Polymer Science, Series D最新文献

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.

In the work, changes in the mechanical characteristics of a polymer composition based on polyester resin filled with encapsulated polylactide and nonencapsulated copper(I) oxide particles have been studied, as well as these particles dissolved by the resin components. It has been shown that encapsulated filler particles interact better with the matrix polymer than do nonencapsulated particles. This causes an increase in the ultimate strength and hardness of polymer composite material (PCMs), as well as a decrease in the magnitude of the ultimate deformation. A decrease in the strength characteristics of PCMs was noted in the case of partial dissolution of copper(I) oxide particles by components of the polyester resin. The reason for the change in strength characteristics is a decrease in the density of the polymer binder network due to the loss of styrene, as well as the formation of the complexes of copper salts.

The results of studies on the application of ultrasonic vibrations to parts under gluing are presented. Resulting from cavitation treatment of the glue, its properties are improved, its viscosity decreases and the penetrating ability exhibits an increase. Under the conditions of ultrasonic vibrations, owing to an increase in the surface wettability and the sound-assisted capillary effect, the actual area of gluing increases. Depending on the treatment mode and the surface microgeometry, the application of vibrations leads to an increase in the strength of the adhesive joint from 8 to 43%.

The paper presents the results of a study of the effect of treatment with nanosecond electromagnetic pulses (NEMPs) on some thermodynamic characteristics of polymers used in the production of reinforced fiberglass plastics. It has been found that NEMP treatment of YD-128 epoxy resin, Polysystem VE-3701 LVP vinyl ester resin, and Polysystem YMI-100 polyester resin has a modifying effect. It is noted that the treatment of thermosetting synthetic resins with NEMPs has a modifying effect, which is expressed in a change in viscosity, surface tension and polarity of the resins under study.

The paper considers technologies for the synthesis of amino-formaldehyde resins of KF-MT-NP and AFK-10 grades obtained using the peptization procedure, which could result in the complete elimination of vacuum drying and contribute to the ecologization of the process of synthetic resins production. A modifying additive, which is an inorganic polymer (IP) capable of efficient binding of free formaldehyde in the resin and stabilizing its properties by extending its viability to 6–7 months, is used as a peptizer.