Effect of barium hydrosilicates on the early hydration rate of Portland cement

We have studied the effect of a barium hydrosilicate-based modifier on the phase composition of Portland cement hydration products. The results demonstrate that the addition of a modifier containing barium hydrosilicates, silicic acid, and calcium carbonate makes it possible to reduce the nucleation rate of crystals of new phases during the induction period of the hydration process, increase alite (3СaO · SiO₂) hydration, and reduce the rate of aluminate phase (3CaO · Al₂O₃) hydration. The use of such a modifier increases the degree of cement hydration and the amount of calcium hydrosilicates and reduces the amount of forming portlandite and ettringite, thereby improving the mechanical properties and durability of the set cement.     

Photorefractive properties of composites based on polyvinyl alcohol,single-wall carbon nanotubes,and fullerene

Composites with photoelectrical, nonlinear optical, and photorefractive properties have been prepared. The composites consist of polyvinyl alcohol, single-wall carbon nanotubes, and fullerene C₆₀. Addition of C₆₀ with a long wavelength boundary near 630 nm resulted in an eight- to tenfold increase in both the quantum efficiency of generation of mobile hole charges and the photorefractive two beam gain coefficient measured at wavelengths exceeding 1000 nm (over an area of optical absorption of nanotubes). This is attributed to electron trapping by acceptor fullerene, which limits the regeneration of photogenerated charges and provides an increase in mobile hole charges.     

Corrosion and anodic oxidation of copper in 1-butyl-3-methylimidazolium bromide–copper(II) bromide ionic liquid

Using the gravimetric and polarization methods, the corrosion behavior of copper in 1-butyl-3-methylimidazolium bromide (BMImBr) ionic liquid in its pure state and with additions of CuBr₂ (from 0.4 to 1.2 mol kg^–1) has been investigated. It is found that the corrosion in naturally aerated BMImBr ionic liquid is accompanied by oxygen depolarization. Copper dibromide in BMImBr–CuBr₂ ionic liquid plays the role of an oxidant, and the rate of copper corrosion in this case is higher by about an order of magnitude than for the pure ionic liquid. The method of cyclic voltammetry shows that the anodic dissolution of copper in BMImBr–CuBr₂ ionic liquid proceeds via the EC mechanism. It is shown that the chemical-reaction rate of dissolving the surface layer and the rate of copper corrosion (according to gravimetric and polarization data) are comparable. Copper corrosion in the studied ionic liquid is accompanied by the effect of surface polishing, as is confirmed by the atomic force microscopy and profilography.     

Photorefractive and nonlinear optical properties of indium(III) tetra(15-crown-5)phthalocyaninate-based composites

Photoelectric, nonlinear optical, and photorefractive properties of hybrid composite materials based on polyvinylcarbazole (PVK) and indium(III) 2,3,9,10,16,17,23,24-tetra(15-crown-5)phthalocyaninate [(15C5)₄Pc]In(OH) are studied in detail. Field dependence of the quantum efficiency in a 7.8 μm-thick layer containing 5 at % [(15C5)₄Pc]In(OH) is measured. The best approximation of the quantum efficiency with Onsager’s equation corresponds to a quantum yield of thermalized electron-hole pairs φ₀ = 0.01 at initial separation r ₀ = 9.8 Å. Z-scan measurements in a nanosecond range showed that the electric susceptibility of [(15C5)₄Pc]In(OH) solution in tetrachloroethane (TCE) with a concentration of 7 × 10^?4 mol/L is χ⁽³⁾ = 1.34 × 10^?9 esu. The maximum coupling gain coefficient found for the material composed of PVK and 5 wt % [(15C5)₄Pc]In(OH) at an electric-field intensity of 200 V/μm is Γ = 80 cm^?1, and the difference between the coupling gain and absorption coefficients is Γ ? α = 70 cm^?1. The dependence of the coupling gain coefficient on the intensity ratio of interfering beams 1 and 2 (β = I ₁(0)/I ₂(0)) in a composite containing 3 wt % [(15C5)₄Pc]In(OH) is measured. An increase in β was attained by decreasing intensity of the signal beam I ₂(0) at constant intensity of the pump beam I ₁(0) = 0.15 W/cm² and E ₀ = 214 V/μm. Within the initial segment of the curve, the coupling gain coefficient increases from 30 to 60 cm^?1; then, the coefficient drops almost to the initial value. The data obtained show that the composite materials studied can be used in practice for correcting faded images. The combined analysis of the results obtained and similar data for gallium and ruthenium tetra-15-crown-5-phthalocyaninate complexes revealed the regularities in the change of the quantum yield of thermalized electron-hole pairs and the photorefractive coupling gain coefficient in a series of complexing metals: gallium(III), ruthenium(II), and indium(III). An increase in the molecular weight of the central metal atom is found to result in a substantial decrease in Γ and φ₀ due to the increase in the spin-orbit coupling constant.     

Modification of synthetic materials to reduce combustibility

The studies conducted demonstrated the effectiveness of using Phosdiol for reducing the combustibility of PE fibres and the small effect of PAN and PA fibre fire barriers. The oxygen index of flameproof fibrous polyester material was 27.5%, which allows assigning it to difficultly combustible polymers, and the strength of the fibre increases by 12–15%. __________ Translated from Khimicheskie Volokna, No. 1, pp. 35–38, January–February, 2006.     

Organic sulfur compounds in petroleum of the Arkhangel’sko-Tanaiskoe field

The structural-group composition of sulfur compounds in concentrates isolated under mild conditions by two-step extraction with acetonitrile and sulfolane from crude oil of the Arkhangel’sko-Tanaiskoe field was studied. With the use of a combination of up-to-date chemical and instrumental techniques, the structures of 130 organic sulfur compounds were determined in the concentrates, of which 30 were first found in petroleum.     

Production of low pour-point diesel fuels and high-purity paraffins from gas condensate

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, pp. 6–7, May, 1989.