Sergey I. Moseenkov

Carbon Onion Composites for EMC Applications

A novel lightweight onion-like carbon (OLC)-based polymer composite with high electromagnetic (EM) shielding properties is presented. OLC have been produced via the large-scale production technology based on the annealing of detonation nanodiamond under vacuum conditions (or in inert atmosphere). EM shielding effectiveness has been tested in the frequency range of 26-37 GHz. The highest EM attenuation at 36.6 GHz reaching -34 dB was observed for polymethylmethacrylate films comprising 20 wt.% of OLC. The shielding effectiveness data collected for microwave frequencies were found to correlate well with the electrical resistivity measurements by four-probe method as well as conductivity measurements provided by the broadband dielectric spectroscopy (20 Hz-3 GHz). It was proved experimentally that OLC EM shielding capacity can be optimized by varying the nanoonion cluster size and nanodiamond annealing temperature so that effective EM coatings can be produced. Both the experimental observations and theoretical simulations demonstrate that even small (smaller than percolation threshold) additions of OLC particles to a polymer host can noticeably modify the composite response to EM radiation.

Influence of Humidity on Dielectric Properties of PMMA Nanocomposites Containing Onion-Like Carbon

Results of broadband dielectric spectroscopy (20 Hz–1 MHz) of a novel polymer composite based on onion-like carbon (OLC) are presented. The measurements were performed by cooling and heating in a wide temperature range (240 K–420 K). After heating the dielectric permittivity strongly increases, β relaxation slows down while γ relaxation becomes negligible. The observed behaviour of relaxations suggests that dielectric properties of presented composite without additional heating are strongly influenced by extrinsic humidity. The increase of the OLC fillers concentration (up to 1 wt%) has been found to strongly increases the glass transition temperature of OLC-based polymethyl methacrylate (PMMA) composite, however, an effect of the OLC inclusions on the beta transition of the given nanocomposites is less expressed.

Laser Bleaching of Carbon Nanotubes Suspension in N,N- Dimethylformamide

Laser Bleaching of Carbon Nanotubes Suspension in N,N- Dimethylformamide It is shown experimentally that the multiwall carbon nanotubes (MWNTs) suspension in N,N-dimethylformamide (DMF) irreversibly bleaches in a wide spectrum range under a pulsed nanosecond laser radiation at the wavelength of 532 nm. According to the data of the transmission electron microscopy (TEM), the Raman spectroscopy and the reflection infrared spectrometry the bleaching is shown to be caused by MWNTs degradation, with the formation of new chemical bonds which result from the laserinduced chemical reactions between MWNTs and DMF molecules.

Carbon nanotubes and carbon onions for modification of styrene-acrylate copolymer based nanocomposites

Styrene acrylate polymer (SAC) nanocomposites with various carbon nanofillers (multiwalled carbon nanotubes MWCNTs and onion like carbon OLC) are manufactured by means of latex based routes. Concentration of the carbon nanofillers is changed in a broad interval starting from 0.01 up to 10 wt. %. Elastic, dielectric and electromagnetic properties of SAC nanocomposites are investigated. Elastic modulus, electrical conductivity and electromagnetic radiation absorption of the investigated SAC nanocomposites increase along with rising nanofiller content. The effect of the addition of anisometric MWCNTs on the elastic properties of the composite is higher than in the case of the addition of OLC. Higher electrical conductivity of the OLC containing nanocomposites is explained with the fact that reasonable agglomeration of the nanofiller can promote the development of electrically conductive network. Efficiency of the absorption of electromagnetic radiation depends on the development of conductive network within the SAC matrix.

Electromagnetic response of polymer composites with quasi-spherical nanocarbon inclusions: theory below the percolation threshold

Abstract The linear electromagnetic response of polymer composite with nanocarbon inclusions was modeled for a random multi-component system with particles and clusters of different shape and size. The results of the generalized effective medium Maxwell-Garnett theory below the percolation threshold demonstrate good coincidence with the experimental data for onion-like carbon-based polyurethane composites collected in a quasi-static regime (at 129 Hz) in a broad temperature range.