Preparation and Characterization of Desensitized ?-HNIW in Solvent-Antisolvent Recrystallizations

The solubility of hexanitrohexaazaisowurtzitane (HNIW) in solvent and solvent-antisolvent mixtures, and the temperature at which the HNIW's polymorph transforms were studied. The solubility of HNIW in solvent-antisolvent mixtures was measured at 30 C and these data were fitted to a generalized solubility curve. Recrystallization experiments were conducted at 30 C in the case of saturation with the volume ratio of ethyl acetate to petroleum ether (chloroform) ranging from 0:1 to 4:1. Desensitized HNIW was obtained by ethyl acetate and petroleum ether crystallization and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), High Performance Liquid Chromatography (HPLC) and Scanning Electron Microscopy (SEM). The FTIR and XRD spectra confirmed the structural features of ε-HNIW. The blocklike ε-HNIW grains had an average particle size of 160 ?m and high purity (98.52%). The decomposition of ε-HNIW was observed in the temperature range of 225-246 C by Differential Scanning Calorimetry (DSC). Furthermore, the impact and friction sensitivity tests suggested that the desensitized ε-HNIW was less sensitive than raw HNIW. Small scale gap tests with desensitized ε-HNIW showed that these crystals are less sensitive to shock initiation.