Complex permittivity of epoxy composites with carbon nanotubes and TiO2 in microwave range

Abstract

Titanium oxide (TiO2) particles, used with conductive particles as fillers for composite materials (CMs) have recently been shown to produce high dielectric constant with low dielectric loss at frequencies up to 10 MHz. This work describes the microwave properties of L285 epoxy, filled with 1–5 wt. % of carbon nanotubes (CNTs) and 35 wt. % of TiO2 powder. A correlating dependence of the real and imaginary parts of permittivity versus CNT content has been observed, suggesting there are multiple factors taking part in formation of the permittivity with interfacial and dipole polarizations of filler clusters taking the main part. These factors can be exploited by varying the filler contents and particle size to obtain CMs with high permittivity and low dielectric loss as well as superior microwave absorbers.