Study on electromagnetic properties and microwave absorbing characteristics of carbon nanofibers

In this study, carbon nanofibers (CNFs) with the typical diameter ranging from 100~300 nm were prepared via polymer blended wet-spinning method and subsequent thermal treatment. The complex permittivity (epsiv\´-jepsiv"), complex permeability (mu\´-jmu") and microwave absorption properties of carbon nanofibers/epoxy composites have been studied in Xband frequency range (8.2-12.4 GHz) using a HP8722 ES network system. epsiv\´, epsiv", epsiv\´ and epsiv" are found to increase with increased CNF contents. Measured values of these parameters were used to determine the reflection loss at various sample thicknesses, based on a model of a single-layered plane wave absorber backed by a perfect conductor. The composite with 8 wt% CNFs has shown a maximum reflection loss of -34 dB at 10.5 GHz with the -10 dB bandwidth over the extended frequency range of 8.8-12.4 GHz which covers almost the whole X-band at a thickness of 2.1 mm.