Anomalous sensitivity related to crystal characteristics of 2,6-diamino-3,5-dinitropyrazing-1-oxide (LLM-105)

Abstract

Sensitivity is one of the greatest concerns in explosive materials, and its underlying mechanism remains ambiguous. In this study, 2,6-diamino-3,5- dinitropyrazine -1-oxide (LLM-105) crystals with different morphologies, such as crosswise, needle, plate, block, diamond, and spherical shapes, were prepared using a solution crystallization method, and their crystal characteristics and sensitivity were investigated. It was found that the H50 values (impact sensitivity) of LLM-105 vary within an extremely wide range of 33.8–112.2 cm and are mainly influenced by the particle morphology, crystal integrity, particle surface defects, and roughness, but are mostly independent of intracrystalline defects and particle sizes. The friction sensitivities of all samples are zero and are unaffected by the crystal characteristics. The G50 values (shock sensitivity) are within the range of 0–6.9 mm, increasing with decreasing particle sizes and the apparent crystal density. Notably, LLM-105 crystals with a spherical shape, good integrity, smooth surface, and fewer defects are insensitive to impact and shock impulse. The relationships between the crystal characteristics and the sensitivity of LLM-105 are extremely complex and show some abnormal phenomena, which can be attributed to the crystal packing style and aggregated microstructures of LLM-105.