Voids and density distributions in 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) prepared under various conditions

摘要

The density distributions of six samples of CL-20 were measured using the density gradient technique. This technique was used to determine which preparation procedure produced the highest average CL-20 density. Assuming crystals with fewer flaws result in reduced sensitivity to shock initiation,higher average crystal density (closest to the theoretical maximum density) would imply the least number of voids or inclusions. Based on hot-spot theory, better crystals, i.e., smaller number of flaws will reduce the shock sensitivity and perhaps other impact initiation mechanisms as well. Six samples from different synthesis and crystallization procedures gave average densities from 2.042 to 2.0230 g/cm~3 as density, the crystals were between 99.90 to 98.98% of the theoretical maximum density (TMD for epsilon-CL-20 is 2.044 g/cm~3). An attempt was made to account for the density difference by identifying voids in the crystals using polarized light microscopy. This method also gave some insight into the different morphologies produced by different crystallization techniques. In 3 cases voids on the order of several micrometers could be resolved in large CL-20 crystals.