Path to ε-HNIW with Reduced Impact Sensitivity, Cent

Abstract: New purification method was applied to obtain epsilon HNIW (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ε-HNIW) which has low impact sensitivity. The method is based on removing the impurities from a solution of alpha HNIW (α-HNIW) by a chemical reaction to obtain pure epsilon form. For comparison, selected different published methods for recrystallization of HNIW to obtain the epsilon form were studied. All the selected methods are based on solvent-antisolvent technique. The optimum parameters, such as type of solvent and anti-solvent, volume ratio of solvent to anti-solvent, rate of addition, speed of stirring, etc., were applied to enhance the crystal size and shape of ε-HNIW. Checking the polymorphs of the obtained HNIW was done by Fourier transform infrared spectroscopy (FTIR). The thermal stability of the prepared samples was studied by using differential thermal analysis technique (DTA). Qualitative analysis of the crystal size and shape was done using scanning electron microscope (SEM) devise. Quantitative measurement of the crystals sizes for the studied samples was determined by Laser scattering particle size distribution analyzer. Impact sensitivity was measured by falling hammer test. The results indicate that all the applied methods of recrystallization give ε-HNIW. The impact sensitivity of HNIW decreases by obtaining small particles with regular shape. All the used published methods produce ε-HNIW with higher impact sensitivity than other nitramines. While the obtained crystals from the new method has regular smooth surface, with small particle size and its impact sensitivity is lower than RDX and HMX