L. Yu. Matzui

Transport Properties of Composites with Carbon Nanotube‐Based Composites

Abstract The comparative investigation of structure, morphology, and transport properties of nanoscaled carbon materials (NCM) synthesized by different methods is carried out.

Structure–electrical resistivity relationship of N-doped multi-walled carbon nanotubes

Nitrogen-doped multi-walled carbon nanotubes (N-MWCNT) were synthesized by means of catalytic chemical vapor deposition technique using acetonitrile as carbon source material and ferrocene as catalyst. The structure of the synthesized N-MWCNT was characterized by means of microscopic (SEM, HRTEM) as well as spectroscopic (FTIR, Raman) techniques. Furthermore, the specific resistivity and the electrochemical properties of N-MWCNT were investigated and compared with those of pristine MWCNT. The results are discussed in terms of structural differences between pristine MWCNT and N-MWCNT.

The Effect of Filler Morphology and Distribution on Electrical and Shielding Properties of Graphite-Epoxy Composites

A comparative study of epoxy resin filled with thermoexfoliated graphite (TEG) of various dispersities has been carried out to investigate the effect of filler particles morphology on electromagnetic interference (EMI) shielding properties of composites within the 25.86–37.5 GHz frequency range of electromagnetic radiation. The shielding properties of a multilayered structure (LS) of TEG-epoxy presenting the set of alternating layers of TEG and epoxy have been investigated as well. The total content of TEG in this multilayered structure was 0.8 and 3 wt.%. It is found that the composites containing TEG exhibit enhancements in the electrical conductivity and the electromagnetic shielding efficiency as compared with those of composites with sonicated TEG.

Structure and magnetic properties of multi-walled carbon nanotubes modified with iron

Magnetic properties of multi-walled carbon nanotubes modified with iron MWCNT+Fe are studied in detail in the temperature range 4.2–300 K. Carbon encapsulated Fe nanoparticles were produced by chemical vapor deposition. Low-temperature SQUID magnetization measurements are supplemented by structural studies employing thermogravimetric TG analysis, transmission electron microscopy TEM , x-ray diffraction spectroscopy XRD , and scanning electron microscopy SEM . The magnetic susceptibility of MWCNT+Fe was also studied above room temperature to provide a complete picture of its magnetic phase transitions.

Resistance of a Nanocarbon Material Containing Nanotubes

The results of the experimental studies of resistivity of a nanocarbon material (NCM), which contains carbon nanotubes (CNT), and also the amorphous carbon particles and nanographite are presented. The main efforts were aimed at the ascertaining the mechanism of NCM conduction with regard to their phase composition.

Magnetoresistance of nanocarbon materials based on carbon nanotubes

The results of experimental investigations of magnetoresistance in nanocarbon material (NCM) containing carbon nanotubes in magnetic field up to 5 T and at temperature up to 0.54 K are reported. The obtained experimental magnetoresistance curves of NCM are described satisfactorily within the framework of the shrinkage effect of wave function of localized state in a magnetic field along with the spin-polarization mechanism.

Thermal characterization of expanded graphite and its composites

Using the guarded hot plate method, we have measured the thermal conductivity of compressed expanded graphite (EG) samples (densities from 0.4 to 1.95 g/cm3) along the compression direction (c axis) in the range 150–675 K and that of EG/epoxy composites (5–75 wt % EG) in the range 150–425 K. We also have measured the specific heat of EG samples at temperatures from 200 to 675 K. Their c-axis thermal diffusivity has been shown to decrease with increasing EG density. The thermal conductivity of the EG/epoxy composites and its variation with EG content are well represented by a rule of mixtures that takes into account the anisotropy in the thermal conductivity of the EG particles and their preferential alignment in the composites.

C–Co Nanocomposite Materials

The formation of cobalt particles on the surface of graphite supports via salt thermolysis is studied by x-ray diffraction, electron microscopy, Auger electron spectroscopy, and secondary ion mass spectrometry. The results demonstrate that each step in the fabrication of graphite–cobalt composites causes changes in the particle size, phase composition, and morphology of the deposit. The process involves the formation of a thin, fine-grained salt film on the surface of thermally expanded graphite particles as a result of impregnation; thermal decomposition of the salt, leading to the formation of crystalline cobalt oxide particles 50 to 100 nm in size, uniformly distributed over the surface of thermally expanded graphite; and the formation of Co particles on the graphite surface. The Co particles are 60–70 to 150 nm in size and form aggregates up to 400 nm in size.

Fluid Dynamics in Subnanometer Channels of Carbon Nanotubes

Abstract The surface tension and pressure of water in carbon nanotubes with diameters from 0.4 to 1.0 nm have been calculated and analysed in detail. In particular, it was shown that it is necessary to consider the Tolman correction during the calculation of these values.

Transport Properties of Epoxy-Binary Filler Composites

This paper presents the results of changes in electrical resistivity and thermal conductivity of polymer composites (CMs) with two-component filler. It is shown that thermal conductivity of epoxy CMs strongly depends on structural and morphological characteristics of carbon fillers. The synergistic effect in electrical and thermal conductivities of the studied CMs is observed upon addition of boron nitride BN. The presence of a sufficiently large number of BN particles in CMs promotes a more efficient formation of chains of carbon filler and reduces thermal (electrical) contact resistance between the filler particles by decreasing the distance between particles of the filler.