Detonation Performance of CL-20 and MDNT Co-crystal Versus Physical Mixture

A co-crystal of multiple explosive molecules can be pursued to potentially gain improvements over individual molecular crystalline materials. This process has sometimes been shown to produce energetic materials with desirable properties, such as detonation velocity, between that of the individual coformers. Since the initial synthesis of co-crystals can be limited, small scale experiments are needed to screen materials. Co-crystals can have unique material properties and crystal structure, whereas a physical mixture is simply a well-mixed combination of the known materials at the same molar ratio.  This study uses photon Doppler velocimetry (PDV) to compare the particle velocity and detonation pressure for hexanitrohexaazaiso-wurtzitane (CL-20) and 1-methyl-3,5-dinitro-1,2,4-triazole (MDNT) at a 1:1 molar ratio for both a co-crystal and a physical mixture of the two energetic materials using a very small amount of material (1.25 grams). This co-crystal has been predicted to detonate faster and at a higher pressure compared to the physical mixture based on measured enthalpies of formation, which is likely due to the bonding energy contained in the unique crystal structure of the co-crystal. It has also been shown to detonate at different speeds at the same density (1.4 g/cc) using microwave interferometry. The output particle speed and pressure should also be different between the co-crystal and physical mixture. The objective of this study is to determine if that difference can be resolved.