Preparation and EMI shielding performance of epoxy/non-metallic conductive fillers nano-composites

Abstract

Nonmetallic conductive materials such as inherently conducting polymers (ICPs) and carbon nanomaterials play an important role in the manufacturing of electrically conductive polymer nanocomposites for Electromagnetic Interference (EMI) shielding applications. In this study, the electrical, dielectric and EMI shielding properties of epoxy (E)/non-metallic conductive materials are investigated. Polyaniline (PANI) as an ICP, graphene and multi-walled carbon nanotubes (MWCNTs), as the most well-known carbon nanomaterials, have been selected in order to make conductive epoxy nanocomposites. The composites were prepared through solvent mixing method and characterized by the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and electrical conductivity measurements. Furthermore, dielectric properties of epoxy nano composites were measured by reflection/transmission method using a vector network analyzer (VNA) in the frequency range of 8.2–12.2 GHz. It was observed that both real and imaginary parts of permittivity increase with CNT and thermally reduced graphene oxide (TRGO) loadings. Highest dielectric loss values were observed for E/PANI (35 %) composites, while dielectric constant was highest for both E/PANI (35 %) and E/TRGO (3%) nanocomposites. Furthermore, the EMI Shielding Effectiveness (SE) was higher at high loadings of conductive fillers. The maximum reflection loss was observed for E/CNT (2.5 %) and E/PANI (15 %); in fact, E/PANI (15 %) exhibited a relatively broad effective bandwidth (i.e., reflection loss<-10 dB) of 3.6 GHz, while this parameter is 2.1 GHz for E/CNT (2.5 %).