Nanocomposites and nanomaterials

Dielectric and microwave shielding properties of three-phase composites graphite nanoplatelets/carbonyl iron/epoxy resin
Lozitsky O.V.1, Vovchenko L.L.1, Oliynyk V.V.1, Zagorodnii V.V.1, Len T.A.1, Matzui L.Y.1, Milovanov Yu. S.2
1Department of Physics and 2Institute of High Technologies, Taras Shevchenko National University of Kyiv, Volodymyrska str., 64/13, Kyiv, 01601, Ukraine
E-mail: Olozitsky@gmail.com

The electrical properties of three-phase composite materials (CMs) graphite nanoplatelets/carbonyl iron/epoxy resin (GNP/Fe/epoxy) with 30 wt.% of Fe and (1-5) wt.% of GNP were studied by measuring DC conductivity and AC impedance spectra in the frequency range up to 2 MHz. The microwave shielding properties were measured in Ka-band of electromagnetic radiation (EMR). The significant increase of permittivity was observed for three-phase CMs with the increase of GNP content  compared  with two-phase GNP/epoxy CMs.  Such change  in the
	permittivity may be explained by the presence of the large number of the additional conductive Fe particles acting as “artificial dipoles” and contribution of large interface polarization in the frequency range 1 kHz-2 MHz [1]. The observed sufficient increase of EMR shielding (|S21| in dB) in Ka-band for high GNP content correlates with DC electrical conductivity increase (Fig. 1). The increase of the sample thickness d leads to the increase of shielding efficiency due to increase of EMR absorption term at higher shields’ thickness.	
Figure 1. EMR transmission index S21 of GNP/Fe/epoxy composites; numbers on curves correspond to GNP content in wt.% 		

1.	Wang Z., Luo J., Zhao G.L. Dielectric and microwave attenuation properties of graphene nanoplatelet–epoxy composites // AIP Advances – 2014.- 4.-P. 017139-9.