Structure and property of propellant based on nitroglycerine/glycerol triacetate mixed plasticizers: molecular dynamics simulation and experimental study.

Molecular dynamics simulation has been used to investigate the influence of nitroglycerine (NG)/glycerol triacetate (GTA) mixed plasticizers on the plasticizing ability of nitrocellulose (NC) binder in solid propellant. The radial distribution function and binding energy indicated that NC/plasticizers blends showed stronger intermolecular interaction of van der Waals and hydrogen bonds. The mean-squared displacements of plasticizers and volume distribution revealed that the mobility of plasticizer GTA in the NC polymer binder was higher than that of NG. Then, the mechanical properties of the propellant based on NG/GTA mixed plasticizers were investigated systematically using experimental and simulation calculation method. The results suggested that the ductility of propellant based on NG/GTA mixed plasticizers was improved, implying that NG/GTA mixed plasticizers have a higher plasticizing efficiency for NC. Furthermore, we conducted experimental studies on the effects of NG/GTA mixed plasticizers on the energy and combustion properties of propellants. It was shown that NG/GTA mixed plasticizers could enhance the combustion efficiency of propellants effectively at low pressures. These computational and experimental studies provided guidance for the application of NG/GTA mixed plasticizers in high-performance propellants.

Synthesis of Different Shapes ZnFe2O4­BiOCl Nanocomposites for Photocatalytic Reduction of CO2 in Cyclohexanol.

Nanosheet and hierarchical microsphere nanostructures of ZnFe2O4­BiOCl nanocomposites with various ZnFe2O4 contents were prepared through hydrothermal deposition method. The morphology and structure of the as-prepared samples were systematically characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, Brunauer-Emmert-Teller method, and photoluminescence spectra. The photocatalytic activities of the two different shapes of ZnFe2O4­BiOCl composites have been evaluated by photocatalytic reduction of CO2 in cyclohexanol under UV light irradiation. The results showed that cyclohexanol was oxidized to cyclohexanone (CH), and CO2 was reduced and then reacted with cyclohexanol to produce cyclohexyl formate (CF). The ZnFe2O4­BiOCl composites with different shapes showed much higher CF and CH yields than those of pristine BiOCl and mechanically mixed samples, respectively. When the ZnFe2O4 content in the composites reached 9%, two different shapes of ZnFe2O­BiOCl composites both achieved the highest photocatalytic activities. In contrast, the activities for photocatalytic reduction of CO2 in cyclohexanol over hierarchical microsphere ZnFe2O4­BiOCl composites were higher than those of nanosheet structure samples. The higher activities over hierarchical microsphere composites could be attributed to its unique hierarchical structure, large illumination area, and low Photoluminescence (PL) emission intensity, which were beneficial for the separation of photogenerated charge carriers. This work provided a novel approach for the design and construction of highly efficient photocatalyst and reaction system for photoreduction of CO2.