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It is widely accepted that particle size distribution in granular beds of HE plays a large role in DDT events. Particle size analysis in the past has been performed with little or no detail. To better understand the effects of particle size distribution, extensive analysis has been done on the batch of course granular HMX (class A 920-32) used in these experiments and in other related experiments. This analysis helps to clarify the initial state of the particles, as well as extend the understanding of the effects of high density pressing on the particle size and morphology.


The goal of the particle size analysis was to measure the crystal size distribution of the HMX as accurately as possible. Basic analysis was done using a Coulter LS 230 particle size analyzer which uses light scattering by particles to measure size distributions. Samples were taken from solutions of about 0.1 g HMX in a bath of 10 ml of distilled water. Due to quick settling of the larger particles, special care was taken to obtain samples representative of the entire distribution by rapidly stirring the solution with a magnetic stir bar. Samples of approximately 1 ml were quickly transported from the solution to the particle analyzer using a dropper. Three basic experiments were run which study the effects of high-density pressing and ultrasonic treatment on HMX. The results of these experiments are listed below:
Effects of High Density Pressing
Effects of Extended Ultrasonic Treatment


A qualitative anaylsis of the granular HMX reveals widespread cracking of particles at densites as low as 70% TMD. As would be expected, the dammage becomes increasingly extensive at higher densities, however, the smaller particles produced by fragmentation seem to group together in larger agglomerates. An extensive collection of SEM's of granular HMX as various densities can be found at the following site: