Статті КТППтаПМ УДХТУ

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Application of Physical and Quantum-Chemical Characteristics of Epoxy-Containing Diluents for Wear-Resistant Epoxy Compositions
(MDPI, Basel, Switzerland, 2025) Kulikov, Andrii; Sukhyy, Kostyantyn M.; Yeromin, Oleksandr O.; Fedak, Marcel; Prokopenko, Olena M.; Sukha, Iryna V.; Poloz, Oleksii; Mikats, Oleh; Hrebik, Tomas; Kulikova, Olha; Lopusniak, Martin
ENG: Low-viscosity epoxy-containing diluents are used to reduce the initial viscosity of highly filled, wear-resistant epoxy systems and to improve filler wetting and dispersion. This study determined physical parameters by an atomic-increment approach and electronic descriptors using the Parametric Method 3 (PM3) semi-empirical method. Clear relationships were established between the effective molar cohesion energy and the solubility parameter with van der Waals volume. Linear dependencies were also obtained between the diluent surface tension and spreading coefficients on model high-hardness fillers, including silicon carbide, boron carbide, and normal corundum. The activity of epoxy diluents depends on the lowest unoccupied molecular orbital energy. These diluents influence processing and the final physical and mechanical properties of composites, making their selection critical for strength, hardness, and wear resistance. Computational analysis enables prediction of diluent behavior, reducing experimental time and cost. Integrating physical and quantum-chemical data into epoxy diluent design accelerates the search for optimal components and improves production of durable, high-performance epoxy composites.
Assessment of the Efficiency of Hot Helium Tank Pressurization Systems for Oxygen-Propelled Rocket Engines
(Publishing House “Akademperiodyka”, Kyiv, 2025) Sukhyi, Kostiantyn M.; Voit, S. M.; Mitikov, Yurii O.; Spirkin, S. V.; Sukha, Iryna V.
ENG: For the first time, a study of the design has been conducted, and a detailed weight summary of the hot helium pressurization system for an oxidizer tank of the first stage of a launch vehicle (LV) has been presented; the propulsion system of this LV uses boiling oxygen — RG-1 as propellants. The oxidizing generator gas was considered as the heat exchanger heat carrier. The weight of this system was also evaluated for an alternative common heat carrier — reduced generator gas. A good correlation was shown between the obtained results and known data from other pressurization systems. The efficiency of hot helium pressurization systems is demonstrated in the case of multiple reuses of the first stage of an LV. It is also reasonable to use it for the dual activation of the liquid rocket engine (LRE) of the second stage of an LV. In these cases, arising issues are solved using well-established, proven solutions. However, an analysis of technical literature shows that alternative solutions have not been thoroughly studied. In other cases, considering the high cost, structural complexity, actual low reliability, and lack of weight advantages, the use of hot helium pressurization systems (PS) is hardly justified. This primarily concerns LREs with afterburning of generator gas, where oxidizing gas is used as the coolant in the heat exchanger. It is also noted that it is necessary to provide helium reserves on board of the LV and to introduce a gas pressure regulation system in the tank. This is due to the large variations in pressurization path resistance and helium temperatures after the heat exchanger at the design stage. The result is an increase in the calculated gas pressure in the tank, leading to an additional weight increase of 5–8%. It is shown that helium reserves can be easily adjusted based on the results of the first flight tests, whereas reducing the thickness of the tank walls and the diameter of the hot pressurization pipelines with thermal compensators is extremely problematic.