| Abstract [eng] |
One of the goals of modern materials science is the development of composites with enhanced electrical conductivity accompanied by superior mechanical properties, but such requirements represent conflicting scenarios. Alternatively, the simultaneous usage of various nanofiller combinations may be a facile and promising strategy to effectively boost the electrical properties of composites. The combination of magnetic and carbon nanoparticles in a composite can provide multifunctionality properties: conductive, magnetic and ferromagnetic properties, as well as the electromagnetic shielding properties due to dielectric and magnetic losses. The first part of the dissertation is devoted to the investigation of the dielectric properties of several epoxy-based binary composite systems with magnetic inclusions in a wide frequency and temperature ranges. It was demonstrated that the percolation threshold of spherical particles in the polymer matrix can vary significantly due to the polymer-filler interaction difference. The second part of the dissertation is devoted to the investigation of dielectric properties of several ternary hybrid systems with a combination of magnetic nanoparticles and multi-walled carbon nanotubes (MWCNTs). It was found that when the MWCNTs are in a pre-percolation state, at certain small amounts of the magnetic component, a pronounced electrical properties synergy occurs due to the favorable formation of a co-supporting network by two types of nanofillers. The third part of the dissertation is devoted to advantages of using conductive lossy materials for microwave devices (absorbers and waveguide matched loads) miniaturization. Investigations experimentally and via simulations the microwave electromagnetic response of a pyramidal periodic structure based on a conductive lossy material were performed. |
