Key Engineering Materials Vol. 887

Abstract: The possibility of using the compositions of BaSO₄-KPO₃-Na₂B₄O₇ system as a glass-solder (frit) material was shown. A glass formation region has been established in BaSO₄-KPO₃-Na₂B₄O₇ system which is located in the borate-phosphate part of the concentration triangle and occupies ~41% of the triangle area. The concentration dependences of linear thermal expansion coefficient (TCLE), the softening temperature and the glass transition temperature was determined and discussed. It is established that the glass formation region, the concentration dependences of TCLE and technological temperatures values are significantly closer to those for CaSO₄-KPO₃-Na₂B₄O₇ system than for MgSO₄-KPO₃-Na₂B₄O₇ system. That may point out at the similar effect barium sulphate and calcium sulphate doping in the sulphate-phosphate-borate systems.

Abstract: The laser conoscopy method confirms the high optical uniformity of LiNbO₃:B crystals in the range of B₂O₃ concentrations from 0.008 to 1.24 mol. %. Minor signs of anomalous optical biaxiality appear in the conoscopic patterns of crystals at boron concentrations of 0.12 and 0.83 mol. % at a laser power of 90 mW. The maximum value of the angle of anomalous optical axes for the studied samples is 2V = 10 ́ for the sample (0.12 mol. %), аnd the value of anomalous birefringence corresponds to ∆n = 0.02·10^-5.

Abstract: The paper presents the research results on the production of doped composite materials by the method of out-of-furnace liquid-phase self-propagating high-temperature synthesis using oxides and mineral concentrates containing Zr and W as a charge. The positive experience of producing ingots of intermetallic alloys based on the Ni-Al system in one stage of the reduction process of joint metallothermy is shown. The use of Zr in the charge leads to grinding of microstructure of the ingots and the formation of intermetallic compounds containing Zr. The additional use of C, B₂O₃, and W in the charge results in the formation of complex borides and tungsten carbides in the ingots. Additional introduction of Cr₂O₃ into the charge is necessary for the formation of W carbides in the nickel aluminide matrix.

Abstract: The study of the deformation characteristics of thin polymer films has established 2 stages of increasing strain with increasing stress: the first stage in the elastic region is slow linear; the second stage is sharply exponential. The dependence of deformation (ε) on stress (σ) in polytetrafluoroethylene at various exposure doses has been experimentally investigated. Irradiation of the fluoroplastic films under study with electrons doses of 1, 3, 5, 7, and 10 kGy leads to significant changes in their mechanical properties, while the samples lose their plasticity and begin to break at a lower strain, which is associated with the formation of nanodefects in the structure of the material. A significant decrease in elongation is observed compared with unirradiated material. The reason for this is the degradation of the main chains of the fluoroplastic. With an increase in the absorbed dose, the Young's modulus increases exponentially, which is associated with a decrease in the distance between atoms in the structure of the sample. The resulting effect can be used in industry. The curves obtained for both non-irradiated and irradiated material are satisfactorily described in the exponential model.

Abstract: The main aims and the objectives of the study focused on solving current problems of nanomaterial science of new materials – creating the scientific basis for competitive methods of obtaining and controlling new composite materials having improved strength properties based on carbon-containing polymer matrices with nanotubes stabilized in them. A technology for obtaining experimental samples of nanocompositional polymer material based on polymethylmethacrylate, polybutylmethacrylate, and methacrylic acid doped with carbon nanotubes has been developed, using ultrasonic action and mechanical mixing of the composite mixture to achieve the most uniform distribution of nanotubes in the matrix. To determine the possibility of implementing the mechanism of adsorption interaction of the studied polymer material with the surface of carbon nanotubes, DFT calculations of the interaction of the polymer material component and single-layer carbon nanotubes of various types have been done.

Abstract: Over the past decades, significant advances have been made in the development and research of gas separation membranes based on ionic liquids (IL) and their polymer analogs (PIL) for membrane separation of "acid gases" such as CO₂ and H₂S from gas mixtures. Polymers containing various amino groups are of great interest for the selective separation of acid gases from gas mixtures, since ammonia and its derivatives are used in conventional purification. In this work, we have synthesized a monomeric ionic liquid based on 4 vinylbenzyl chloride with included triethylamine by the Menshutkin reaction. Further, on its basis, polymer ionic liquids were obtained by the method of free radical polymerization, then an anion exchange reaction was carried out to replace the Cl anion with Tf₂N. To analyze the process of thermal pyrolysis of poly [VBTEA-Tf₂N] a pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS) was employed in this research. The obtained materials, which are high molecular weight compounds, can be used to obtain polymer membranes of various architectures by traditional methods: both non-porous symmetric membranes and microporous asymmetric membranes.

Abstract: The interest in polymerizable ionic liquids of researchers is due to their unique properties, such as good thermal stability, low vapor pressure, and wide potential window of stability. The complex of these properties determines the prospect of using ionic liquids and polymers based on them in the technology of membrane separation. This article describes the synthesis of monomeric ionic liquids (IL) containing quaternary amino groups, pyridine, and imidazole groups based on vinyl benzyl chloride (conversion was 95%). Further, on their basis, polymer ionic liquids were obtained by the method of free radical polymerization with bulky anionic substituents. Proof of the formation of polimeric IL was carried out by NMR and FTIR spectroscopy methods. The molecular weight of the IL was determined by gel permeation chromatography and reached ~ 140,000. An anion exchange reaction was carried out to replace the Cl anion with Tf₂N.

Abstract: This paper studies deployable elements which are used in satellites and different terrestrial antenna devices. Many deployable elements are made from steel or thermoset polymer composite materials and have the following disadvantages like length limitation of deployable elements, labour intensity of manufacturing process of deployable elements etc. For this purpose a deployable tube boom element was chosen and a forming method for manufacturing deployable tube element from thermoplastic polymer composite material was developed.

Abstract: This paper presents the findings of experimental studies of the physical and mechanical properties of wood-filled composites based on polylactide (PLA) and vegetable filler in the form of wood flour (WF) thermally modified at 200-240 °C. It also reveals the dependence of the tensile strength, impact strength, bending elastic modulus, and density of composites on the amount of wood filler and the temperature of its thermal pre-modification. We established that an increase in the concentration of the introduced filler and the degree of its heat treatment results in a decrease of the tensile strength, impact strength and density of composite materials, while with a lower binder content, thermal modification at 200 °C has a positive effect on bending elastic modulus. We also found that 40 % content of a wood filler heated to 200 °C is sufficient to maintain relatively high physical and mechanical properties of composite materials. With a higher content of a wood filler, the cost can be reduced but the quality of products made of this material may significantly deteriorate. However, depending on the application and the life cycle of this product, it is possible to develop a formulation that includes a high concentration of filler.

Abstract: The paper presents the results of the study of registered acoustic emission (AE) parameters during static deformation and damaging of polymer composite materials (PCM). Mechanical tests were done by a static tension and a static three-point bend, accompanied by an acoustic emission method. The assessment of the loading rate effect on defects formation processes was done by additional static tension test at rate equal half of recommended by the standard and static three-point bend test at rate ten times lower than that calculated by the standard. Clustering by frequency components of the recorded AE signals with a self-organizing Kohonen map was performed. The characteristics of the types of PCM structure damage by the centroids of the obtained clusters are given. Based on the clusters accumulation during mechanical tests, the stages of damage formation for static tension and static three-point bend, the loading rate effect on the process of damage formation are described.