Dielectric relaxation study of binary and ternary diol(s)/mono-alcohol mixtures in cyclohexane

The dielectric relaxation of binary and ternary diol(s)/monohydric alcohol diluted with a non-polar solvent (cyclohexane) has been studied. Different diols of different chain lengths and OH groups positions and three mono-alcohols namely n-butanol, n-hexanol and cyclohexanol are used. The relaxation spectra have been analyzed in two Debye terms. The predominating term is related to the association process. Its variation with the viscosity eta is also considered. A good correlation exists between dielectric parameters and the number density of dipoles N-D for ternary and quaternary mixtures of the same alcoholic concentration X in mel. Values of S-R/N-D, (which is proportional to the dipole moment mu), relaxation time tau (1), and relaxation strength G(1) increase with the increase in concentration N-D as well as the diols chain length, with the exception of those having the OH- group in the positions 1,2. They have low values which could be due to intramolecular hydrogen bonding. This may lead to the conclusion that the two OH- groups are close to each other so that intramolecular hydrogen bonding could occur. (C) 2000 Elsevier Science B.V. All rights reserved.