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Resonant Acoustic Mixing and its applications to energetic materials

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Abstract

Resonant Acoustic Mixing (RAM) is a technology developed by ResoDyn Corporation which provides a low-energy contactless mixing system. This paper examines how the RAM technology can be applied to the processing of energetic materials and provides a comparison with conventional mixing techniques. Through research carried out to date, it has been established that RAM technology offers several advantages over traditional mixing techniques, especially where energetic materials are concerned. The main advantage lies in the relatively gentle mechanism of the RAM technique, where only minor damage occurs to sample particulates, with no blades or impellers being used in the process. The extent of particle damage encountered has been assessed by scanning electron microscopy, and shown that very little shear occurs during mixing at low accelerations. The process is also relatively thermally benign, although some temperature excursions have been encountered. Work has been undertaken to prepare energetic co-crystals and salts using a solvent-drop approach in the RAM, offering advantages in terms of diverse container compatibility and fast processing time.
... The co-crystal ( Figure 1a, space group P2 1 /c) was prepared using a ResoDyn LabRAM Resonant Acoustic Mixer (RAM, Figure 2) -a low-frequency (60 Hz) shaker/sonication technology [10] -following a method published by Nalas Engineering [11]. This method was chosen over the more well-known evaporative method for reasons of time and as a test of the RAM's known co-crystallisation capabilities [12]. ...
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Two energetic co-crystal systems have been investigated under pressure using neutron powder diffraction – 2(CL-20):HMX, and nitroguanidine:2-hydroxy-3,5-dinitropyridine (NQ:DNP). The 2(CL-20):HMX co-crystal was prepared with a ResoDyn LabRAM Resonant Acoustic Mixer using a published method. Neutron diffraction experiments were performed on the PEARL beamline at the ISIS Neutron Source in Harwell, Oxfordshire. Compression was observed in this system up to 3.5 GPa broadly in line with the results of DFT-D calculations, and equations of state were determined from the experimental data. No phase transitions were observed during the experiment. The NQ:DNP co-crystal was prepared by solvothermal co-crystallisation, and neutron diffraction experiments were also performed on the PEARL beamline. A potential phase transition was observed between 1.0 and 1.4 GPa. The crystal structure of this high- pressure phase is currently under investigation.
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Chapter
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