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Polymeric construction materials based on epoxy resin, carbon fillers, such as graphene nanoplates (GNP), carbon nanotubes (CNT) and fillers of inorganic nature – perlite, vermiculite, sand with improved electrophysical characteristics have been developed. The electrophysical propertieгs of composites obtained in various ways which differ according to the principle of injecting components have been investigated. GNP were obtained in two ways. Size distribution of GNP obtained by electrochemical method is 50 to 150 nm. The average particle size is up to 100 nm. It occurs that these particles tend to aggregate as it is shown by the method of dynamic light scattering. The GNP obtained by dispersing thermally expanded graphite in water in a rotary homogenizer have a particle size distribution of 400 to 800 nm if very small particles and large aggregates are absent. The second method of obtaining GNP is less energy consuming and requires fewer manufacturing cycles, so it is more cost-effective. Obtaining composites using aqueous suspensions of GNP is environmentally friendly. Due to the hydrophobic properties of its surface the electrical conductivity of the system which uses vermiculite is higher than one of that which uses perlite for composites with CNT and GNP. It has been found that the difference of electrophysical characteristics between two systems which contain the same amount of carbon filler is caused by the nature of the surface of dielectric components – sand. By changing the content of dielectric ingredients can expand the functionality of composites if use them for shielding from electromagnetic fields. [ABSTRACT FROM AUTHOR]

The interaction of the epoxy component of fiberglass with the surface of a nanocarbon filler (multilayer carbon nanotubes) was investigated by experimental and quantum-chemical methods. It is shown that when the multilayer carbon nanotubes are introduced into the hardener of the epoxy composition to create fiberglass, the strength of this composite correlates with the degree of oxidation of the carbon atoms of their surface. Thus, the more oxygen-containing groups are on the surface of the nanocarbon filler, the smaller the strength of the eventual fiberglass is. To explain this effect, quantum-chemical calculations of the interaction of pure and oxidized surface models of a multilayer carbon nanotube (graphene-like planes) with a hardener molecule (triethylenetetramine) were performed by quantum chemistry methods. It is found that, regardless of the size of the graphene plane, the energy of the intermolecular interaction of triethylenetetramine with the model of the oxidized outer surface of multilayer carbon nanotubes is greater than the similar value for complexes with no oxidized outer surface. The oxidized surface of the multilayer carbon nanotube adsorbs the triethylenetetramine molecule exactly by amino groups, which are reactive centers when it is reacted with the outgoing resin. Thus, the oxidized multilayer carbon nanotubes impairs the interaction of the hardener with the epoxy. [ABSTRACT FROM AUTHOR]

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Metal-containing nanocomposites containing nanoparticles of organic and inorganic materials, attract considerable attention of specialists in recent years due to a large number of possible applications. NiCo nanoparticles have been obtained on the surface of unoxidized and oxidized multiwall carbon nanotubes (MWCNT) by chemical precipitation of the corresponding carbonates from a solution of hydrazine hydrate at a temperature of 350 K. Oxidation of MWCNT was carried out in a solution of potassium dichromate and sulfuric acid. The purpose of this work is to synthesize composites of MWCNT/NiCo and to find differences in their electrophysical properties dependent on the nature of the MWCNT surface. The transmission electron microscopic and radiographic studies showed the presence of phases composites with the size of crystallites of 20–30 nm. The packing density of agglomerates of metal particles is higher in composites with unoxidized MWCNT. The metal particles are arranged on the surface of MWCNT more evenly and in shape more close to spherical in composites with oxidized MWCNT. The method of thermogravimetric analysis shows that the process of composites oxidation during heating for a composite containing oxidized MWCNT is more intense. It indicates a smaller particle size of metals. The real and imaginary components of the complex dielectric and magnetic permeabilities of the disperse composites was determined by the methods of ultrahigh-frequency interferometry. The corresponding values are somewhat higher for composites containing oxidized MWCNT in the ultrahigh-frequency range. The values of imaginary magnetic permeability are higher by 18 % for unoxidized MWCNT composites at low frequencies. The electrical conductivity at low frequencies is 2.9 and 1.6 Ohm–1·cm–1 for composites containing unoxidized and oxidized MWCNTs, respectively. [ABSTRACT FROM AUTHOR]