STUDY OF DIELECTRIC-RELAXATION IN POLYMER ELECTROLYTES

An attempt has been made to study the relaxation characteristics of PV A-H3PO4 and PVA-H2SO4 complex electrolytes in the form of thin films. Various dielectric parameters such as dielectric constant (epsilon'), dielectric loss (epsilon '') and loss tangent (tan delta) have been de termined in the temperature range 20-160 degrees C at different freque ncies and molar ratios. Using Cole-Cole plots (epsilon '' vs epsilon') , the values of epsilon(s) (static dielectric constant), epsilon(infin ity) (infinitely large frequency dielectric constant) and relaxation t imes have been calculated at room temperature. Relaxation time is dete rmined from the variation of loss tangent with temperature at differen t frequencies. It is observed that relaxation characteristics show Arr henius type behaviour and there is a decrease in activation energy wit h an increase in acid concentration for various complexes. The study o f dielectric relaxation as a function of temperature at constant frequ ency shows two types of relaxation processes which are interpreted in terms of dipole-segmental motion (alpha-relaxation) and side chain dip ole group motion (beta-relaxation). (C) 1998 Elsevier Science Ltd. All rights reserved.