Structural aspects in the dielectric properties of pentyl alcohols

Abstract

At temperatures between 0 and 60 °C densities, shear viscosities and dielectric spectra have been measured for isomers 1-pentanol, 2-pentanol, 3-pentanol, isopentylalcohol, and tert-pentanol, as well as for mixtures of these alcohols. The density and shear viscosity data are discussed in terms of deviations from ideal mixing behavior. The dielectric spectra are evaluated to yield the extrapolated static permittivity and the relaxation time of the principal (low-frequency) relaxation term. The former parameter is analyzed in view of dipole orientation correlations, the latter one is discussed in terms of the activation enthalpy controlling the relaxation process. A noticeable result is the effect of isomer structure on both the dipole orientation correlation and the dielectric relaxation. Especially the dielectric parameters of tert-pentanol deviate significantly from the relevant parameters of the other pentanols. Such deviations are considered in the light of models of hydrogen network structure and fluctuations.