Improving EMI shielding effectiveness and dielectric properties of polyaniline-coated polyester fabric by effective doping and redoping procedures:

Conductive polymers with their medium level of conductivity are synthetic materials that can be used as electromagnetic wave absorber. In this work, the effect of aging and washing on the surface resistivity and also the influence of efficient doping and redoping procedure on the dielectric properties and electromagnetic radiation shielding of uniformly polyaniline coated polyester fabric are investigated in the X-band frequency range. They can affect the shielding effectiveness by changing the surface resistivity and dielectric permittivity. It is found that lightweight, flexible, and thin polyaniline-coated polyester fabric sample prepared in 1:1:7 monomer:oxidant:dopant molar ratio and redoped with concentrated HCl vapor shows the highest transmission loss (53-43%) in 8.2-12.4 GHz. Compared to single layer, double and triple layer samples attenuated 71-61% and 83-77% of incident wave, respectively. Absorption was the dominant shielding mechanism. It is also demonstrated that the increment of surface resistivity due to washing of samples is compensated by the redoping process.