314.06 ± 4.26 kJ·mol–1 by Friedman–Reich–Levi method, and 306.81 ± 3.12 kJ·mol–1 by NL-INT-SY3 method, respectively. The pre-exponential factor (logA/s–1) is 29.33 ± 0.33 via compensation effect. A continuous C p mode of Micro-DSC III was used to determine the specific heat capacity (C p,m) of the target co-crystals from 283.15 to 333.15 K, and the C p,m is 1114.04 ± 10.92 J·mol–1·K–1 at 298.15 K. These results could provide valuable information on 2HNIW·HMX co-crystals for both theory and application.

Towards Computational Screening for New Energetic Molecules: Calculation of Heat of Formation and Determination of Bond Strengths by Local Mode Analysis

“…570–600 kJ mol −1 . We note that Zhang et al (2019) estimated a considerably higher value for ∆H f(s) of 861.9 ± 18.6 kJ mol −1 ; this was obtained indirectly using a calculated heat of reaction for the formation of solid CL-20/HMX from solid ε-CL-20 and β-HMX, that in turn used a thermochemical cycle based on measured enthalpies of dissolution of all species in acetonitrile, and literature ∆H f(s) values for ε-CL-20 and β-HMX.…”

Thermal Decomposition Kinetics and Compatibility of 3,5-difluoro-2,4,6-trinitroanisole (DFTNAN)

“…The critical temperature of thermal explosion ( ) is a vital parameter to evaluate the safety of the materials and ascertain the transformation from thermal decomposition to thermal explosion [ 25 ]. On the other hand, the self-accelerating decomposition temperature ( ) represents the maximum allowable ambient temperature for practical application.…”

Bioinspired Strategy for HMX@hBNNS Dual Shell Energetic Composites with Enhanced Desensitization and Improved Thermal Property

“…The contrary effects on thermal properties of shell materials show the PDA can be used as an effective inhibitor of phase transition and hBNNS can act as a stabilizer for thermal decomposition of energetic crystal. In order to further investigate the influence of shell additives on thermal decomposition of EM, the DSC experiments of different heating rates (5,10,15, and 20 K min −1 ) of raw HMX, HMX@PDA and HMX@PDA@BNNS-4 are conducted and the curves are presented in Figure 6b-f. Intuitively, the main exothermic peaks of EM tend to higher temperatures with the increasing of heating rates.…”

“…[ 9,10 ] Most powerful energetic materials are susceptible to external stimulations, and the investigation and storage of them may bring momentous disaster. Several strategies have been used to address this problem so far, such as designing and synthesizing new energetic compounds, [ 11–13 ] morphology optimization of EM, [ 14 ] co‐crystallization with low sensitivity energetic crystals, [ 15 ] and preparing polymer bonded explosive (PBX). [ 16–18 ] Among these approaches, PBXs consisting of 90–95 wt% of energetic crystals and 5–10 wt% of polymer binder or other components is facile and efficient, which can combine the merits of polymer materials without destroying the inherent structures of energetic crystals.…”