Solubility and Evaporative Crystallization Study of HMX in Methyl-Ethyl-Ketone and Quantitative Determination of Its Polymorph in Samples Using XRD and Raman Spectroscopy

In this research, with evaluation of the solubility of cyclotetramethylene tetranitramine (HMX) explosive in different concentrations of water- methyl ethyl ketone (MEK) solvent, at a temperature range of 40-70 °C, the solubility and some thermodynamic parameters such as enthalpy of dissolution and mixing were calculated. Thereafter, in order to increase the capacity of the crystallization process, the effect of digestion of HMX in evaporative crystallization procedure on the morphology and polymorph conversion of crude HMX was investigated using electron microscopy, X-ray diffraction (XRD) and Raman spectroscopy. Then, two quantitative methods based on the XRD and Raman spectroscopy were developed for the determination of -HMX in  -type samples. The results showed that with the mentioned methods, -polymorph can be determined in the linear dynamic range of 0.32-5.25 wt. % in  -HMX. Also, the crystallization studies in MEK using digestion and evaporative crystallization showed complete conversion of crude HMX polymorphs to  -type, along with significant increasing in the crystallization capacity.