The rheological properties of epoxy binders based on various hardeners and additives have been studied. The binder based on ED-20 epoxy resin and Etal-23X hardener, and the binder based on Epilox epoxy resin (Component A) and Epilox hardener (Component B) are recommended to be processed at temperatures from 25 to 40°C. The EDI binder with the addition of TCEP fire retardant has low viscosity and high pot life at temperatures from 40 to 60°C; the addition of Etal-1 diluent increases its pot life. The chemical resistance of glass- and basalt-reinforced plastics, manufactured in the form of rings based on various binders and reinforcing fillers, has been determined in various chemical media, such as 10
Diverse applications of a cathodic disbondment method are examined, from the first experiments in cathodic protection of metal structures to modern approaches to enhance adhesive interaction at the coating-metal interface. Various polymer composites are used for these purposes from the mid-twentieth century to the present day (epoxy, polyurethane, bitumen-polymer, plastisols, and some any other special coatings). Scientific literature on each polymer type is analyzed, and the main avenues for finding coatings that offer high resistance to cathodic polarization are outlined.
Ultrasonic liquid processing allows for the intensification of technological processes based on the use of dispersed systems.Despite certain advances in individual systems, there are currently no studies aimed at establishing the relationship between the liquid medium and the dispersed phase properties and the ultrasonic processing parameters that determine cavitation-erosion activity and the intensity of acoustic flows. This study was conducted on model dispersed systems with varying viscosities and is divided into two parts. The first examines the effect of liquid viscosity on the propagation of cavitation region and its erosive activity. The second examines the change in cavitation-erosion activity upon the addition of a dispersed phase to the liquid.
A new copolymer based on benzocyclobutene-4-yl vinyldimethylsilane has been developed and synthesized for application in the manufacture of printed circuit boards. The influence of the copolymer composition on the viscosity of its solutions in mesitylene has been established, and concentration dependences of viscosity have been obtained. The possibility of using solutions of the benzocyclobutene-4-yl vinyldimethylsilane copolymer as a binder for producing prepregs for the manufacture of fiberglass laminates has been demonstrated. The dielectric properties of the obtained fiberglass laminate allow recommending it for use in the production technologies of microwave printed circuit boards.
A production technology of a modified colorless phenol formaldehyde resin of the SF-BP brand which will find application in the production of paper–resin films intended for finishing of wood board materials as well as in the fabrication of laminated paper plastics is presented. The properties of the synthesized resin are studied. Process parameters of the production process of paper–resin films with the use of the modified resin are developed as well as the assessment of the quality of these films is performed. The modes of hot lamination of a wood board material by way of example of plywood as well as modes of pressing of laminated paper plastic are developed. The results of determination of the physical and mechanical properties of the obtained composites are presented.
This article presents a comparative analysis of two methods for determining the adhesion strength between an epoxy matrix and carbon fiber: pull-out and an improved knot-pulling method. The study identified the main advantages and disadvantages of each method. The consistency of test results obtained using the pull-out and knot-pulling methods was established. Results of optical microscopy studies of the adhesive contact zone are presented.
The effect of the nature and structure of polyols in the composition of an aqueous polyurethane dispersion on the properties of low-temperature heat-activated adhesive compositions obtained based on them is shown. The correlation between the structure of the polyurethane polymer and temperature of activation, strength characteristics, and heat resistance of the adhesive for membrane vacuum pressing is determined. Dependences of phase transitions for polyurethanes with different compositions are presented.
This paper summarizes literature data on the use of native sawdust from deciduous and coniferous trees as oil sorbents for removing hydrocarbons from water surfaces during emergency spills. Data on the maximum oil sorption capacity of sawdust from various tree species are highlighted. Comparative characteristics of the sorption capacity of sawdust for petroleum products are addressed in comparison with other cellulose-containing sorption materials and industrial oil sorbents.
This review summarizes published data on the use of modified sawdust from deciduous and coniferous trees as oil sorbents for removing hydrocarbons from water surfaces during emergency spills. The main modification methods and their impact on sorption characteristics for oil and petroleum products, as well as water absorption, are described. Data are highlighted on the maximum oil sorption capacity of modified sawdust from various tree species, as well as the efficiency of removing oil and petroleum products from water surfaces.
A computerized quality management system was developed for analytical monitoring of import-substituting pharmacopoeial assortment of chemical reagents and highly pure substances. The product range produced by one of the main Russian manufacturers, EKOS-1, and leading foreign companies was analyzed. The elements of the system are considered according to the limiting quality indicators. Promising analytical methods and instruments were identified for each indicator.
Currently, the recycling of polymers and polymer products is, to a certain extent, hampered by a number of technical barriers, including contamination of feedstock, lack of stability and coordination in the supply chain, inefficient sorting, weak technological capabilities, and the absence of end markets. On the other hand, the focus on sustainable development in the field of ecology is stimulating interest in recycled polymers, whose use is seen as a solution to environmental problems. This study demonstrates that adding recycled polyethylene and biodegradable polymers, such as polylactide and polycaprolactone, to a low-density polyethylene matrix changes the morphology and properties of the blend, which makes it possible to improve the biodegradability of the material. It is shown that the presence of polycaprolactone and recycled polyethylene in the blend contributes to accelerated degradation of samples after 120 days of incubation in soil, with the appearance of biofouling and surface degradation observed. In a blend with polylactide, this effect is less pronounced, but a general change in properties and a decrease in weight are still present. In the blend containing polylactide, turbidity is detected, indicating hydrolytic processes.
This paper summarizes data from domestic and international sources on the utilization of chemical water treatment (CWT) sludge, generated during the softening of water for boilers at combined heat and power plants and petrochemical plants, as part of a binders. Composition of CWT sludge is presented from various literary sources. The main uses of CWT sludge in various sectors of national economy are briefly outlined. Information is provided on the potential use of various natural mineral compounds and industrial waste as fillers in gypsum binders. It is shown that the introduction of CWT sludge into gypsum binders contributes to changes in water absorption and setting time, as well as positively impacts flexural and compressive strength, and other physical and mechanical properties. Data is provided on the use of organic and inorganic plasticizers in gypsum binders.
This article presents the results of a study of the microstructure of carbon and glass fillers, as well as carbon- and fiberglass-based composites using the adhesive binder VS-14-6. Based on the research results and microstructural analysis, it was concluded that the binder has high penetrating ability due to its low viscosity. Cohesive or adhesive failure of polymer composite materials (PCMs) along the fiber—matrix interface with various fillers was identified. It was established that PCMs with cohesive failure along the fiber—matrix interface exhibit high mechanical properties in tensile and compressive tests.
In this paper, the specific features in the machining (cutting) of parts from polymer composite materials were considered. The materials for the cutting part of tools and their geometric parameters were selected, and technological regimes were recommended, considering the properties of polymer composite materials that characterize their machinability. The differences between the machining of polymer composite parts and the processing of metal products were revealed.
Two key factors influencing the surface quality and strength characteristics of epoxy-matrix carbon fiber-reinforced plastics during milling, namely, feed rate (from 100 to 400 mm/min) and spindle speed (from 5000 to 20000 rpm) were studied. The results of temperature measurements in the cutting zone under the studied conditions were presented. Criteria that qualitatively characterize the mechanical and thermal stresses during milling and provide the explanation and prediction of changes in the strength properties of carbon fiber-reinforced composites were proposed. Optimal regimes minimizing the negative impact on the material and preserving its strength properties were determined. It was shown that the best results are achieved with a combination of moderate feed rates and spindle speeds.
The properties of unidirectional basalt-fiber reinforced polymer (BFRP) and glass-fiber reinforced polymer (GFRP) rebar for construction purposes, produced by pultrusion and die drawing methods, have been studied using longitudinal bending, dynamic mechanical analysis, and thermomechanical analysis. It is shown that the pultrusion technology does not ensure complete curing of the epoxy matrix. A significant reduction in the heat resistance and a change in the coefficient of linear thermal expansion of the rebar in the glassy and rubbery states of the binder in pultruded rods have been revealed.
The methods to produce adhesives of moisture resistance classes D3 and D4 based on polyvinyl acetate dispersions stabilized with polyvinyl alcohols and widely used for gluing wood, wooden products, and furniture are systematically reviewed. The techniques to increase moisture resistance of adhesives based on polyvinyl acetate dispersions by the addition of reactive components (modifiers) to the finished adhesive dispersion and functional monomers or oligomers to a reaction mixture are described.
The influence of electrical insulation system materials on its resistance in aqueous and water–salt environments has been studied. It has been established that the use of wires with high-temperature enamel insulation in electrical devices operating in aqueous and/or water–salt environments does not provide the required level of water resistance for the insulation system. Data on the resistance of insulation systems when operating in salt water are presented.
Effect of ethylene propylene diene monome S 505A and nitrile butadiene SKN 2645 rubbers on the rheometric properties of rubber compound, as well as the rubber’ physico-mechanical and performance characteristics, was studied. It was found that rubber containing a combination of S 505A and SKN 2645 rubbers in a 25 : 75 weight ratio exhibits superior rheometric properties, and its vulcanizate exhibits high physicomechanical properties. This rubber is resistant to hydrocarbon and acid–base environments and can be recommended for the manufacture of sealing and sealing gaskets in the automotive industry.
The paper presents the results of a kinetic study of curing ED-20 epoxy resin with the TETA amine hardener, modified with laproxides of varying structure, functionality, and viscosity, using the dielectric permittivity method. It is shown that the curing process depends substantially on the content and nature of laproxide. The values of ε were obtained for the initial stage and kinetic region of the polycondensation reaction of epoxy oligomers with laproxides, as well as after their complete curing.
