Supercritical Antisolvent Micronization of Cyclotrimethylenetrinitramin: Influence of the Organic Solvent

A supercritical antisolvent (SAS) process was used to prepare micronized cyclotrimethylenetrinitramin (RDX). This study examined the influence of different solvents at a fixed temperature (50 degrees C) and pressure (13.7 or 15 MPa) on the morphology, particle size (PS), and particle size distribution (PSD) using a semicontinuous SAS process, Dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone (AC), acetonitrile (ACN), n-methyl 2-pyrrolidone (NMP), and cyclohexanone (CHN) were used as solvents. The recrystallized RDX particles were characterized by scanning electron microscopy (SEM), particle size analyzer (PSA), Fourier transform infrared (FT-IR) spectroscopy, and differential scanning calorimetry (DSC). Depending on the solvent used, the recrystallized RDX particles showed a variety of morphologies, particle sizes, and particle size distributions (PSD). The mean particle size of the recrystallized RDX ranged from 2.6 to 17.7 mu m. The enthalpy change (Delta H = 583.4, 847.7, 967.1, 823.9, 1131, and 1620 J/g) for the exothermic decomposition of recrystallized RDX was much higher than that of the unprocessed RDX (Delta H = 381.5 J/g).