Vol 89, No 10 (2016)

Published data on the phase diagram of the lithium–germanium system, on the thermodynamic properties of Li–Ge alloys, on their electrochemical behavior in various media, and on prospects for using them in lithium–ion batteries and in other chemical current sources are analyzed.

Phosphorus oxide structures were synthesized on the surface of porous gamma alumina, with phosphorus oxychloride and water vapors used as reagents for successive and alternating (up to four times) treatment of a solid-phase matrix by the molecular layering method with in situ monitoring of the process. It was shown that this procedure yields a double-phase system constituted by a core (aluminum oxide) and shell (amorphous phosphorus oxide layer) with a prescribed chemical composition and structure with characteristics dependent on the number of molecular layering cycles. With increasing treatment rate (from 1 to 4) of the solid-phase matrix with halide and water vapors, the concentration of phosphorus in the samples steadily grows. In the process, the specific surface area, pore volume, and pore size in the double-phase system being formed become smaller. The results obtained in the study are of interest for development of catalytic, sorption, and other functional systems of the core–shell type.

Effect of synthesis parameters on the characteristics of expanded graphite were studied. The starting sample, intercalated graphite, was treated by several methods: thermal shock (400, 1000°C) and programmed heating (400–700°C). The samples were examined by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, and low-temperature nitrogen adsorption. The programmed-heating method yields better texture characteristics as compared with the thermal shock. The programmed-heating method was used to obtain high-quality expanded graphite with high specific surface area (299 m² g^–1) at a comparatively moderate temperature of 400°C.

Powders were synthesized in the yttrium oxide + zinc oxide system doped with europium oxide by the method of redox combustion of a mixture of yttrium, zinc, and europium nitrates in the presence of saccharose (fuel). The structure and the physicochemical and luminescent properties of the particles being formed and of a ceramic on their basis were examined.

Lithium-riched cathode material for lithium-ion batteries, Li_1.17Ni_0.12Co_0.13Mn_0.58O₂, was synthesized via crystallization from a solution of metal acetates, followed by a thermal treatment of the material obtained as a powder. The phase, elemental, and granulometric compositions of the material were examined, as well as the morphology of the powder particles obtained. The discharge capacity of the material in relation to the charging voltage was found from the results of electrochemical tests, and endurance tests were performed. The discharge capacity upon 85 charge/discharge cycles at voltages in the range 2.8–4.8 and a current of 0.1C was about 180 mA h g^–1.

Results are presented obtained in tests of various homogeneous and heterogeneous catalysts in a synthesis of solketal (2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane). It is shown that, all other conditions being the same, the highest catalytic activity is observed for sulfuric acid and beta zeolite. Data are presented on how the equilibrium constant of the reaction of glycerol ketalization depends on temperature. A technological scheme of the process for synthesis of solketal is suggested and its description is presented.

The kinetics of sorption of vapor over aqueous and aqueous-alcoholic solutions of potassium iodide and potassium iodine–iodide and over crystalline iodine onto chitosan powder or film was studied. The vapor diffusion coefficients in the initial and final sorption steps were calculated from the data obtained. For all the chitosan–sorbate vapor systems studied, the mass transfer relationships are not described by Fick’s law and are characterized by anomalous sorption kinetics. The properties of chitosan powder after the uptake of the sorbate vapor were evaluated by electronic and IR spectroscopy, X-ray diffraction, and differential thermal and thermal gravimetric analysis. Sorption of iodine-containing vapor onto the polymer is accompanied by complexation of the components. The iodine–chitosan complexes are stable in storage and resistant to heat treatment. The results obtained served as a basis for developing a procedure for preparing kinetically and thermally stable powdered iodinated chitosan derivatives.

A series of structurally similar poly(o-hydroxy amides), homo- and copolymers with different bridging fragments in the amine component, were synthesized. The heat resistance and electrophysical parameters of powdered polymer samples, of micrometer-thick films formed on substrates from reaction solutions of these polymers, and of films of photosensitive formulations based on them, containing photosensitive diazonaphthalenone component, were studied. Introduction of hexafluoropropane fragment into the macromolecule enhances the heat resistance of the polymer (powders and films) and decreases the dielectric permittivity of the films, compared to the reference poly(o-hydroxy amide) derived from 3,3'-dihydroxy-4,4'-diaminodiphenylmethane. The tetramethylsiloxane fragment considerably decreases the heat resistance of polymer powders and films, but improves the dielectric parameters of the coatings. Introduction of the diphenyl oxide fragment into poly(o-hydroxy amide) complicated the formation of high-resolution microrelief in films of the photosensitive formulation owing to a sharp decrease in the solubility of the films in alkaline solutions. Suitable electrophysical parameters and thermal characteristics of the polymers obtained, their capability for film formation, compatibility with photosensitive components, and possibility of the formation of high-resolution positive microrelief upon exposure allow these polymers to be recommended as promising polymeric binders for highly heat-resistant organic dielectrics and protective coatings for microelectronics.

The effect that mechanical treatment of SKS-30 ARK latex by mixing in a gap between coaxial cylinders exerts on the latex resistance to an electrolyte and on the polymer yield in coagulation with two types of coagulants, sodium chloride and N,N-dimethylaminopropyl carboxy betaines derived from vegetable oil fatty acids, was studied. Such treatment decreases the rapid coagulation threshold and increases the coagulum yield. The effect is caused by partial breakdown of hydrate shells of particles as a result of mechanical action in a shear stress field.

A novel hydrogel based on chitosan–poly(acrylamide-co-acrylic acid) (CAA) with different formulations were synthesized by the effect of gamma radiation. The magnetic CAA hydrogels were also synthesized and characterized by using different techniques, e.g., TEM and XRD. The prepared hydrogels and magnetic hydrogel nanocomposite were utilized for in situ cobalt nanoparticle preparation and employed as a reaction media in catalytic reduction of 2-nitrophenol (2-NP), to 2-aminophenol (2-AP). The experimental parameters that affect the reduction rates such as temperature and amount of catalyst were also, investigated.

Drilling fluids are widely used in the drilling of deep wells to clean and transport the rock cuttings, maintain the sidewall of oil well, lubricate and cool the drilling bit, and control the formation pressures. The present work aims at improving the high-temperature resistance of water-based drilling fluid by using the newly synthesized fluid loss additive named PAASD. This copolymer was obtained through the solution polymerization of four kinds of monomers. The synthesis conditions with the optimal API filtration were studied by single synthetic experiment, and the chemical structure of final product was confirmed by FTIR spectroscopy. The target product was carried out with thermal stability analysis, rheological property, filtrate property, temperature resistant capacity, salt tolerance capacity, micro-crosslink structure property, particle size distribution and the compatibility performance experiment. The results showed that PAASD was an efficient fluid loss additive, and the API filtration of fresh water drilling fluid containing 2% PAASD was only 5.2 mL, it was 10.6 mL after aging at the condition of 200°C and 16 h. Besides, PAASD has a good thermal stability, salt tolerance, and it could improve the rheological property of drilling fluid system obviously. Therefore, it could be used as fluid loss additive of water-based drilling fluid in salty and high-temperature environment.

The effects of various compatibilizers on thermal, mechanical and morphological properties of 50/50 polypropylene/polystyrene blends were investigated. Various compatibilizers, polystyrene-(ethylene/butylenes/ styrene) (SEBS), ethylene vinyl acetate (EVA), polystyrene-butylene rubber (SBR) and blend of compatibilizers SEBS/PP-g-MAH, EVA/PP-g-MAH, and SBR/PP-g-MAH were used. Differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, scanning electron microscopy, microhardness, and Izod impact strength were adopted. It was found that the influence of various compatibilizers was appeared on all the properties studied. The properties of the blends compatibilized with SEBS, EVA, and SBR are very distinct from those of blends compatibilized with blend of compatibilizers. Results show that compatibilized blends with the blend of compatibilizers EVA/PP-g-MAH, SBR/PP-g-MAH, and SEBS/PP-g-MAH or SBR were relatively more stable than the uncompatibilized blend and blend compatibilized with SEBS or EVA. The compatibilizer does not only reduce the interfacial tension or increase the phase interfacial adhesion between the immiscible polymers, but greatly affects the degree of crystallinity of blends.

Lithium recovery from lepidolite was studied experimentally, and a sulfuric acid procedure for lithium recovery was suggested. It ensures the maximal degree of lithium recovery from this mineral at minimal power consumption. The suggested procedure creates prerequisites for large-scale involvement of lepidolite into lithium metallurgy, taking into account large amount of developed lepidolite deposits and steadily growing demand for lithium products.