The dielectric relaxation of mixtures of water and primary alcohol

Abstract

Dielectric measurements over a microwave frequency range 10 MHz–15 GHz were carried out by the use of new time domain reflectometry equipment on the mixtures of water with five primary alcohols, viz., methanol, ethanol, and n-propanol in the concentration range 0≤x≤1 and n-butanol and amyl alcohol in the range 0≤x≤0.5 at room temperature; x being the mole fraction of water. The systems of water and two alcohols of low molecular weight are characterized by a single relaxation with a distribution parameter of the unity or near to it. The molecular reorientation in the mixtures as well as water and these alcohols is a cooperative process involving a large number of molecules with the hydrogen-bond linkages (O–H⋅⋅⋅O). Dielectric behavior of the mixtures of water and methyl or ethyl alcohol is due to the structure of a hydrogen-bonded network being microscopically homogeneous. Microscopic heterogeneity occurs in the mixtures of water and higher alcohols.