Composites filled with carbon nanoplatelets designed as multi-layer electromagnetic shields are c... more Composites filled with carbon nanoplatelets designed as multi-layer electromagnetic shields are considered because of their interesting electromagnetic characteristics, such as high electrical conductivity and excellent microwave absorption and shielding behaviour. Layers disposal, their composition and electrical parameters, number and thicknesses are optimized through a real-coded genetic algorithm to achieve the minimization of the transmitted waves and minimization of reflection loss of the absorbing composites as coating on metal surface. Numerical design of wide frequency band radar absorbing multi-layer composite structures and highly shielding structures are presented and compared with experimental results.
The effect of filler alignment on conductive and shielding properties has been investigated in mu... more The effect of filler alignment on conductive and shielding properties has been investigated in multiwall carbon nanotubes (MWCNTs)/polymer nanocompos-ites (NCs) containing 0.05–1 wt. % of the filler. The filler alignment was produced by applying external AC electric field during the whole process of hardening. MWCNTs network formation was detected by optic microscopy. The percolation thresholds that have been found for NC with MWCNTs aligned network are of two types. The higher threshold (at 1.45 wt% of MWCNTs) is described by the statistical percolation theory. The lower one (at 0.45 wt% of MWCNTs) is the dynamic or kinetic threshold which is determined not only by the MWCNTs parameters but also depends on the electric field characteristics and viscosity of polymer matrix. The influence of the character of MWCNTs distribution in epoxy resin on electrodynamic characteristics of the prepared NCs has been investigated in a wide frequency range (26–53 GHz). The experiment has revealed the anisotropy of permittivity: the permittivity in the parallel direction is higher than that in the direction perpendicular to MWCNTs axis. The analysis of the obtained results in terms of Maxwell-Garnett theory with taking into account the distribution function of MWCNTs in NCs shows that the anisotropy factor ¦ D 2. The investigation of microwave absorbing properties has shown that the absorption peak as well as the absorption bandwidth strongly depends not only on MWCNTs concentration in NCs, but also on the character of MWCNTs distribution with respect to the direction of electromagnetic wave propagation.
Composites filled with carbon nanoplatelets designed as multi-layer electromagnetic shields are c... more Composites filled with carbon nanoplatelets designed as multi-layer electromagnetic shields are considered because of their interesting electromagnetic characteristics, such as high electrical conductivity and excellent microwave absorption and shielding behaviour. Layers disposal, their composition and electrical parameters, number and thicknesses are optimized through a real-coded genetic algorithm to achieve the minimization of the transmitted waves and minimization of reflection loss of the absorbing composites as coating on metal surface. Numerical design of wide frequency band radar absorbing multi-layer composite structures and highly shielding structures are presented and compared with experimental results.
The effect of filler alignment on conductive and shielding properties has been investigated in mu... more The effect of filler alignment on conductive and shielding properties has been investigated in multiwall carbon nanotubes (MWCNTs)/polymer nanocompos-ites (NCs) containing 0.05–1 wt. % of the filler. The filler alignment was produced by applying external AC electric field during the whole process of hardening. MWCNTs network formation was detected by optic microscopy. The percolation thresholds that have been found for NC with MWCNTs aligned network are of two types. The higher threshold (at 1.45 wt% of MWCNTs) is described by the statistical percolation theory. The lower one (at 0.45 wt% of MWCNTs) is the dynamic or kinetic threshold which is determined not only by the MWCNTs parameters but also depends on the electric field characteristics and viscosity of polymer matrix. The influence of the character of MWCNTs distribution in epoxy resin on electrodynamic characteristics of the prepared NCs has been investigated in a wide frequency range (26–53 GHz). The experiment has revealed the anisotropy of permittivity: the permittivity in the parallel direction is higher than that in the direction perpendicular to MWCNTs axis. The analysis of the obtained results in terms of Maxwell-Garnett theory with taking into account the distribution function of MWCNTs in NCs shows that the anisotropy factor ¦ D 2. The investigation of microwave absorbing properties has shown that the absorption peak as well as the absorption bandwidth strongly depends not only on MWCNTs concentration in NCs, but also on the character of MWCNTs distribution with respect to the direction of electromagnetic wave propagation.
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