Microstructural Investigation of PBX 9501: Comparing Wet Slurry and Resonant Acoustic Mixing Techniques

The microstructure of a high explosive (HE) material directly influences the reactive behavior under a variety of insults. Furthermore, the preparation method of polymer-bonded explosives (PBX), as well as the constituent material particle size distribution and consolidation parameters, will dominant the microstructural features that are observed. Here, we compare batches of PBX 9501 prepared by the typical wet slurry process and resonant acoustic mixing. The prills produced by the wet slurry process will lead to an inherently different microstructure than the coated powder produced by resonant acoustic mixing. We observed that the conditions required to consolidate (press) the material to the nominal PBX 9501 density of 1.835 g/cc varied depending on the prill size and preparation technique. SEM imaging, X-ray microcomputed tomography, and ultra small-angle x-ray scattering analysis reveal distinct differences in the void structure and void size distribution.