Facile preparation of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane/glycidylazide polymer energetic nanocomposites with enhanced thermolysis activity and low impact sensitivity

Abstract

1,3,5,7-tetranitro-1,3,5,7-tetrazocane/glycidylazide polymer (HMX/GAP) nanocomposites were successfully prepared via a facial sol–gel supercritical method. The as-synthesized HMX/GAP nanocomposites were characterized by X-ray diffraction (XRD), Raman, and Fourier-transform infrared spectroscopy (FT-IR), which indicated that HMX were successfully trapped in GAP gel skeleton. Scanning electron microscopy (SEM) images revealed that the GAP gel skeleton possessed nano-porous structure, which made it possible to load HMX particles. The thermal decomposition behaviours of GAP, raw HMX and HMX/GAP nanocomposites were determined by differential thermal analyser (DTA). The results indicated that GAP aerogel could promote the decomposition of HMX and enhance the interaction between GAP and HMX. The kinetic, thermodynamic and thermal stability parameters, such as activation energy (E_a), per-exponent factor (ln A), activation heat (ΔH^≠), activation free energy (ΔG^≠), activation entropy (ΔS^≠), critical temperature of thermal explosion (T_b) and the self-accelerating decomposition temperature (T_SADT) were calculated according to DTA analysis. The calculated results implied that HMX/GAP showed much lower activation energy than raw HMX. Similarly, the HMX/GAP presented a much lower T_b and T_SADT than raw HMX. According to the impact sensitivity tests, the mechanical sensitivities of HMX/GAP nanocomposites were significantly lower than those of raw HMX.