Further applications of dielectric relaxation spectroscopy

Abstract

Dielectric spectroscopy is an analytical technique notable for its wide-band capability and sensitivity. It relies on the presence of charge-asymmetric functional groups (dipoles) in the material under investigation. Significantly, the motion induced by an impressed field is not exclusive but depends on the nature of the coupling to neighbouring groups, generating in each dielectric spectrum considerable information concerning both dipolar and non-dipolar segments of polymeric or other molecules. Molecular mobility in polymers is influenced by the presence of low molecular weight additives, crosslinking, branching, inter- and intra-molecular interactions from hydrogen bonds and other sources, co-polymerization, blending, and degradation, and by dielectric inhomogeneities at the boundaries between macroscopic sub-structures. Consequently, dielectric spectroscopy is appropriate for the investigation of phase morphology and miscibility, and for the characterisation of changes induced by irradiation or the presence of additives. The utility of the spectroscopy is enhanced when used in conjunction with complementary analytical techniques.