Comparison of shear and dielectrics in highly viscous liquids

TL;DR

This paper derives a relation between shear and dielectric spectra in highly viscous liquids, examining its validity across different substances and discussing implications for strong correlations.

Contribution

It introduces a theoretical relation linking shear and dielectric spectra in viscous liquids, tested against experimental data for the first time.

Findings

Relation holds for some substances but not all

Experimental data show variability in the relation's validity

Discusses connection to strong correlation theories

Abstract

A relation between shear and dielectric spectra is derived for highly viscous liquids with a small rotational contribution $\Delta\epsilon$ to the dielectric constant. It is valid if the shear fluctuations and the electric dipole fluctuations have the same spectrum. The comparison to literature data, taken under carefully controlled conditions to ensure samples from the same charge and the same temperature control in both measurements, indicates that the relation may be fulfilled or not depending on the substance. The connection to recent work on strong correlations is discussed.