Co-agglomerated crystals of 2,2′,4,4′,6,6′-hexanitro -stilbene/-azobenzene with attractive nitramines

Abstract

Co-agglomerated crystals (CACs) of trans-2,2,4,4′,6,6′-hexanitrostilbene (HNS) and trans-2,2′,4,4′,6,6′-hexanitroazobenzene (HNAB) with RDX, β-HMX, BCHMX and ε-CL-20 have been prepared. Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Raman studies and differential thermal analysis (DTA) have confirmed that this process leads to the formation of co-crystals (CCs), in which HMX is present in its δ-form, CL-20 in its β-form and trans-HNS changes its conformation to cis-form. In most cases, these significant structural changes and intermolecular-orientations have improved the impact sensitivities, mainly in some CACs with cis-HNS; for CL-20, on the other hand, the insertion of HNS or HNAB into its crystal lattice is destabilizing. Logical relationships between some FTIR, Raman vibrational modes of the CACs studied and parameters of their initiation and detonation have shown greater information about corresponding molecular structural relationships. The detonation energies of these co-crystals are in most of cases higher than that of correspond to the percentage of the coformers in them. It has been shown that this co-agglomeration can reduce the sensitivity of nitramines (with the exception of CL-20) roughly to the level of the sensitivity of analogous plastic-bonded explosives (PBXs), with the high-performance parameters of the resulting CACs being maintained. From a practical point of view, the combination of HMX and HNS appears to be the most optimal; these CACs at a molar ratio of 1.00/0.11 have exhibited the impact sensitivity of 47 J and the calculated detonation velocity 8.98 km.s−1.