The purpose of this work is to study the influence of the electric field strength of an electromagnetic wave with the maximum modifying effect on an epoxy basalt-filled oligomer, which is of great scientific and practical importance for the development of microwave oligomer modification technology. The optimal modes of microwave modification, under which the highest values of the mechanical properties of an epoxy basalt-filled polymer composite material are obtained, are identified: power of 400 W and an exposure time of 24 s. At the same time, the breaking stress in bending increases by 20%, the impact strength increases by 2 times, and hardness increases by 31%. A slight increase of 4.5% in heat resistance is noted compared to the composite obtained on the basis of an oligomer unmodified in the microwave electromagnetic field. The results of resistance to various aggressive environments are obtained, which show that the studied physical and mechanical characteristics of the epoxy basalt-filled material after exposure to an aggressive environment decrease by less than 14%, which corresponds to their good resistance to an aggressive environment. It is established that the effect of the microwave electromagnetic field on an epoxy basalt-filled oligomer is an effective modification method that improves physical and mechanical characteristics with a high level of temporal stability to climatic influences, with a coefficient of property retention of more than 90%.

This paper presents modeling data to select the optimal industrial unit for the microwave modification of an epoxy basalt-filled oligomer (EBO) at electric field strength E of an electromagnetic wave equal to 11.9 × 10³ V/m and a uniform distribution of the temperature field over the entire volume of the modified object. A mathematical description of the electrodynamic and thermal processes occurring in the object under consideration subjected to microwave exposure includes the Helmholtz equation for the electric field strength vector and the heat conduction equation. The joint solution of this problem in a three-dimensional formulation is based on the use of the finite element method, which in this work was implemented in the COMSOL Multiphysics^® 6.1 software environment. According to the modeling results, the use of microwave chambers with a traveling wave of a waveguide type is inefficient because the required value of the electric field strength E is not achieved, while the modeled microwave chamber with a traveling wave on a quasi-coaxial waveguide makes it possible to achieve the required value of the electric field strength E and uniform distribution of the temperature field over the entire volume of the modified object by reducing the generated power for the modification of an EBO from 400 W up to 300 W. Optimal parameters for modifying an epoxy basalt-filled oligomer in the microwave electromagnetic field in the working chamber with a traveling wave on a quasi-coaxial waveguide have been developed, which provide a uniform microwave modification of an EBO with a microwave installation capacity of 11.6 kg/h. A sketch of an industrial microwave working chamber has been developed, which provides a mode of the uniform modification of the oligomer at electric field strength E = 12.3 × 10³ V/m. The proposed microwave chamber with a traveling wave on a quasi-coaxial waveguide can be replicated for the microwave modification of filled oligomers of various chemical compositions.

Dispersed fillers (basalt, chromite) are modified in an induction installation at a power of 2 kW and a processing time of 60 s, which ensures a short-term high-temperature effect of high-frequency (HF) currents on the fillers and, as a result, improves the characteristics of the filled epoxy compounds based on them. The chemical composition of the fillers is found to change, which is associated with the removal of unbound moisture, an oxide film, and the oxides of the substances the decomposition temperature is lower than the modification temperature from the surface of basalt and chromite particles. Electron microscopy data demonstrate that basalt particles acquire a needle-like shape after exposure to HF currents, which positively affects the physicomechanical characteristics, since such a filler exerts a micro-reinforcement effect. Chromite particles weakly change their structure after HF current treatment. The study of the dielectric characteristics of the mineral fillers before and after HF current treatment shows that the dielectric constant increases significantly for basalt and chromite, indicating a change in their structure; this increases the strength characteristics from 7 to 17%.

A mathematical model of the solidification kinetics of an epoxy compound reflecting the effect of the technological modes of microwave treatment on its structure, physical and mechanical properties was developed. The equation of the crystalline phase growth for the case of microwave solidification of an epoxy compound, which allows the description of the mechanism of the non-thermal effect of the microwave electromagnetic field on the compound, was obtained

Basalt, known for its unique properties, is used for the production of yarns, fabrics, nets, and heat-insulating wool. Currently, a research is promoted on applicability of basalt as a dispersed filler for thermo- and rectoplastic materials without processing it into fibers. Therefore, investigation into interaction of epoxy binder with the crushed basalt is promising, which determines the aim of the given study. The objects of the research are the epoxy resin ED-20, polyethylene polyamine PEPA, and dispersed basalt filler. Spectrophotometer "Specord" with the IR-spectrum covering the area of 400 ÷ 4000 cm-1 was used to study the interaction of basalt filler with the epoxy oligomer and hardener. To take the photos of IR spectra of powders, the latter are pressed together with an excess of potassium bromide into tablets several millimeters thick. Special vacuum molds and pressure of several tons per 1 cm2 are used to produce the tablets. The ICS data confirm the interaction of ED-20 not only with PEPA, but also with the dispersed basalt. Amino groups, epoxy rings, CH groups of epoxy and aromatic rings of the binder and hardener undergo a reaction. As the content of the basalt filler in the epoxy increases, the same absorption maxima and bands are observed as in the IR spectra of the composite material with a low content of dispersed basalt. The difference is that the higher the basalt content in the epoxy matrix, the higher the relative intensity of such maxima, which indicates a stronger interaction of the components.

Power electronics devices are widespread in different engineering systems for housing and public utilities. But they have negative impacts to the power source. A typical example is using of the pumps operated by variable frequency drive in boiler stations and heating substations. The using helps both the energy savings and the voltage waveform distortion. If boiler station is supplied by emergency generator the voltage waveform distortion significantly increases. Voltage quality parameters are analyzed using a simulation model, built in MATLAB/Simulink, in different situations. The recommendations to ensure the specified voltage quality in the power supply system are created.