Polymer Science, Series D最新文献

The potentialities have been studied of using a method for square plate torsion to determine the shear modulus in the plane of a sheet as a sensitive parameter for the aging of polymeric composite materials. The advantage of the method consists in the fact that one can perform the repeated measurements of mechanical parameters without destroying the sample. To substantiate the method, a cycle of drying and humidification of VPS-48 grade fiberglass plates and KMKU-3M, VKU-39, and VKU-45 grade carbon plastics has been performed after 7 years of full-scale holding in a moderately warm climate. The fact that the shear modulus in the sheet plane depends on the moisture content of materials in the course of their humidification and drying has been revealed. It has been proven that the method of square plate torsion can provide a high level of accuracy for measuring the value of this parameter.

An experimental setup and methodology for studying the triboelectric properties of materials at various temperatures are described. The technique is based on recording the electrostatic field that occurs during friction of surfaces of two materials forming a dynamic pair. The use of a tuning fork electrostatic field sensor that has been developed made it possible to carry out measurements in a wide temperature range from –50 to +60°C. Based on the experimental results, the dependences of charge accumulation and decay were obtained for various pairs of shoe materials (felt, leather, natural, and synthetic fabrics).

The production of wood composite materials and, in particular, plywood is one of the most effective ways to utilize waste in order to increase the recycling of by-products. The purpose of the work was to study the possibility of using steelmaking acidic slag as a modifying additive in urea–formaldehyde resins for plywood production and to determine the effect of steelmaking slag on the strength of plywood adhesive joints. The main sources of slag are the oxidation products of cast iron and scrap impurities (silicon, manganese, phosphorus, chromium, etc.), charge materials (lime, limestone, iron and manganese ore, scale, bauxite, fluorspar, etc.), and products of the destruction of refractory linings. As a result of the study, it has been found that the introduction of lignosulfonates, kaolin, and slags into urea–formaldehyde resin increases the reactivity of the finished glue. The ability of metal oxides in slag to bind hydroxyl groups has been proven; in this regard, when heated during pressing, the polymer does not break down into simple monomers, and the free formaldehyde of the urea–formaldehyde resin enters into a polycondensation reaction and is not evaporated from the glue.

The article presents the results of an experimental assessment of the adhesive strength of glass, carbon, and basalt plastics determined by the short beam and pull-out methods. It has been established that the adhesive strength values found by the short beam method depend very little on the chemical nature of a fiber, since the differences between them (using the same matrix and molding technology) do not exceed 5%. The adhesion strength values determined by the pull-out method for samples made with basalt fiber are 12.5% lower than for glass ones and 20% lower than for carbon ones. The article presents the results of statistical analysis, as well as the fracture energy values and the work spent on overcoming friction forces for all types of samples studied.

Modern trends focused on green technologies are driving the increasingly widespread use of biodegradable polymers in agriculture. The development of composite materials based on polylactide (PLA) is aimed at increasing the efficiency of using covering materials for growing plants in agriculture, as well as reducing the amount of polymeric wastes. In this work, mixtures of polylactide/polycaprolactone (PLA/PCL) and polylactide/natural rubber (PLA/NR) have been studied. It is established that, when about 10–15 wt % of PCL and NR are added to the PLA matrix, the structure changes and almost spherical domains are formed. In the course of studying the effect of UV radiation with a wavelength of 254 nm exerted on PLA/PCL and PLA/NR polymeric materials, it has been revealed that the presence of additives in the mixture already in an amount of 10 wt % promotes the inhibition of photolytic processes.

One of the trends in the creation of glazing materials, which are shock-resistant and shatterproof at fracture, is the application of multilayer composites. In this paper, the dependence of the shock resistance and other performance chrematistics of organic-glass-based triplexes on the technology of gluing under natural aging conditions and simultaneous mechanical loads is studied.

The article discusses the directions of development of adhesion promoters and compatibilizers for polymer–metal, polymer–fiber filler, polymer–disperse filler, and polymer–polymer systems, as well as modification of adhesives for gluing polymer materials. Among researchers, particular interest is directed towards the development of environmentally friendly promoters and compatibilizers.

The results of experimental studies on the modification of the properties of phenol–formaldehyde resin with alkyl aromatic hydrocarbons, which are contained in the light reflux of catalytic cracking, have been presented. The authors propose to use the resulting materials as part of organomineral compositions and film-forming compositions, since they have high strength and dielectric properties.

The properties of materials with a phase transition and their strengths and weaknesses have been considered in the paper, and the classification of materials with a phase transition according to the chemical composition of the core and shell of microcapsules according to the melting point has been analyzed. A classification of textiles has been presented depending on the input data, and the general characteristics of “smart” materials have been studied. Analysis of the methods for producing “smart” textiles and methods for studying the properties of textile materials with a phase transition have been carried out.

Currently, a broad spectrum of protective–decorative coatings are used to create paint-and-varnish materials. The formation of a protective–decorative coating on a wood surface occurs under the mandatory condition of adhesive interaction. This condition ensures wetting and the spread of a paint-and-varnish material over a substrate. In this paper, wetting estimation results are presented. Based on the found contact angles and surface tensions, the comparative parameters of the critical surface tension and adhesion work are determined by a computational graphic method.