ANALYSES FOR A DIPOLAR RELAXATION IN THE FEATURELESS DIELECTRIC SPECTRUM, AND A COMPARISON BETWEEN THE PERMITTIVITY, MODULUS AND IMPEDANCE REPRESENTATIONS

The apparently featureless permittivity, epsilon', and loss, epsilon'' , spectra of a nylon 12 polymer have been analysed to reveal its dipol ar relaxation process and de conductivity. Two other representations o f the data, namely electric modulus and impedance, have been examined for their suitability in cases where overwhelmingly large contribution s from electrode impedance and de conductivity mask the dipolar relaxa tion process. In these two representations, the shape of the spectra o f the relevant quantities could be fitted to a distribution of conduct ivity relaxation times, but when the parameters obtained from such fit tings were used to calculate epsilon' and epsilon'', large discrepanci es between the calculated and measured quantities became obvious. Thus , modulus and impedance representations seem unsuitable for the analys is of the dielectric data. Critical examination demonstrated that uniq ue and reliable information is obtained only when the dielectric data were analysed in permittivity representation and interfacial (electrod e/sample) effects taken into account. The permittivity representation seems preferable to the other two representations.