Dielectric and infrared studies of radio frequency processes in some alcohols

Abstract

In this thesis, the results of dielectric studies on a number of aliphatic alcohol molecules with variable chain lengths are presented. This investigation was complemented by infrared and viscosity measurements. Dielectric studies were confined to the radio frequency range using an H.P. 419lA RF Inpedance Analyzer. The experimental data, as a function of frequency and temperature, were subjected to analysis by a series of computer programs written in APL language. The activation energy barriers for the dielectric relaxation were obtained by application of the Eyring rate equation. Initially, a number of pure liquid alcohol molecules were studied with increasing chain length in a wide temperature and frequency range. The effect of size on the relaxation parameters could then be revealed. In all cases a Debye type process was observed which is in accordance with the literature report A few of these alcohols were also studied in a variety of solvents ranging from inert to strongly interacting. The experimental relaxation times were compared with the theoretical ones obtained using Higasi's theory of the dielectric relaxation mechanism. Furthermore, the relaxation parameters were analysed in terms of solute-solute and solute-solvent interactions. The importance of chain length on the associative equilibria was examined. Methanol, which has no chain length and no intramolecular motion within the experimental temperature and frequency ranges, was selected for this purpose. A detailed dielectric study for this alcohol was carried out in different media. An attempt was made to gain insight into the impact of steric hindrance on the relaxation times and energy parameters. Small alcohols were substituted by larger alcohol molecules in three component systems. The position of the dipole was varied for different alcohols in two component systems. These studies constitute the latter part of this thesis.