Dielectric spectroscopy relies on the presence of dipolar groups to drive the molecular relaxation mechanisms inherent in a sample material. The prima facie response of the material might be expected to depend only on electrically asymmetric functional groups with their intrinsic dipole moment. Although motion of the dipole is induced directly by the action of the applied field, neighbouring groups can modify its response and may even restrict its mobility. Considerable information onthe motions of both dipolar and non-dipolar segments of polymer molecules is, therefore, possible using dielectric spectroscopy.
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