Polymer Science, Series D最新文献

The effect of an increase in the adhesion strength of steel–rubber adhesive joints based on ethyl 2‑cyanoacrylate and polymer para-dinitrosobenzene is found and studied. The increase in the adhesion strength of adhesive joints based on ethyl 2-cyanoacrylate and polymer para-dinitrosobenzene with rubber and metals can be associated with the formation of an azomethine group and additional intermolecular interactions.

Polymer materials were created on the basis of an unsaturated polyketone, and their mechanical and sorption characteristics were determined.

Polybutylene terephthalate samples stabilized with various chain antioxidants were obtained, and their basic physical–mechanical properties were studied. It was found that the antioxidants used significantly increase the initial physical and mechanical properties of polybutylene terephthalate. The reason for the change in the original polymer basic properties has been established: the plasticizing effect of antioxidants.

The preparation of biodegradable composite materials based on polyvinyl alcohol, starch, and cellulose is described. The resulting bioplastics are as promising reinforcing polymer systems of cellulose-containing materials that used for the production of packaging materials of various purposes. It was shown that starch and cellulose inclusions make it possible to regulate the physical and mechanical properties of composites and to obtain rapidly degradable naturelike materials in environmental protection conditions.

Studies address determination of the strength and water resistance of glue joints based on poly(vinyl acetate) dispersions according to EN 204 and EN 205 European Standard methods. These standards govern the test procedure and the required values when determining wood shear strength along its fibers. The strength and water resistance of the glue joints are determined using adhesives based on poly(vinyl acetate) dispersions of various brands. The quality of adhesive materials applied in the woodworking industry in Russia is analyzed, and recommendations for their further use are proposed. In the joinery-construction production, the D3 adhesives should be applied. The glue joints based on these adhesives may be used indoors under various temperature–humidity conditions. As a result of tests, the strength and water resistance of the glue joints formed by various brand adhesives are determined. It is shown that only four adhesive brands comply with the DIN EN 204–2003 D3 standard. Mobex 3335 adhesive, K-1 adhesive dispersion, and Kestokol D30 and Polidis PVA adhesives meet the DIN EN 204–2003 D3 standard in the average strength and water resistance. The Kestokol D300 adhesive shows the maximum strength and water resistance.

The role of the scale factor has been studied when testing the strength of the adhesive joint of heteroaramid fibers using the method of tearing out the tow from the adhesion cell formed by a loop pulled into a knot. It has been established that the shear strength of the joint decreases by half with an increase in the gluing area by two orders of magnitude—from 0.1 to 10 mm². The value of the strength of the adhesive joint of cyanoacrylate adhesive with the studied fibers determined by the “loop” method turned out to be close to the values of shear adhesive strength for epoxy binders and organoplastics.

One of the directions for improving the production of adhesive materials is the modification of phenol formaldehyde resins. Utilizing the waste and intermediate products from wood-processing industries, particularly in the form of wood-pyrolysis liquid, will deepen the process of comprehensive resource utilization. A body of research lays the groundwork for further developments and targeted regulation of the physicochemical properties of wood-pyrolysis liquid-modified phenol formaldehyde adhesive. The experimental results clearly show that the addition of wood-pyrolysis liquid in various fractional phases (up to 15–20%) significantly increases the delamination and bending strength of birch plywood samples beyond the standard. This is due to the resinous and fatty acids in the wood-pyrolysis liquid reacting with formaldehyde. The resinous and fatty acids integrate into the polymer molecule of the phenol formaldehyde resin, forming a spatially branched structure, leading to the formation of a polymer with a new set of properties. In the interaction mechanism of wood-pyrolysis-liquid-modified phenol formaldehyde adhesive, there is a sequential increase in the molecular weight of substances and, consequently, the depth of penetration.

The DSC method revealed endothermic effects (–613.9 J/g) during gypsum dihydrate heating associated with the heat absorption during the release of crystalline hydrate water in the range of 100–250°C during the heating process. Mass losses during water evaporation were determined by TGA and amount of up to 20%. The thermal conductivity coefficient of gypsum samples is 0.288 W/m K. The influence of mineral additives—glass spheres, wollastonite, and chopped basalt fiber—on changes in the properties of gypsum samples at curing times of 2 h and 1, 3, 7, and 14 days was studied. An addition of glass spheres up to 10 wt % reduces gypsum strength by 10–13% and density, by 16%, additive up to 20 wt % reduces strength by two times and density by 36–40%, and additive up to 50 wt % reduces strength by from five to six times and density by 80–85%, with the thermal conductivity coefficient decreasing to 0.236 W/m K. An addition of wollastonite 10–20 wt % increases the strength of gypsum samples by 13–16%, and addition of 50 wt % reduces the strength by two times. An addition of 0.5–1.5 wt % chopped basalt fibers increases strength by 10–16%, as well as the strength gain rate. Additions of wollastonite and basalt fibers practically do not change the density of gypsum samples, but increase the thermal conductivity coefficient to 0.320–0.373 W/m K.

This study investigates the effect of introducing aluminosilicate microspheres treated with low-temperature plasma on the properties of elastomeric fire- and heat-protection materials. The rheometric characteristics of the rubbers and the physical and mechanical indicators of the vulcanizates based on SKEPT-40 and their resistance to high-temperature exposures were determined. The impact of the content of modified microspheres on the comprehensive vulcanization, physicomechanical, and fire- and heat-protection properties of rubbers based on ethylene propylene diene monomer was established.

The paper is devoted to the development of a new phosphorus–nitrogen-containing fire retardant with multifunctional action, which is a product of the interaction of dimethylphosphite and dicyandiamide (DDP). The resulting product has a close-to-optimal ratio of nitrogen and phosphorus atoms, which determines its adhesive, thermal stabilizing, and antipyretic activity. DDP has a positive effect on the fire- and heat-protective properties of the material: the time for heating the unheated surface of the sample to 100°C increases by 39–57%, and the linear burning rate decreases by 17–21%. It has been shown that the strength of the adhesive joint increases by an average of 30–70% and the composition containing DDP exhibits consistently better adhesive strength than the original adhesive composition up to 80°C.