Thermoelastic martensitic transformations in single crystals with disperse particles

The results of investigations into the influence of disperse particles on the temperatures of martensitic transformations as well as values of thermal and mechanical hysteresis in the FeNiCoAlTa, CoNiGa, NiFeGa, TiNi single crystals are reported. It is shown that the disperse particles are responsible for refining martensitic crystals and changing their fine twin structure as compared with the monophase state. This, in turn, affects the values of thermal and mechanical hysteresis and the temperature range of superelasticity.     

Synthesis and characterization of the Pt/Al2O3 systems modified with group III (Ga) and Group IV (Ge,Ti, and Zr) elements in the combined conversion of propane and n-Heptane

Under the conditions of a joint reaction of propane and n-heptane at temperatures of 460–520°C and a pressure of 0.35 MPa, the conversion of propane and the concentration of C₇₊ aromatization products on platinum-containing catalysts modified by Group III (Ga) and Group IV (Ge, Ti, and Zr) elements were higher than those on an unmodified Pt/Al₂O₃ sample. This is explained by a change in the aprotic acidity of the catalysts as a result of the support modification. The sample with the addition of gallium was most active. A plausible reason for this is the conversion of hydrocarbons at active sites that consist of Pt and Ga, which were formed upon catalyst activation. It is believed that gallium adjacent to platinum in an ionic form on the support surface acts as an aprotic acid site.     

Use of polysulfides of alkali and alkaline-earth metals to obtain highly dispersed sulfur

Possibilities of obtaining polysulfides of alkali and alkaline-earth metals in aqueous solutions were considered. The composition of the polysulfides and their concentration in solutions were found. The efficiencies of application of highly dispersed sulfur, produced from calcium polysulfide, and colloid sulfur as a fungicide were compared.     

Synthesis and study of Ru–Ba–Cs/Sibunit ternary catalysts for ammonia synthesis

Ru–Ba–Cs/Sibunit ternary catalysts were synthesized. Their activity in ammonia synthesis and the thermal stability of the support in a reducing atmosphere at elevated temperature depend on the molar ratio of the promoters. The results of studies using physical methods suggest that cesium predominantly interacts with the support, acting as an electronic promoter, whereas barium is a structural promoter. The synergistic action of the promoters at increased barium content of the catalyst was revealed. The highest activity in ammonia synthesis, 34.5 mL_NH3 g_cat ^–1 h^–1, was reached for the 4% Ru–10.8% Ba–2.6% Cs/Sibunit catalyst.     

A new class of pressure-sensitive adhesives based on interpolymer and polymer-oligomer complexes

On the basis of previous concepts concerning the molecular nature of pressure-sensitive adhesion, a simple method of preparing new adhesives with the desired mechanical and adhesive behavior and water-absorbability via mixing of nonadhesive polymers has been developed. Pressure-sensitive adhesion is related to the combination of a high energy of cohesion and a large free volume, which leads to a high molecular mobility. This method is based on the formation of interpolymer or polymer-oligomer complexes during mixing of macromolecules capable of hydrogen, electrostatic, or ionic bonding. In interpolymer complexes, a high cohesion results from the formation of bonds between macromolecules carrying complementary groups in main chains, whereas free volume is related to defectiveness of the resulting network and formation of loops. In complexes formed by a high-molecular-mass polymer and an oligomer carrying complementary reactive groups at ends of short chains, a high energy of cohesion is related to their interaction with mainchain functional groups of the polymer, whereas a relatively large free volume is associated with the length and flexibility of intermacromolecular crosslinks via oligomer chains. The adhesive and viscoelastic properties of adhesives and their water absorbability are regulated by changes in the composition of mixtures of a film-forming polymer with a polymer or oligomer crosslinker and a plasticizer. In this case, an increase in cohesive strength is achieved owing to an increase in the crosslinker concentration, while the enhancement of free volume is ensured by the increasing plasticizer content in the blend. Adhesive materials capable of adherence to wet substrates, hydroactivated adhesives, and adhesion moisture sorbents have been prepared for the first time.