Polyurethane-Based Functionalized CNT Composites as Absorbers for Microwave Applications

In this work, we present the comparison of the electrical properties of polyurethane embedded basic carbon nanotubes (CNT) with the functionalized CNT (cobalt-iron-doped: CoFe) nanoparticles. The basic composite with CNT concentration of 5 wt% and the functionalized CoFe composites with CNT concentrations of 5%, 10%, and 20% are prepared using chemical vapour deposition (CVD) technique. The dielectric properties along with the loss tangent values are measured using an openended coaxial probe and compared in the spectral range of 0.2 - 20 GHz. The samples are also evaluated for its reflection loss measurements at normal incidence. The measurement results show that for a given thickness of the samples, the functionalized CNT composites exhibit high absorption efficiencies or lower reflection losses as compared to the basic CNT composite. Such functionalized composites can be used to replace the common heavyweight materials used for microwave applications.