Conduction mechanism in Polyaniline-flyash composite material for shielding against electromagnetic radiation in X-band & Ku band

β–Naphthalene sulphonic acid (β–NSA) doped polyaniline (PANI)–flyash (FA) composites have been prepared by chemical oxidative polymerization route whose conductivity lies in the range 2.37–21.49 S/cm. The temperature dependence of electrical conductivity has also been recorded which shows that composites follow Mott's 3D–VRH model. SEM images demonstrate that β–NSA leads to the formation of the tubular structure with incorporated flyash phase. TGA studies show the improvement in thermal stability of composites with increase in loading level of flyash. Complex parameters i.e. permittivity (ɛ* = ɛ′- iɛ″) and permeability (μ*=μ′- iμ″) of PANI-FA composites have been calculated from experimental scattering parameters (S11 & S21) using theoretical calculations given in Nicholson–Ross and Weir algorithms. The microwave absorption properties of the composites have been studied in X-band (8.2 – 12.4 GHz) & Ku–Band (12.4 – 18 GHz) frequency range. The maximum shielding effectiveness observed was 32dB, which strongly depends on dielectric loss and volume fraction of flyash in PANI matrix.