O. B. Anikeeva

Structural and Physical Properties of MWNT/Polyolefine Composites

Composite materials containing multi-walled carbon nanotubes (MWNT) in polyolefine (polyethylene and polypropylene) matrix were prepared by coagulation precipitation. The morphology and structure of produced composites was investigated by scanning and transmission electron microscopy. Thermal analysis (oxidation in air) was performed for composites in temperature range 20–500°C. It was shown that the addition of MWNT increases the thermal stability of composites. Electrophysical properties of MWNT/PSt composites were investigated using a four-probe technique. Observed electrical percolation threshold of composite materials is near to 3–3.5wt%. Electromagnetic (EM) response of prepared materials was investigated in broadband region (26–37 GHz and 250–500 GHz). It was found that the EM response of MWNT/polyolefine depends on their electrophysical properties with percolation threshold near 2–3wt%.

Electrophysical and Electromagnetic Properties of Pure MWNTs and MWNT/PMMA Composite Materials Depending on Their Structure

Three types of carbon multi-walled nanotubes (MWNT) with different morphology and mean diameter (7.5, 10.5, 22 nm) were used to produce polymethylmetacrylate-based composites (MWNT/PMMA) with variable MWNT loading (0.5–5wt%). The electrophysical properties of produced composites and electromagnetic response in frequency range of 2–12 GHz were investigated. Electrical conductivity of composites depends on the MWNT type increasing with lowering of the nanotube diameter and loading in composite. Reflectance and transmittance coefficients were calculated from dielectric permittivity data and found to correlate with electrical conductivity. The highest level of EM reflection was obtained for 7.5 nm MWNT-based composites and makes the value of 0.65–0.7, whereas 22 nm MWNT/PMMA composites are more transparent for EM radiation with reflection coefficient 0.3–0.4 for the highest MWNT loading. Thus MWNT/PMMA composites demonstrate high EM shielding properties.

Structure and Properties of Multiwall Carbon Nanotubes/Polystyrene Composites Prepared via Coagulation Precipitation Technique

Coagulation technique was applied for preparation of multiwall carbon nanotube- (MWNT-)containing polystyrene (PSt) composite materials with different MWNT loading (0.5–10 wt.%). Scanning and transmission electron microscopies were used for investigation of the morphology and structure of produced composites. It was shown that synthesis of MWNT/PSt composites using coagulation technique allows one to obtain high dispersion degree of MWNT in the polymer matrix. According to microscopy data, composite powder consists of the polystyrene matrix forming spherical particles with diameter ca. 100–200 nm, and the surface of MWNT is strongly wetted by the polymer forming thin layer with 5–10 nm thickness. Electrical conductivity of MWNT/PSt composites was investigated using a four-probe technique. Observed electrical percolation threshold of composite materials is near to 10 wt.%, mainly due to the insulating polymer layer deposited on the surface of nanotubes. Electromagnetic response of prepared materials was investigated in broadband region (0.01–4 and 26–36 GHz). It was found that MWNT/PSt composites are almost radiotransparent for low frequency region and possess high absorbance of EM radiation at higher frequencies.

CNT/PMMA Electromagnetic Coating: Effect of Carbon Nanotube Diameter

The study is devoted to electromagnetic (EM) response properties of polymethylmetacrylate (PMMA) filled with multi-walled carbon nanotubes (MWNT) with two different average diameters (9 and 12–14 nm). The EM attenuation and reflection in the Ka-band (26–37 GHz) provided by PMMA/MWNT were measured as a function of the functional filler content (up to 2wt%). The constitutive parameters of PMMA/MWNT composites in microwave frequencies have been found to be strongly dependent on both the nanocarbon percentage and CNT mean diameter.

ELECTRON-ELECTRON INTERACTION IN CARBON NANOSTRUCTURES

The electron-electron interaction in carbon nanostructures was studied. A new method which allows to determine the electron-electron interaction constant

Electromagnetic shielding properties of MWCNT/PMMA composites in Ka-band

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Multi‐walled carbon nanotubes with ppm level of impurities

from the analysis of quantum correction to the magnetic susceptibility and the magnetoresistance was developed. Three types of carbon materials: arc-produced multiwalled carbon nanotubes (arc-MWNTs), CVD-produced catalytic multiwalled carbon nanotubes (c-MWNTs) and pyrolytic carbon were used for investigation. We found that

Controllable electromagnetic response of onion‐like carbon based materials

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Electrophysical properties of multiwalled carbon nanotubes with various diameters

=0.2 for arc-MWNTs (before and after bromination treatment);

Influence of surface layer conditions of multiwall carbon nanotubes on their electrophysical properties

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