Co-agglomerated crystals of cyclic nitramines with the nitrogen rich 3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-1,2,4,5-tetrazine (BTATz)

Abstract

Coagglomerated crystals (CACs) of the cyclic nitramines RDX, β-HMX, BCHMX and ε-CL20 with 3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-1,2,4,5-tetrazine (BTATZ) were prepared using the “coagglomeration method” (classified as slurry cocrystallization) in two parallel batches, one with a linear stirrer (B1) and another with a cross stirrer (B2). The batch B2 procedure is more suitable because the CACs show a better crystal morphology, higher density, and quality of the crystal surface. These CACs, characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman studies, and differential thermal analysis, convincingly contain cocrystals, in which HMX is stabilized in its α form and CL20 in its β form. On the basis of the results obtained, new relationships were found between the N–N bond stretching and FTIR C–H bond stretching vibrations in CACs, on the one hand, and their impact sensitivity, crystal density, voluminous detonation energy (Q.ρ), heat of combustion and enthalpy of formation, on the other. These evidence that, together with the relation between ring deformation vibrations and the Q.ρ values, correspond to the idea of the method of initiation of energetic materials by impact and shock. The α-HMX/BTATz, prepared by method B2, was surprisingly the least sensitive (46 J) of the CACs studied and had a slightly better detonation energy than that of pure β-HMX (6097 versus to 5864 J·g−1).