Effect of Nickel-spinal-Ferrites on EMI shielding properties of polystyrene/polyaniline blend

Magnetic and electrically conductive polymeric nanocomposites were fabricated using polystyrene (PS) as matrix, Nickel Ferrites (NiFe) as magnetic nanofiller and polyaniline (PANI) as electrically conductive nanofiller. Electromagnetic interference (EMI) shielding and infrared (IR) blocking are the main application of these nanocomposites. PANI and NiFe were successfully prepared by chemical and co-precipitation methods respectively. The successful fabrication of nanofillers was confirmed by the X-ray diffraction technique. DC conductivity and dielectric properties were first analyzed and a huge increase in both dielectric constant and DC conductivity was observed. Dielectric Constant seemed to be increased from 2.2 for PS to 5.5 for PS/PANI/NiFe composite. For the measurement of EMI shielding effectiveness (SE), Vector Network Analyzer was used in 0.1-20 GHz frequency range. IR spectroscopy was used to measure IR transmission in near-infrared (NIR) region of 700-2500 nm wavelength range. PS film is transparent for both NIR waves and microwaves, by observing almost 90% transmission in the NIR range and about - 3 dB SE in the microwave region. IR transmission reduces to less than 0.5% for PS/PANI/NiFe composite in the whole NIR range. Also, in the microwave region, - 3 dB shielding enhanced to less than - 35 dB in a broad range of frequency from 0.1 to 20 GHz.