Characterization of polymers by dielectric spectroscopy

Polymers are dielectric materials whose application can be to store and isolate "two electricities". As this function is never perfect, the dielectric is usually represented by a complex impedance. By accurately measuring the modulus and argument of the polymer's impedance, we obtain its main dielectric characteristics: permittivity, resistivity and dissipation factor.

Low-frequency dielectric spectroscopy is a technique that provides efficient access to these quantities and their frequency dependence.

Beyond the purely electrical characteristics of the polymer, dielectric spectroscopy can also reveal aging phenomena, detect the presence of water, highlight the presence of heterogeneities and, more generally, obtain information on the polymer's structure. Finally, this technique can help diagnose construction defects, such as cavities between electrical insulation layers, or the porosity of dielectric material.

Advances in signal processing and electronics over the last twenty years have brought this technique to maturity. Its universal character makes it an essential technique in the early stages of dielectric studies. This article is therefore dedicated to it...

The field of application is electrical insulation and electricity storage. The notion of complex impedance is introduced, different measurement techniques are presented and methods for identifying physical phenomena are proposed.