Dissolution of three insensitive munitions formulations

• Insensitive munitions constituents dissolve sequentially as predicted by solubility.
• Solubility of constituents differs by orders-of-magnitude producing porous particles.
• Good mass balances indicate IM do not photo-or bio-transformed in laboratory tests.
• The pH and color of the water samples can be used to estimate NTO concentrations.
• High solubility of constituents suggests that these will travel to groundwater.

The US military fires live munitions during training. To save soldiers lives both during training and war, the military is developing insensitive munitions (IM) that minimize unintentional detonations. Some of the compounds in the IM formulation are, however, very soluble in water, raising environmental concerns about their fate and transport. We measured the dissolution of three of these IM formulations, IMX101, IMX104 and PAX21 using laboratory drip tests and studied the accompanying changes in particle structure using micro computed tomography. Our laboratory drip tests mimic conditions on training ranges, where spatially isolated particles of explosives scattered by partial detonations are dissolved by rainfall.We found that the constituents of these IM formulations dissolve sequentially and in the order predicted by their aqueous solubility. The order of magnitude differences in solubility among their constituents produce water solutions whose compositions and concentrations vary with time. For IMX101 and IMX104, that contain 3-nitro-1,2,4-triazol-5-one (NTO), the solutions also vary in pH. The good mass balances measured for the drip tests indicate that the formulations are not being photo-or bio-transformed under laboratory conditions.

Micro computed tomography cross-section, optical image and dissolution data for an IMX104 particle. The graph shows dissolution data for three other IMX104 particles as well. Scale bar is 250 μm.Figure optionsDownload as PowerPoint slide