Fude Nie

Green primary explosives have gained wide attention for environmental protection. A potential novel lead-free primary explosive, Al/Fe₂O₃/RDX hybrid nanocomposite was prepared by ultrasonic mixing, and its safety properties are discussed in detail. Results showed that their sensitivity and safety properties were a function of the specific surface area and proportions of their ingredients. Their impact sensitivity fell and their static discharge, flame, and hot bridge wire sensitivities rose as the specific surface area of nano-Fe₂O₃ increased. As the amount of Al/Fe₂O₃ nanothermite was increased, its impact sensitivity fell and its flame sensitivity rose; their static discharge and hot bridge wire sensitivities, however, followed an inverted “U” type change trend and were determined by both the particle size of the ingredients and the resistance of the nanocomposite. Their firing properties in an electric detonator depended on the proportion of the constituents. Thus, green nanoscale primary explosives are appropriate for a range of initiatory applications and can be created by adjusting their specific surface area and the amount of their constituents.

Purpose: The purpose of this study was to develop a novel and continuous method for preparing a nanosized particle of drug crystals and to characterize its properties. Materials and methods: A new apparatus was introduced to crystallize nanosized drug crystals of amitriptyline hydrochloride as a model drug. The samples were prepared in the pure state by ultrasonic spray, and elaborated deposition was completed via electrostatic adsorption. Scanning electron microscopy, X-ray powder diffraction, and atomic force microscopy were used to characterize the size of the particles; this was subsequently followed by differential scanning calorimetry. Results and discussion: Nanoparticles of drug crystals were successfully prepared. The size of the drug crystals ranged from 20 nm to 400 nm; the particle size of amitriptyline hydrochloride was approximately 71 nm. The particles were spherical and rectangular in shape. Moreover, the melting point of the nanoparticles decreased from 198.2°C to 196.3°C when compared to raw particle crystals. Furthermore, the agglomeration effect was also attenuated as a result of electrostatic repulsion among each particle when absorbed, and depositing on the inner wall of the gathering unit occurred under the electrostatic effect. Conclusion: Ultrasonic spray-assisted electrostatic adsorption is a very effective and continuous method to produce drug nanocrystals. This method can be applied to poorly water-soluble drugs, and it can also be a very effective alternative for industrial production. Once the working parameters are given, drug nanocrystals will be produced continuously.

The surface properties of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with various particle sizes were characterized by inverse gas chromatography (IGC). The disperse component gamma s(d) of surface free energy of TATB samples increased as temperature increased. The larger the particle size is, the quicker the increasing rate of the disperse component will be as the temperature increases. The gamma s(d) of the coarse TATB is the highest (193.2 mJ/m2) and that of the submicron TATB is the smallest (64.0 mJ/m2) at 353 K. Due to the different preparation processes and particle sizes, the samples show obviously different Lewis acid-base properties. Fine TATB can provide positive Lewis acid-base active sites and has higher acidity. The specific components of the adsorption of polar probes on the surface of the other three types of TATB were found to be endothermic owing to the strong hydrogen bond of inter- and intra-TATB molecules. Their surface acidity and basicity constants, K(a) and K(b) are negative.