Key Engineering Materials Vol. 887

Abstract: The work is devoted to the study of the effect of marine calcium carbonate on the polymer matrix. The composite flat strips based on low-density polyethylene filled by crushed shells of sea oysters, which are the main source of sea calcium, were investigated. Marine calcium carbonate masterbatch was used to reduce the cost and stiffen the resulting composite materials. The effect of the masterbatch concentration on mechanical properties and oxidative degradation were studied. The materials were exposed to three climatic factors (temperature, UV-radiation and moisture). The addition of crushed shells led to embrittlement of the test materials. According to FTIR analysis, the absorption band at 1432 cm^-1 attributed to carbonate minerals decreased or completely disappeared after weathering test due to washing out of CaCO₃ from the composite.

Abstract: This article presents the results of studies of obtaining wood composite board materials without binders using the method of preliminary steam explosive treatment, as well as an assessment of the impact of impregnation conditions and continuous steam explosive activation of wood on the physical and operational properties of wood-based composite materials based on activated fibers. The rational operating parameters for obtaining board wood-composite materials (WCM) have been determined. We established the influence of impregnation modes (temperature, catalyst concentration), continuous steam explosive treatment with afterwash (temperature, pressure, intensity of mechanical action), as well as the properties of activated lignocellulose fibers (composition and morphological structure) on the operational properties of WCM. The expediency of introducing a catalyst (sodium bisulfite) at the washing stage has been proved, since the introduction of sodium bisulfite during impregnation before steam explosive treatment promotes the formation of lignosulfonates in the activated material, which participate in the formation of the physical properties of WCM.

Abstract: The purpose of the work is to develop new polymer composite nanomodified materials for the restoration of hull parts of agricultural machinery.As a result of research, a comparative analysis of the properties of composites based on epoxy resin ED-20 with the addition of 0.1-1.5 mass parts of carbon nanotubes “Taunit-M” obtained by free casting and direct pressing was carried out. The effectiveness of the developed compositions is proved when using them as binders in the production of fiber-reinforced composites.It was found that the introduction of 0.5 to 1 mass. parts CNT "Taunit" allows you to increase the strength characteristics of the resin ED-20 1.5-4 times with uniaxial tension, 2-2.5 times with three-point bending and reduce weight wear by 5-10 times.

Abstract: The paper studies issues related to physicochemical and chemical techniques for the modification of wood-polymer composites with a thermoplastic polymer matrix (WPCs) to improve their physical and mechanical properties. The physicochemical modification was performed by photochemical crosslinking with the exposure of WPC specimens to UV irradiation. Chemical modification was performed by introducing benzoyl peroxide into the material composition, leading to chemical crosslinking of polyethylene macromolecules of the WPC polymer matrix. As a result of the study, quantitative characteristics of the effect of the benzoyl peroxide content in the composite, as well as the WPC specimen UV irradiation intensity and duration on the basic physical and mechanical properties of the material have been obtained. The efficiency of physicochemical techniques for modifying WPCs has been estimated by changing the specimen properties such as Brinell hardness, water absorption, and impact strength. It has been found that the Brinell hardness increases by 80 % as compared to unmodified WPC specimens. Effective modification of wood-polymer composites with polymer matrices based on high-density polyethylene may lead to a significant improvement in the quality of products made of these materials.

Abstract: Carbon nanotubes have been studied by scanning electron microscopy. Measurement modes - accelerating voltage 10 kV, current in microscopy mode 10^-9 A. The sample was applied to a metal mesh. Spectroscopic data indicate that this sample consists of carbon (peak at 280 eV). There are no other intense peaks in the spectrum; no impurities were detected by this method. Determination of physical and mechanical characteristics was carried out on a testing machine model N5K-S.

Abstract: The main goal of the work is to identify the advantages of fast reactors when using nanotechnology in the manufacture of core materials. The research methods are based on the adaptation of known technologies (including powder metallurgy) to the design of fast reactors and on the numerical simulation of physical processes carried out using computer programs for the analysis of emergency conditions of fast reactors (including anticipated transient without scram - ATWS). The results of the research show that the use of structural materials based on steels hardened by nanooxides in combination with fundamentally new types of fuel based on composite materials can significantly improve the safety of nuclear technics. Sintered mixtures of ceramic microgranules (oxide, nitride) and nanoadditives of metallic beryllium or uranium are considered as nuclear fuel. Such composite nuclear fuel improves reactor safety and power. The following types of composite fuel were analyzed: mixed oxide with additives of a beryllium or uranium nanopowder, mixed mononitride with additives of a beryllium or uranium nanopowder. Most preferably, a ceramic-metal pellet fuel based on mononitride microgranules and uranium metal nanopowder. The use of such fuel (with a volume fraction of metallic uranium up to 20%) significantly increases the safety of the reactor, combining the advantages of metal and ceramics and completely neutralizing their disadvantages. The proposed materials are of practical importance in the development of new concepts of nuclear technics, in the transition to large-scale nuclear power and high-power reactors. The use of a new cermet-based composite fuel increases the power of the reactor and significantly increases the safety of the reactor.

Abstract: The electrochemical behavior of 8-oxyquinoline and chelate complexes based on it (Sn (Oxin)Cl₃, Ge (Oxin)Cl₃, Ti (Oxin)Cl_3, W(Oxin)₂Cl₄, Fe (Oxin)Br, Sb (Oxin)Cl₂, Sb (Oxin)Cl₄, Sn (Oxin)₂Cl₂, Ti (Oxin)₂Cl₂ have been studied by cyclic voltammetry in aprotic solvents in a three-electrode system on platinum and glass-graphite disk electrodes. It has been shown that in the case of metal oxyquinolinates, the ligand is 8-oxyquinoline reducing in two one-electron diffusion waves. The first wave is observed at less negative potentials than the first quinoline one, while the second waves have almost the same potentials. The first wave is related to the OH^- proton discharge. The complexes under study are electrolytically oxidizable. A single two-electron peak is observed in the cyclic voltammogram in the anodic region for the Ti (Oxin)Cl₃ chelate complex. This is probably associated with two irreversible sequential or parallel stages with close oxidation potentials. By analogy to the processes considered for 8-oxyquinoline, the rupture of the oxygen-metal bond is observed at the first stage. The resulting radical cation is unstable and decomposes into a radical and a cation with a positive charge in the titanium atom. Electrolytic oxidation of complexes Fe (Oxin)Br, Sb (Oxin)Cl₂, Sb (Oxin)Cl₄, and Sn (Oxin)₂Cl₂ is similar to that of Ti (Oxin)Cl₃.

Abstract: Waelz oxide is a secondary zinc raw material and a product of Electric Arc Furnaces (EAF) dust, copper smelters dust and zinc production residues. The use of Waelz oxide in the traditional RLE (Roasting-Leaching-Electrowinning) zinc production scheme requires the removal of halogens (fluorides and chlorides). Waelz oxide is mainly composed of zinc oxide, also contains zinc chloride. Zinc chloride is removed into the gas phase at heating. Microwave heating is one of the promising methods. Test experiments of microwave heating of a ZnO-ZnCl₂ mixture were carried out. It was shown that zinc chloride absorbs microwave radiation; zinc oxide does not absorb microwave radiation. The degree of zinc chloride removal from ZnO-ZnCl₂ mixture was 100%.

Abstract: The paper considers the technology of obtaining metal nanoparticles by the method of induction levitation. A bulk metal sample of titanium with a purity of 99.9% and a mass of 0.4 g, which was heated and held in a state of flux levitation by a high-frequency electromagnetic field, was used as the basic raw material for nanoparticles. The obtained nanoparticles were examined using Х-ray diffraction analysis to determine the purity of the product. The analysis showed that it is high. Particle size distribution was investigated using dynamic light scattering, where the average particle diameter is 55 and 47 nm, obtained in Ar and He, respectively. The morphology was studied using scanning electron microscopy, according to which the average diameter of the particles synthesized with He and Ar is 45 and 57 nm, respectively.

Abstract: The formation of polymeric acetylacetonates of magnesium, aluminum, iron, zirconium, and vanadyl under conditions of mechanochemical activation with subsequent condensation in boiling toluene has been investigated. The obtained compounds have been studied by the methods of gel chromatography, X-ray diffractometry, and positron annihilation and IR spectroscopy. Aluminum chelates have been studied by means of NMR spectroscopy. It has been demonstrated that the mechanochemical activation with subsequent boiling in toluene results in the formation of polymeric chelates, mostly those of iron, zirconium and, to a smaller degree, chelates of aluminum, magnesium, and vanadyl. The molecular weight of soluble high-molecular fractions is in the range 3000–5000 Da. The layered polymer structure has been revealed. Cross-section areas of polymer chains and volumes of coherent scattering regions have been calculated from the diffractometry data. The morphology of polymers consisting of spherical particles of sizes in the range 100–700 nm has been investigated. Based on the data of positron annihilation spectroscopy (PAS), density, and nitrogen low-temperature adsorption, the dependence of the chelate stability on the specific polarizing potential has been determined. A fractal structure of solid-state polychelates has been revealed.