Key Engineering Materials Vol. 899

Abstract: We have obtained polymer composites based on low-pressure polyethylene and carbon-containing fillers: carbon black, carbon nanotubes. The electrical properties of the obtained polymer composites have been investigated. Obtained polymer composites have electrically conductive properties. This article shows that the electrical properties significantly depend on the concentration, type of carbon-containing filler, as well as on temperature and voltage. It was found that containment of a certain amount of carbon-containing fillers leads to a formation of conductive paths composites, leading to the manifestation of a positive temperature coefficient in electrical resistance by the material.

Abstract: The present study deals with the investigation of catalytic cycloalkylation reactions of phenol with 1-methylcyclopentene. KU-23 and aluminum phenolate were used as catalysts for the process. The effect of kinetic parameters (temperature, duration, molar ratios of the initial components and the amount of catalyst) on the yield and selectivity of methylcyclopentyl phenols obtained as a result of scientific research was investigated. As a result, effective conditions were found for the production of para- and ortho-, ortho- (1-methylcyclopentyl) phenols with high yield and selectivity. It was determined that high yield of target product in the presence of phenol, 1-methylcyclopentene and catalyst KU-23, was 71.2% for phenol and selectivity for target product - 92.8% is obtained under the following conditions of cycloalkylation reaction: temperature 110°C, reaction time-5 hours, molar ratio phenol to methylcyclopentene-1 : 1, the amount of catalyst-10% according to the phenol taken. The cycloalkylation reaction of phenol with 1-methylcyclopentene in the presence of aluminum phenolate catalyst was carried out in an autoclave in a nitrogen environment and effective conditions were found: temperature 260°C, reaction time - 5 hours, molar ratio of phenol to 1-methylcyclopentene 1: 2, amount of catalyst 20% according to the phenol taken. Under these conditions, the yield of the target product is 44.3% for the phenol taken, and the selectivity is 87.6% for the target product. The chemical structures of the synthesized para- and ortho-, ortho- (1-methylcyclopentyl) phenols were confirmed by IR-, ¹H and NMR spectroscopy, and physicochemical parameters were determined.

Abstract: A curing system has been developed for obtaining high-strength compositions matrix, which is used in the production of composites based on reinforced carbon fiber using prepreg technology with a curing temperature of . A technology has been developed for combining an epoxy oligomer with a curing agent and modifier. The pot life of the prepared prepregs is at least 15 days.

Abstract: Thermal stability on air of polyurethane varnish coating prepared from diphenylolpropane, polyetherpolyol and polyisocyanate was assessed. The presence of urethane groups, formed by phenolic hydroxyl of diphenylolpropane, in the polymer structure was shown to decrease its thermooxidative degradation onset temperature. At the same time, deceleration of thermooxidative processes due to stabilizing effect of diphenylolpropane released at the beginning of thermal decay of polyurethane is observed in the higher temperature region.

Abstract: In this work, for the first time, salts of bivalent and trivalent metals were used as crosslinking agents for nanofiltration membranes based on sodium alginate. The developed membranes were investigated for chemical stability in protic and aprotic solvents, the dependence of the permeability of these solvents on their sorption into the membrane material was obtained. The separating properties of membranes based on sodium alginate crosslinked with metal cations were investigated. The retention coefficient of the model substance with a molecular weight of 626 g/mol, dissolved in ethanol, was 97%.

Abstract: The work presents the results of testing new eco-oils in elastomeric materials based on nitrile butadiene rubber (NBR). The influence of eco-oils grade and content on the rubber mixes based on NBR 2665 processing was studied. It is established that Phytonorman 212 acts as a technologically active additive that improves the rheological and relaxation characteristics of rubber mixes. Phytonorman 213 acts as an activator of the vulcanization process when eco-oils content is 2 phr. To maintain the complex of physical, mechanical and working performances, so as to prevent the slowdown of the vulcanization process at 7 phr eco-oil content it is recommended to adjust vulcanizing group component content and filler grade.

Abstract: Research has been carried out to assess the impact of mold fungi on polymer composite materials based on polypropylene produced by Omsk Polypropylene Plant LLC and unrefined natural rubber produced in Vietnam, grade RSS-1. The amount of natural rubber varied up to 15% of the mass. The fungal resistance of the compositions to the following types of fungi was assessed: Aspergillus niger, Aspergillus terreus, Aspergillus flavus, Chaetomium globosum, Paecilomyces variotii, Penicillium funiculosum, Penicillium chrysogenum, Trichoderma viredens. The decrease in the weight of the samples after incubation depends on the content of natural rubber in the composition. With the content of natural rubber in the composition in an amount of 1%, the average weight loss is 0.4% by weight, and when the content of natural rubber is 15% by weight. already ~ 2% of the mass. Starting with the addition of natural rubber in an amount of 1% by weight, the growth of fungi occurs, and the degree of their development is characterized by points 3-5. The resulting compositions are biodegradable, susceptible to the action of fungi, and, therefore, the manufacture of materials based on them will be an environmentally friendly alternative for further use.