Nanocomposites and nanomaterials

Microwave shielding and absorbing properties of single- and multilayer structures based on two-phase filler/epoxy composites
Vovchenko L.L.1, Lozitsky O.V.1, Matzui L.Y.1, Oliynyk V.V.2, Zagorodnii V.V.2
1 Department of Physics, 2 Department of Radiophysics, Electronics, and Computer System, . Taras Shevchenko National University of Kyiv, Volodymyrska str., 64/13, Kyiv, 01601, Ukraine
E-mail: Olozitsky@gmail.com; vovch@univ.kiev.ua 

The microwave absorbing and shielding properties of epoxy composites (CMs) with multiphase filler (nanocarbon+TiO2 (or Fe) were studied in frequency range (1-67) GHz. The content of TiO2 or Fe particles was fixed at 35wt% and 30wt.%, respectively, while the content of carbon filler (carbon nanotubes (CNT) or graphite nanoplatelets (GNP) was varied from 1 to 5 wt.%. It was found that electromagnetic  shielding efficiency  SET  is increased with nanocarbon content,
	especially for CNT/Fe/epoxy CMs. The measured complex permittivity and permeability data were used for simulation of the reflection loss RL. It was shown that more pronounced RLmin= (22-33) dB is observed for 2-3wt.%. CNT content in CNT/Fe/epoxy CMs (Fig. 1). The effective bandwidth of RLminat level 10 dB can achieve (8-12) GHz.
The absorbing performance of multilayer composite structures may be calculated using electromagnetic parameters of single-layer  absorbers based on	
Figure 1. Simulated data on reflection loss RL for various specimen thickness of 2%CNT/Fe/epoxy CM
		
three-phase composites. To minimize the reflection of electromagnetic waves on the first surface air-shield the optimization of thickness of each composite layer should be performed.