Influence of External Conditions on the Relation between the Physical and Chemical Processes in the Thermodegradation of Plasticized Poly(Vinyl Chloride)

The heat-induced loss of plasticizer from and dehydrochlorination of poly(vinyl chloride) plasticized with dioctyl phthalate is studied by thermogravimetric analysis, IR spectroscopy, and colorimetry. Specific features and general regularities of the processes at high (200–320°C) and medium (100–132°C) temperatures are established. It is shown that the dehydrochlorination and oxidation processes dominate in confined space whereas, in unconfined space, plasticizer is lost largely through evaporation. The activation energies of the initial stages of the processes are determined.     

Effect of phosphate doping on electric properties and chemical stability of Ba<Subscript>4</Subscript>Ca<Subscript>2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>11</Subscript> protonic conductor

Conductivity of perovskite phosphate–substituted solid solutions of Ba₄Ca₂Nb_{2 –x} P _x O₁₁ (0.0 ≤ x ≤ 0.5) was studied as a function of temperature, partial pressure of oxygen and water vapors. It is proved that the studied systems are protonic conductors at the temperatures below 600°C in the atmosphere with elevated content of water vapors (pH₂O = 1.92 × 10^–2 atm). Introduction of the tetrahedral [PO₄] group in the complex oxide matrix of Ba₄Ca₂Nb₂O₁₁ results in an increase in the oxygen–ionic (dry air, pH₂O = 1.91 × 10^–4 atm) and protonic conductivities (wet air, pH₂O = 1.92 × 10^–2 atm). Is it found that the doping causes a considerable increase in chemical stability of phases with respect to carbon dioxide.     

Effect of F<Superscript>–</Superscript>-doping on the transport properties of perovskite-like complex oxides

The structural and electric characteristics of fluorine-substituted complex oxides obtained by anion doping based on Ba₂CaNbO_5.5 and Ba₂In₂O₅ matrices were compared. The mobility of ion charge carriers was found to depend on the concentration of the dopant anion and oxygen vacancies and the degree of disordering of the latter.     

Extraction of acetic acid by binary extractants

Interface distribution of acetic acid has been studied in systems with binary extractants, namely, trioctylmethylammonium di(2-ethylhexyl)phosphate, di(2-ethylhexyl)dithiophosphate, and dinonylnaphthalenesulfonate. It has been determined that, with the increase in the strength of the organic acid involved in a binary extractant, the extraction ability of a monocarboxylic acid decreases and addition reaction with the formation of extracted compound of R₄NA · HX_(o) composition becomes the dominant mechanism of extraction.     

A new approach to nucleation of cavitation bubbles at chemically modified surfaces

Cavitation at the solid surface normally begins with nucleation, in which defects or assembled molecules located at a liquid-solid interface act as nucleation centers and are actively involved in the evolution of cavitation bubbles. Here, we propose a simple approach to evaluate the behavior of cavitation bubbles formed under high intensity ultrasound (20 kHz, 51.3 W cm(-2)) at solid surfaces, based on sonication of patterned substrates with a small roughness (less than 3 nm) and controllable surface energy. A mixture of octadecylphosphonic acid (ODTA) and octadecanethiol (ODT) was stamped on the Si wafer coated with different thicknesses of an aluminium layer (20-500 nm). We investigated the growth mechanism of cavitation bubble nuclei and the evolution of individual pits (defects) formed under sonication on the modified surface. A new activation behavior as a function of Al thickness, sonication time, ultrasonic power and temperature is reported. In this process cooperativity is introduced, as initially formed pits further reduce the energy to form bubbles. Furthermore, cavitation on the patterns is a controllable process, where up to 40-50 min of sonication time only the hydrophobic areas are active nucleation sites. This study provides a convincing proof of our theoretical approach on nucleation.     

Organosilicon Compounds in the Synthesis of Linear and Heterocyclic Products

Organosilicon and carbofunctional organosilicon compounds were reacted with chloro(chloromethyl)dimethylsilane, disilaethane, and disilaethene to obtain previously unknown linear and heterocyclic products.