Yakovenko O. Influence of external factors on the formation of physical properties of polymer-carbon nanocomposites

The thesis is devoted to the investigation of physical properties of the based on polymers composite materials (CM) with carbon fillers. The influence of interfacial interaction at the filler/matrix interface and features of the distribution of filler components in CM on their electrical, electrodynamic, thermal, magnetic properties have been determined. CM with aligned distribution of fillers which they acquired in the process of manufacturing under the action of electric or magnetic fields and CM with altered level of interfacial interactions due to the prior exposure of filler with ultraviolet light were investigated. In the process of research experimental set-ups for the implementation of techniques for manufacturing CM with modified physical properties have been developed. The influence of the fillers alignment and the level of interphase interaction of the CM components on the electrophysical and electrodynamic properties of the fabricated CM was experimentally determined in a wide range of filler concentrations (carbon component content - up to 10 wt.%) and electromagnetic radiation frequencies (up to 55 GHz). It is shown that in CM obtained under the influence of external fields there is anisotropy of structural, electrical and electrodynamic properties (electrical conductivity, dielectric permittivity, absorption and reflection efficiency of electromagnetic radiation). For CM with aligned filler distribution it is established that their concentration dependence of electrical conductivity is characterized by the presence of two thresholds of percolation: static and dynamic. In particular, it was found the influence of the carbon nanoparticles morphology on the peculiarities of formation of a percolation cluster in the epoxy matrix under the action of an electric field. It was found that the prior exposure of filler with ultraviolet light increases the heat and electrical conductivity of the CM, which is explained in the model of effective electric resistance by decrease of the contact electroresistance between the individual particles of the filler and increase of the number of conductive chains in CM. Within the Interphase Power Law model it has been shown that increase of the dielectric permittivity in CM, in which the irradiated with ultraviolet graphite nanoparticles were used as filler, is due to the increase of the ε of interphase layer.