Lightweight Polyaniline-Cobalt Coated Fly Ash Cenosphere Composite Film for Electromagnetic Interference Shielding

Thermal power plant's solid environmental waste fly ash cenosphere (FAC) is cobalt coated chemically and functionalized by in situ synthesis of polyaniline (PANI) under nitrogen atmosphere at -30 +/- 2 degrees C and characterized by various techniques. The electromagnetic interference shielding effectiveness (EMI SE) of free standing PANI/Co-FAC (PCC) films prepared by solution casting indicates an appreciable shielding. The most effective average EMI SE of similar to 30 dB was obtained for 89 +/- 3 mu m thicker flexible film over the frequency range of 12.4-18 GHz (Ku-band). Mechanistically, EMI shielding due to absorption was found to be dominant. The obtained shielding effectiveness due to absorbance (SEA) of PCC film is nearly two times higher than PC film. The microwave conductivity (sigma) of PCC film (157-184 Sm-1) is much higher than PC film (118-142 Sm-1). Moreover, the high EM attenuation constant (alpha) value of PCC film indicates excellent suitability of EMI shielding due to absorption.