Study On Preparation And Properties Of Nanoscale Energetic Materials

In this paper, a novel reprecipitation method proposed by Nakanishi et al. for preparation of microcrystals of organic compounds was systematically studied in theory and experiment.The thermodynamics and dynamics of forming and growth of particles in this method were analyzed by theoretical method. A novel model that included particles formation based on ' LaMer model' and a subsequent particles growth through ' Ostwald ripening ' was established. The new model can explain Nakanishi's experiment for the growth of perylene microcrystals. Compared with the old model established by Nakanishi et al, the new model characterized in explaining all experiment results and clear meaning of apparent activation energy. The influences of reprecipitation conditions on the preparation of nanoparticles were analyzed on the basis of this model.The nanoparticles of RDX, HMX, NH₄NO₃, and NH₄ClO₃ have been prepared by reprecipitation method on the basis of theoretical research. In the experiment, influences of main experimental conditions, such as concentration of solution, ripening time, temperature, and properties of non-solvent on the preparation of nanoparticles have been studied.The research on the above substances expressed that concentration of solution directly effect the particles size, the higher concentration help to get the larger particles size, on the contrary less particles size will be obtained. At the same concentration of solution, the increase of solution will lead to larger size and anomalous particles. Preparation of particles was obviously influenced by experiment temperature, higher temperature (30℃) lead to larger particles size, strong aggregation and lower yield. Lower temperature is helpful to obtain less particles size, weaker aggregation and higher rate of production. The solubility of substance in non-solvent effect on the preparation, the lower solubility is helpful to obtain lower size, weak aggregation, spherical particles. The property of solvent is also one of the influence factors, higher solubility of the solvent is favorable to reduce average particles size, and well dispersibility of the particles. The influence of all above experiment factors on preparation of nanoparticles conform to the results predicted with the new model, thus experiment results verified our new modelThe many properties of HMX with particles size in 20～200nm were characterized. The XRD pattern showed that the HMX particles contain two phases (λ- and β-HMX).