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Oil in water (O/W) and water in oil (W/O) crude oil emulsions have caused many production safety hazards and environmental problems, which have attracted widespread attention. In this article, an amphiphilic nano demulsifier ZIF-8@CNTs was prepared by solvothermal method based on the metal-organic frameworks (MOFs) and carbon nanotubes (CNTs). Scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR) showed that ZIF-8@CNTs were grape dendritic, and ZIF-8 was successfully combined with OX-CNTs. Thermogravimetric analysis (TGA) showed that ZIF-8@CNTs had good thermal stability. The demulsification test showed that the demulsification rate could reach 99.4% when ZC-1 was added at 500 mg/L for 30 min at room temperature. The demulsification mechanism was studied by interfacial tension and interfacial activity experiments. [ABSTRACT FROM AUTHOR]

In this study, a new type of highly efficient and recyclable magnetic-fluorine-containing polyether composite demulsifier (Fe3O4@G-F) was synthesized by the solvothermal method to solve the demulsification problem of oil–water emulsion. Fe3O4@G-F was successfully prepared by grafting fluorinated polyether onto Fe3O4 and graphene-oxide composites. Fe3O4@G-F was characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Taking the self-made crude-oil emulsion as the experimental object, the demulsification mechanism of the demulsifier and the influence of external factors, such as the temperature and pH value, on the demulsification performance of the demulsifier are discussed. The results show that the demulsification efficiency of the Fe3O4@G-F emulsion can reach 91.38% within 30 min at a demulsifier dosage of 750 mg/L, pH of 6, and a demulsification temperature of 60 °C. In neutral and acidic environments, the demulsification rate of the demulsifier is more than 90%. In addition, Fe3O4@G-F has been proven to have good magnetic effects. Under the action of an external magnetic field, Fe3O4@G-F can be recycled and reused in a two-phase system four times, and the demulsification efficiency is higher than 70%. This magnetic nanoparticle demulsifier has broad application prospects for various industrial and environmental processes in an energy-saving manner. [ABSTRACT FROM AUTHOR]

In this study, a carbon‐based nanodemulsifier (ZIF‐8@CNS) was prepared in order to lessen the harmful effects of crude oil emulsion on mechanical equipment and the environment and to provide a green and efficient demulsifier. A novel hydrophilic/lipophilic carbon‐based nanodemulsifier ZIF‐8@CNS was prepared by solvothermal method using ZIF‐8 and carbon nanospheres (CNS) as raw materials. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT‐IR) showed that ZIF‐8@CNS was successfully compounded. The interfacial activity experiment showed that the carbon nanospheres combined with ZIF‐8 had better hydrophilic and lipophilic balance and were more easily distributed at the oil‐water interface. The demulsification experiment of water‐in‐toluene emulsion with water content of 1 % was carried out. The results showed that when the dosage of ZIF‐8@CNS with 10 % carbon content was 300 mg/L, the residual water content in the emulsion oil phase was only 0.09 % within 15 min at room temperature. In addition, we propose a possible demulsification mechanism of the demulsifier. ZIF‐8@CNS is environmentally friendly and an effective oil‐water phase separation material with broad application prospects. [ABSTRACT FROM AUTHOR]

In order to reduce the mechanical sensitivity of cyclotrimethylenetrinitramine (RDX) and improve its energy density, spherical RDX/PMMA/NC composite particles were prepared by spray drying method, selecting polymethyl methacrylate (PMMA, hydrocarbon binder) with excellent mechanical properties and nitrocellulose (NC, energy-containing binder) with higher density as the desensitizing shell material, RDX as the core material. PMMA/NC composite particles of the same component were prepared by a simple solvent evaporation method at the same time. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC), respectively. Moreover, the safety performance has been qualitatively tested and analyzed through impact sensitivity and friction sensitivity. The results show that the addition of NC/PMMA binder would not change the original crystal structure of RDX, and the RDX/NC/PMMA composites fabricated by spray drying presented spherical particles with uniform distribution and smooth surface. The Tp0 of RDX/NC/PMMA composite particles increased from 220.3°C to 228.2°C, improving the thermal decomposition performance. The H50 rose from 29.32 cm to 84.3 cm, and the probability of friction explosion decreased from 96% to 8%, significantly enhancing the safety performance. In short, the RDX/NC/PMMA composites prepared via the spray drying method and the improvement of their performance have positive significance for the development of explosives in pursuit of high energy and low sensitivity. [ABSTRACT FROM AUTHOR]

In this paper, the optimal temperature in an HMX spray-drying process was determined by molecular dynamics simulations and verified using experiments. Using the optimal spray-drying temperature determined by simulations, spherical β-HMX with a uniform particle size distribution was obtained by spray-drying. Performance characterization and thermal analysis of β-HMX were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The impact sensitivity of β-HMX was also measured and analyzed. The molecular dynamics simulations and experimental results both indicated that the optimum spray-drying temperature of HMX was 57°C. At this temperature, an HMX particle diameter range of 1 µm – 5 µm was obtained, and the particles tended to be smooth spheroids. Compared with raw HMX, the Tp0 and critical temperature of thermal explosion of HMX-1 increased by 0.9°C and 0.94°C, respectively. The characteristic drop height of impact sensitivity increased by 32% from 32.05 cm to 42.28 cm. [ABSTRACT FROM AUTHOR]

We proposed with excitement a novel molecular co-assembly (MCSA) that can effectively overcome the agglomeration of energetic materials. Through the coordinated self-assembly of polymethyl methacrylate-polyvinyl acetate (PMMA-PVA) with honeycomb-like structure and nanoparticles, a controlled and orderly distribution of nitroamine explosive (cyclotetramethylenetetranitramine, HMX; cyclotrimethylenetrinitramine, RDX; and hexanitrohexaazaisowurtzitane, CL-20) structure was achieved, above all, resolving the agglomeration problem availably. The modification ability of PMMA to RDX, HMX, and CL-20 at different temperatures was simulated by Materials Studio, which provided guidance for the ambient temperature of collaborative self-assembly. In order to compare the priority of the morphology and performance, RDX/PMMA-PVA, HMX/PMMA-PVA, and CL-20/PMMA-PVA composite particles with the same PMMA content were also fabricated by water suspension coating method, respectively. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier-transform infrared (FT-IR) spectra, and differential scanning calorimeter (DSC). Moreover, the safety performance was analyzed by qualitative testing of impact sensitivity and friction sensitivity. The solid spherical PBX prepared via collaborative self-assembly all exhibited a perfect spherical structure, smooth, and flat coating, without any agglomeration. They had the same crystalline structure as the uncoated explosives, simultaneously demonstrating lower impact sensitivity and higher energy performance. The application of collaborative self-assembly technology has broken through the key technical bottleneck of the shell material being easy to form a separate phase in the desensitization coating of explosives, availably resolved the problems of particle exposure and low coverage during the coating, thus possessing vital significance for reference in the design and fabrication of PBXs with core-shell structure. [ABSTRACT FROM AUTHOR]

To improve the safety of ammonium nitrate explosives, a one-step method involving the formation of CL-20/TATB/VitonA composite microspheres using spray drying is presented. The crystal morphology, particle size, crystal structure, thermal properties, and sensitivity of raw materials of CL-20 and TATB, CL-20/VitonA particles, and CL-20/TATB/VitonA microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and impact and friction sensitivity tests. The SEM results show that the prepared CL-20/TATB/VitonA composites with micro-/nanoscale grain size have a good spherical shape. Thermal analysis data show that TATB coating enhances the thermal stability of CL-20/VitonA. The impact and friction sensitivity results show that superior mechanical properties of these composite microspheres could be maintained. Obviously, this approach is an effective desensitization technique to prepare composite microspheres for explosives. [ABSTRACT FROM AUTHOR]

In this study, a novel spray drying-assisted self-assembly (SDAS) technology was proposed to prepare submicron elemental explosives with good morphology, uniform dispersion, and low sensitivity and spherical submicron RDX, HMX, and CL-20 particles without soft agglomeration were fabricated via such a method. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). Moreover, safety performance was analyzed by qualitative testing of impact sensitivity and friction sensitivity. The XRD analysis demonstrated that HMX and CL-20 refined by SDAS maintained the crystal structure of β-HMX and ε-CL-20 before and after refinement, whereas the HMX crystal structure after spray recrystallization refinement was transformed from β-HMX to α-HMX. The DSC results indicated that the thermal decomposition peak temperature of the three particles refined by the SDAS technology had a minimum advancement, and the thermal stability of the particles was relatively superior. More importantly, the H50 of the RDX, HMX, and CL-20 refined by this novel method was increased to 48.3 cm, 44.6 cm, and 31.1 cm, and the probability of friction explosion was decreased to 62%, 62%, and 80%, respectively, thus significantly improving the safety performance as compared with the sample refined by spray recrystallization. [ABSTRACT FROM AUTHOR]

Nanoparticle-stacked 1,1-diamino-2,2-dinitroethylene (FOX-7) microspheres were successfully prepared by spray-drying, and rod-shaped FOX-7 was obtained by the solvent/nonsolvent method for comparison. The microstructure features of samples were characterized using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD), and the thermal properties were also investigated by differential scanning calorimetry (DSC). From the SEM analysis, the particle size of the rod-shaped FOX-7 is about 10 μm, whereas FOX-7 microspheres having a particle size ranging from 1 to 5 μm are formed by stacking nanoparticles with size of 100-250 nm. The crystal form of the samples prepared by the two methods did not change. The thermal performance test results showed that the rd-shaped FOX-7 had no significant change compared with the raw FOX-7, while the nanoparticle-stacked FOX-7 microspheres had higher thermal stability. [ABSTRACT FROM AUTHOR]

Herein, a green process for preparing nano-HMX, mechanical demulsification shearing (MDS) technology, was developed. Nano-HMX was successfully fabricated via MDS technology without using any chemical reagents, and the fabrication mechanism was proposed. Based on the “fractal theory,” the optimal shearing time for mechanical emulsification was deduced by calculating the fractal dimension of the particle size distribution. The as-prepared nano-HMX was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). And the impact sensitivities of HMX particles were contrastively investigated. The raw HMX had a lower fractal dimension of 1.9273. The ideal shearing time was 7 h. The resultant nano-HMX possessed a particle size distribution ranging from 203.3 nm to 509.1 nm as compared to raw HMX. Nano-HMX particles were dense spherical, maintaining β-HMX crystal form. In addition, they had much lower impact sensitivity. However, the apparent activation energy as well as thermal decomposition temperature of nano-HMX particles was decreased, attributing to the reduced probability for hotspot generation. Especially when the shearing time was 7 h, the activation energy was markedly decreased. [ABSTRACT FROM AUTHOR]