Polymer Science, Series D最新文献

Ethylbenzene hydroperoxide (EBOOH) is used to produce propylene oxide, a raw material in the synthesis of polyurethane adhesives. The catalytic activity of magnesium 2-ethylhexanoate (Mg(EH)₂ in the oxidation of ethylbenzene has been experimentally demonstrated. As a result of quantum chemical modeling (B3PW91/x2c-TZVPall), the thermodynamic possibility of the formation of intermediate adducts of Mg(EH)₂ with the components of the reaction system has been established. It has been established that the strength of the O–O bond in gauche-EBOOH in the adduct gauche-EBOOH@Mg(EH)₂ is lower than in free gauche-EBOOH.

The effect of flame retardants on the physical and mechanical and thermo-oxidative properties of composite materials based on thermoplastic elastomers is studied. It is shown that a composition based on a thermoplastic elastomer with a selected concentration of organobentonite and brucite additives possesses a set of flame-retardant properties including thermo-oxidative stability by the time of oxidative induction in comparison with other studied compositions.

The possibility of using atactic polypropylene as the main component of thermoplastic elastomers was investigated. It was shown that dynamically vulcanized mixtures of atactic polypropylene and ethylene–propylene–diene rubber have good deformation characteristics, reduced hardness, and low residual elongation.

Some aspects of potential protection against corrosion processes with natural compounds are considered. The prospects of using wood-processing waste as anticorrosion agents (corrosion inhibitors based on plant extracts) are discussed. It is shown that the combined action of plant polyphenols and environmentally friendly polyvinyl alcohol allows one to effectively prevent the development of corrosion processes on the surface of iron.

The results of an experimental evaluation of the influence of the geometric form of the tubes used for supplying a binder under the molding of parts using vacuum infusion on the flow uniformity of the binder front and on the phase composition of a composite material have been presented. The epoxy binder and basalt fabric were used as initial materials. Three types of tubes for supplying the binder have been considered, namely, regular, spiral, and special (in the form of a distribution stripe). We have presented the schemes of their installation, the patterns of the binder front movement, the results of an expert evaluation of the quality of the impregnation process, and the results of determining the phase composition and interlaminar shear strength. It has been established that the use of a spiral tube and distribution stripe makes it possible to reduce the difference in the phase composition of the basalt–plastic at the sites of installation of the tubes for the input and output of binders makes it possible to obtain the highest values of interlaminar shear strength.

Using literature data, a model was developed to predict the kinetics of drug’ desorption from hydroxypropyl-methylcellulose-based tablets at different water stirring rates. When the tablet comes into contact with a gastric juice, the polymer swells to form a gel-like shell, which prevents the transfer of gastric juice into the tablet and determines the rate of drug release into the human body. We used an equation that describes the kinetic dependences of drug desorption in the coordinate system of a conditional time equal to the square root of the observation time. Dependence of the equation coefficients on the stirring speed was established, which made it possible to obtain a model for predicting the kinetics of drug desorption from the time of contact with water and the water stirring speed.

Experimental results for the long-term full-scale climatic testing of aviation polysulfide and VITEF-1B, VGM-L, VIKSINT U-20-99, and VGF-2M polysiloxane grade sealing materials are presented. The testing have been carried out under open conditions of humid tropical climate characterizing Wanning (Hainan Island, China) and moderately warm climate characterizing Gelendzhik. In order to analyze the reasons for decreasing elasticity and strength, the results of similar testing under the conditions of Moscow, Florida, Arizona, and Vietnam have been used. It is shown that under the influence of radiation, destruction and cross-linking reactions occur that lead to the change in the elasticity of the studied materials.

The influence of silicone modifiers on the technological and operational characteristics of bitumen emulsions for waterproofing purposes is considered. The effectiveness of modifying anionic bitumen emulsions with silicone rubber destructors and bitumen binders obtained on their basis, which have a fairly wide range of ductility and increased elasticity, has been established.

The influence of n-methoxy- and N-(4-phenyl-aminophenyl)maleimides on the physical, mechanical and, operational properties of vulcanizates based on hydrogenated nitrile butadiene rubber (HNBR) Therban^® 3406 was studied. It was revealed that rubber containing N-(4-phenylaminophenyl)maleimide has the highest strength properties. Studies of thermal effects of aggressive environments have shown that vulcanizates containing maleimides are more resistant.

An article is devoted to the development of a diagnostic method for products made of composite materials using ultrajet technologies. The work carried out experimental studies aimed at obtaining data on the nature and depth of damage, depending on the presence of an embedded defect in a composite material’s layers. An analysis of results of ultrajet diagnostics is given, and informative criteria for assessing the quality of carbon fiber models are developed. At the end, conclusions are drawn about the characteristics of damaged surfaces of composite sample disks, and directions for further research and further development of this method for diagnosing composite materials are proposed.