Glossary
Characterization of polymers by dielectric spectroscopy

Dielectric spectroscopy; dielectric spectroscopy

Technique for measuring the complex impedance of an electrical insulator as a function of frequency, and deducing its permittivity, resistivity and dissipation factor.

Permittivité réelle et imaginaire ; imaginary and real permittivity

The real component ε' is none other than the relative permittivity ε_r ; it represents (give or take a constant) the "susceptibility" of a dielectric to polarize under the effect of an electric field. The imaginary component ε" is known as the relative loss index, because it allows us to find the active power P_a dissipated by the capacitor.

Conductivité AC/DC ; ac/dc conductivity

Conductivity σ' increases with frequency according to a power law, with an exponent close to 1 at lower values (this is known as AC conductivity: σ_AC). At low frequencies, conductivity...