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Intensification of the formation process of sodium sulfate-modified biocomposite materials based on the glutinous matrix
(Kharkiv: Institute of Single Crystals of the National Academy of Sciences of Ukraine, 2023) Sadova, Oksana; Kashytskyi, Vitalii
The influence of the modifying additive (sodium sulfate) on the heat treatment regime of the biocomposition in the mold investigated in the article. The optimal content of sodium sulfate in the biocomposite material was determined. The influence of the content of the modifying additive on the compressive strength of biocomposites structured at different temperatures has studied. The optimal parameters of the thermal field temperature and the duration of heat treatment of the biocomposition for the given content of the additive, which provides the maximum values of mechanical characteristics, are determined. It established that the modifying additive with optimal content is able to increase the intensity of structuring of biopolymer binder. This consists in the rapid transition of the glutin binder from the gel state to the solid state with the formation of physicochemical bonds due to the removal of excess moisture under the influence of temperature. Fractograms of the fracture surface of biocomposites containing sodium sulfate analyzed.
Influence of Additives Processed by Physical Fields on Tribotechnical Properties of Polymer Composites
(2022) Sadova, Oksana; Kashytskyi, Vitalii; Melnychuk, Mykola
The influence of specific load on the intensity of weight and linear wear is determined in the article. The coefficient of friction and temperature in the zone of tribocontact of polymer composites, the components of which were processed in physical fields, were studied. The study of polymer composites with different content of components carried out at a constant sliding speed of 0.5 m/s. Epoxy resin and polyethylene polyamine hardener were used as a matrix to form polymer composites. To ensure increased heat resistance of the polymer matrix, a modifying additive (organosilicon varnish) was used. For the first time, the processing of organosilicon varnish in an electromagnetic field was applied, which allowed removing part of the solvent. Discrete aramid and glass fibers were used as reinforcing additives. For the first time, ultrasonic treatment of fibers in acetone was used, which allowed cleaning the surface of the fibers from contaminants and lubrications. Because of the use of the modifying additive and treated discrete fibers, the wear resistance of polymer composites increased by 30% due to the improvement of the adhesive interaction between the components of the system and the reduction of structural defects of the material. Removal of lubrication from the surface of the fibers and the solvent from the modifying additive increased by 0.1–0.15 the coefficient of friction of the polymer composites and will improve their service life. Friction polymer composite materials with high density and improved tribotechnical properties are designed for manufacturing brake systems of scooters.
Structuring of modified epoxy composite materials by infrared spectroscopy
(Єгипет: Університет Асьют, 2023) Sadova, Oksana; Kashytskyi, Vitalii; Melnychuk, Mykola
A comparative evaluation of the structuring processes of the epoxy polymer system with epoxy polymers modified with polyvinyl chloride solution and epoxy composites filled with finely dispersed titanium oxide powder was carried out. Analysis of the infrared (IR) absorption spectra of the studied epoxy polymer and epoxy composite materials showed the presence of deformation and valence vibrations of certain groups of atoms. The oscillations of groups of atoms with double bonds and regions of existence of triple bonds were also revealed. In the region of high frequencies, absorption bands correspond to valence vibrations of groups containing a hydrogen atom. The presence of triple bonds in the epoxy polymer system was determined, indicating unreacted functional groups. This fact corresponds to the low content of the gel fraction of unmodified epoxy polymers after heat treatment and indicates the formation of a system with insufficient chemical bonds. The absorption bands of the epoxy composite material filled with titanium oxide powder are characterized by a lower optical density and a larger peak area compared to the bands of the unmodified epoxy polymer, which indicates the formation of a higher number of crosslinking nodes of the epoxy composite material. The introduction of polyvinyl chloride into the composition of the epoxy polymer system increases the degree of structuring of epoxy polymers. However, a smaller number of formed chemical bonds of the modified epoxy polymer was recorded compared to epoxy composites containing titanium oxide particles. The highest degree of structuring is provided in polyvinyl chloride-modified epoxy composites containing titanium oxide powder due to intensive structuring and formation of double and triple bonds.

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