Electromagnetic attenuation by conducting polymers composites

Polyaniline (PANI) based conducting polymer composites were prepared for electromagnetic attenuation in microwave region. Seven different PANI polymers (PANI-1 to PANI-7) were synthesized by various methods using different dopants like Hydrochloric acid, sulphuric acid, p_toluene-sulphonic acid, dodecylbenzenesulphonic acid with their permittivity, capacitance and conductivity characterized. Their composite coatings with Polyurethane paint and Poly(vinyl acetate) were prepared by homogeneously blending. For microwave power attenuation studies PANI-PU coatings of 50-micron thickness were done on test aluminium plates. Loading of polyaniline in each sample was 15 % w/v of the PU emulsion paint. Microwave power attenuation observed in all PANI-PU samples was broadband and generally showed two maxima between 8-11 GHz region, measured by HP vector network analyser using an APC-7 coaxial cable and a rectangular waveguide. For PANI-3, Maximum corrected Power loss was 72%, while for PANI-6 and PANI-4 it was 62-64% in 8-9 GHz region, for PANI-2 it was 66% in 8.5 GHz region.