Dielectric Investigation of Doped Poly ( methyl acrylate ) ( PMA ) Conducting Polymer Films

Dielectric behavior of doped poly (methyl acrylate) (PMA) Conducting polymer has been investigated in electret state. The permittivity and loss factor have been obtained at varying temperatures from 30 to 230C and different frequencies 05,10,25 and 50 kHz for different electrode configurations of doped poly (methyl acrylate) (PMA) conducting polymer films of 25μm thickness. The capacitances are found to increase with the increase in temperature for similar electrode Al-Al system, however, in case of dissimilar electrode Al-Cu combinations, a shoulder peak is found at 110±10C and remaining variations are the same, as found in case of similar electrode system. The variation of permittivity with temperature is attributed to thermal expansion in the lower temperature region and to the orientation of dipolar molecules in the neighborhood of glass tuber transition temperature Tg (180C) of doped poly (methyl acrylate) (PMA) conducting polymer. The variation of loss factor with temperature at different constant frequencies show two loss maxima, first at 90±10C and second at 108±10C, below and near Tg of PMA, corresponding to α and β relaxations of the polymer which shift to lower temperatures as frequency is decreased. The increase in losses with the decreases of frequency is ascribed to the increase in conductivity of the polymer.