Žurnal prikladnoj himii

Synthesis of ultradisperse spherical ZnO powders was accomplished by spray solution combustion, employing four distinct fuels, namely methenamine, glycine, urea, and citric acid. Using X-ray diffraction analysis, scanning electron microscopy, and low-temperature nitrogen adsorption, the impact of the main process parameters (composition and concentration of fuel, temperature and rate of the carrier gas flow) on the structure and morphology of ZnO particles was demonstrated. A synthesis temperature of 700°C was found to be sufficient to generate crystalline ZnO with a homogeneous phase composition, regardless of the type and amount of fuel. It was shown that the initial pH of the precursor solution does not affect the formation of the ZnO phase. At rates of carrier gas flow above 4 L min–1, the presence of by-products is detected. It has been determined that the excess and type of fuel significantly affect the morphology of the synthesized ZnO microspheres and can be used to control the technological characteristics of the powder and the kinetics of sintering.

The paper deals with the synthesis and study of mixed (unsymmetrical) 1,4-butanediol diesters of petroleum acids and aliphatic fatty acids (С6–С8). High yield of the target product (90.3%) was reached under the following conditions: temperature 110–120°С, catalyst amount 1.3 wt % (based on the acid), acid : alcohol molar ratio 2 : 1.4. The physicochemical parameters and structures of the products were determined. The mixed 1,4-butanediol esters obtained are well compatible with polyvinyl chloride, forming colorless elastic compounds. The diesters were tested as antioxidants enhancing the thermal oxidation resistance of diesel fuel. The amount of the precipitate formed by oxidative polymerization and polycondensation of diesel fuel due to the presence of heteroatomic compounds decreases from 4.6 to 1.0 mg/100 mL fuel on adding 0.004 wt % diesters prepared.

The impact of operational conditions for carrying out methyl methacrylate suspension polymerization during stabilization of the system with dispersants of different chemical natures: poly-2-acrylamido-2-methylpropanesulfonic acid and Mg(OH)2, was studied. The role of the contribution of the chemical nature of the dispersant, which reduces the interfacial tension between the monomer and aqueous phases, to the particle size distribution of the polymer particles is shown. When polymerizing methyl methacrylate in the presence of water-insoluble Mg(OH)2, the interfacial tension diminishes, which brings about the formation of a highly dispersed polymer without the use of high-speed dispersion of the reaction mass.

The effect of extrusion parameters on the characteristics of nanocomposites based on polypropylene random copolymer and ethylene–propylene block copolymer with carbon black and aluminum nanoparticles and calcium stearate was studied. Printex XE 2-B carbon black with the nanoparticle size of 18–20 nm was used. Exхelor PO 1020 compatibilizer was used for improving the compatibility of the blend components. Introduction of the above fillers allows obtaining a multifunctional nanocomposite that exhibits high levels of electrical conductivity, adhesion to metals, and thermal conductivity and can be processed by pressure casting and extrusion. The effect of the temperature conditions in the extruder material cylinder on the breaking stress and relative elongation of the nanocomposites was considered. The optimum temperature conditions of the extrusion, ensuring relatively high properties of the composite, were determined.

The impact of the amount of water-swellable filler sodium carboxymethylcellulose of Polycell-9B grade (particle size 1.0–2.0 mm) on the complex of physical and mechanical properties of limited swelling rubbers based on nitrile butadiene rubber of BNKS-28 AMN grade with a sulfur vulcanizing system was studied. The composition with a ratio of the rubber compound without swelling filler to sodium carboxymethylcellulose was varied in the range (65–35) : (35–65) (wt. parts). It was established that the introduction of a swelling filler into the rubber compound has virtually no effect on the time to achieve the optimal vulcanization time and is 10 min at a temperature of 170°C. It was shown that the introduction of sodium carboxymethylcellulose leads to a decrease in the deformation-strength properties of rubbers, however, the strength characteristics of modified rubbers allow the use of the developed rubber compositions for the manufacture of sealing elements of water-swellable packers. It was revealed that with an increase in the proportion of the swelling filler, sodium carboxymethylcellulose, the vulcanizate exhibits a higher sorption capacity in aqueous media with different pH.

The effect of modifying additives of polyphenylene sulfone or a nonwoven polyamide material on the thermal and mechanical properties of carbon fabric/epoxy resin polymer composite materials prepared by vacuum forming and vacuum infusion was studied. The addition of 10 wt % polyphenylene sulfone leads to slight improvement of the mechanical properties of the composite material, whereas introduction of the nonwoven material leads to a 15% decrease in the compression strength and to a 6% decrease in the interlayer shear strength. The specific peel work increases by 15 and 270% for the composites modified with polyphenylene sulfone and nonwoven cloth, respectively. Introduction of 4 wt % nonwoven material enhances the fracture toughness of the polymer composite material by a factor of 3.7.

The equilibrium parameters of steam isobutanol reforming were calculated. These include the H2 yield, selectivity with respect to carbon-containing gases, and feed conversion. The calculated data, on the whole, agree with the published data and experimental values of the isobutanol conversion and yield of isobutyraldehyde and higher alkanes on Ni–Co catalysts supported on biochars prepared by hydrothermal carbonization of cellulose. On the other hand, the calculated yields of H2, СО, and СН4 disagree with the experimental data, which suggests that the equilibrium in the experiments on the steam isobutanol reforming on this catalyst is not attained. Feeding a homogeneous mixture of water, isobutanol, and ethanol into the reactor at 700°С allows the Н2 yield to be increased from 58 to 66% and the water conversion, from 58 to 76% compared to the steam reforming of isobutanol without ethanol. The addition of ethanol allows the coking to be significantly reduced and the H2 and СО yield higher than 90% at 900°С to be reached.