Dielectric relaxation and thermal stability of polycarbonate doped with MnCl2 salt

Polycarbonate (PC)/MnCl2 composites have been prepared in order to study the influence of MnCl2 salt on the dielectric properties (resistivity rho, permittivity epsilon', dielectric loss epsilon '', dielectric relaxation time 'tau' and dielectric relaxation process) and thermal stability of PC/MnCl2 composites. The dielectric study was carried out over a frequency range from 10 Hz to 306 kHz at room temperature as a function of frequency and salt concentration. Permittivity data was fitted in the frequency domain using Yan and Rhodes model in order to estimate the relaxation times for PC composites. As expected, the resistivity of the composites decreases with increasing of salt concentration and frequency. Also, it was found that, addition of MnCl2 salt to PC host changes the dielectric properties of PC, mainly, broadening dielectric spectra, increases permittivity and dielectric loss, shortening relaxation time and reduces thermal stability of PC and PC composites. Results reveal that the relaxation process of these composites is due to ionic conductivity relaxation with a single relaxation time and not due to viscoelastic relaxation, while in case of pure PC is due to viscoelastic relaxation.