Examining explosives handling sensitivity of trinitrotoluene (TNT) with different particle sizes

It is critical to understand and mitigate for explosive sensitivity, from applications related to stockpile maintenance and development, to law enforcement safety, to basic research. The handling sensitivity of explosives is controlled by factors that span from fundamental intramolecular effects to mesoscale structure and defects. Although the drop-weight impact test has been used to characterize energetic material sensitivity for over 50 years, there is still very limited understanding on which features of explosives influence or control impact sensitivity. Fundamental chemistry is likely the most important player in handling sensitivity of energetics, however secondary effects such as particle size and morphology are thought to influence the results in impact sensitivity tests. We have recently discovered that batches of trinitrotoluene (TNT) obtained with a freshly synthesized method versus a historical lot sample exhibit significantly different impact sensitivity values. To determine if differences in particle size were the reason for the different results, in the present work we have prepared 13 different samples of TNT and tested each for particle size and impact sensitivity. Though the particle sizes of the samples range from 44 – 1502 µm, impact test values fall mostly within error, given the large standard deviation in the test. The historical lot TNT sample is an exception, and is more sensitive than the newly prepared batches. Overall, more work is needed to determine if other factors such as purity and particle morphology (rather than size) are more important for influencing impact test results in TNT.