Dielectric relaxation in glycine-water and glycine-ethanol-water solutions using time domain reflectometry

摘要

Dielectric relaxation measurements on water-ethanol-glycine ternary system were carried out using time domain reflectometry (TDR) at 25, 30, 35, and 40degreesC in the frequency range from 10 MHz to 10 GHz. Glycine-ethanol-water solutions are prepared with different concentrations of ethanol (0, 5, 10, 15, 20, and 30%) and also for different glycine molar concentrations (0, 0.2, 0.4, 0.6, 0.8, and 1 M). The dielectric relaxation parameters are measured for aqueous glycine solutions also to compare the results with those for the glycine-ethanol-water ternary system. For all the mixtures considered, only one relaxation peak was observed in this frequency range. All the mixtures display a Cole-Davidson dispersion. The relaxation peaks shift to lower frequency with an increase in glycine concentration and also with ethanol concentration. The logarithm of the relaxation time log(tau) shows a nonlinear relation with glycine concentration which implies a change of relaxation mechanism with glycine concentration. The dielectric strength Deltaepsilon for these mixtures shows a nearly linear relation with glycine molar concentration.