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Abstract
Polymers are high molecular weight compounds (molecular mass ranges from 10.000 to more than 1.000.000 g /mole), consisting of long – chain molecules made up of repeating units usually a back-bone of carbon atoms. Polymers are either polar or non-polar depending on the electrical symmetry of the molecules. If the centers of positive and negative charge are not coincident, a permanent dipole moment exists in the molecule whose magnitude (μ=qd) is given by the total positive and negative change (q) multiplied by the separation between them (d). If the centers are coincident, the molecules possess no dipole moment and are called non- polars.
As an electric field is applied to polar molecules, the dipoles orient in the same direction of applied field which leads to the so called orientation polarization. The electric field causes also elastic displacement of electrons from their equilibrium position-giving rise to the electronic polarization. Quasi-elastic displacement of atoms or groups of atoms with respect to each other leads to atomic polarization. Interfacial polarization occurs in heterogeneous system where the conductivity and dielectric properties (permittivity ε/ and dielectric loss ε//) of the constituents are different. Upon removal of the field the molecules relax to the equilibrium state. Relaxation time is defined as the time necessary for polarization to decay to 1/e of the value obtained under the influence of external filed. The study of dielectric relaxation of polymers is a powerful tool for the study of molecular motions and manner. This study achieved by analyzing of dielectric loss spectrum (ε// against frequency ) using the different spectral functions commonly used in dielectric research ,such as Deby (Mantas. P.Q, 1999), Cole.