Density of RDX Crystals Grown During High Acceleration in an Ultracentrifuge

Abstract

AbstractRDX (cyclotrimethylene-trinitramine) crystals were grown during high acceleration (high g) in an ultracentrifuge. These crystals are found to have a density ∼0.6% greater than 1 g crystals and to have a greatly reduced defect content. The high g crystals should therefore have significantly reduced shock sensitivity as compared to commercial grade RDX. When a RDX saturated acetone solution is accelerated at 200,000 g, the RDX solute molecules move individually through the acetone solvent molecules to form a RDX crystal because the density of the RDX (Theoretical Maximum Density 1.806 g/cc) solute is more dense than the acetone (0.79 g/cc)solvent. Crystal growth is controlled by the g-force. Crystal defects including voids and solution inclusions caused by temperature variation or evaporation at 1 g are minimized and the RDX crystal density increases. A nitrogen pycnometer was used to measure the density of the RDX crystals grown at 1 g and at 200,000 g. The density of the RDX crystals grown at 200,000 g (1.7980±0.0003 g/cc) is found to be greater than the density of RDX crystals grown at 1 g (1.7881±0.0003 g/cc) by 0.0099 g/cc. The density of the high g crystal is 99.6% of the Theoretical Maximum Density of RDX.