Dielectric relaxation studies of higher order alcohol complexes with amines using Time Domain Reflectometry

Dielectric relaxation study of amine-alcohol mixtures have been carried out for different concentrations at 303 K. Time Domain Reflectometry (TDR) in reflection mode has been used to measure the reflection coefficient in the frequency range of 10 MHz to 20 GHz. The bilinear calibration method has been used to obtain dielectric quantities viz., static dielectric constant (epsilon(0)) and relaxation time (tau). Using these fundamental dielectric quantities the parameters like the Bruggeman factor, Kirkwood correlation factor and excess relaxation time were evaluated. The Bruggeman factor (F-BM) shows a positive deviation for pyridine [PYR] with the alcohol system and it shows a negative deviation for triethylamine [TEA] with the alcohol system. The effective Kirkwood correlation factor (g(eff)) is almost unity for amines and > 1 for alcohols and their mixtures, showing parallel orientation of dipoles. The relaxation time is increasing with increasing chain length of the alcohols and it is decreasing with increasing amine concentration. The enthalpy of activation (Delta F-tau,) for the dielectric relaxation is always greater than the theoretically predicted values for all the mixtures studied. (c) 2005 Elsevier B.V. All rights reserved.