Broadband dielectric study on the water-concentration dependence of the primary and secondary processes for triethyleneglycol-water mixtures

Broadband dielectric measurements for triethyleneglycol (3EG)-water mixtures with various concentrations were performed in the frequency range of 100.3em0exμHz--100.3em0exGHz and in the temperature range of 130--2980.3em0exK. For each mixture, the separation of the primary (α) and secondary processes is observed below the crossover temperature, TC. In the case of 80--1000.3em0exwt0.2em0ex% 3EG-water mixtures, the Kohlrausch-Williams-Watts--type primary process above TC continues to the α process below TC, and an additional secondary process is observed in the frequency range higher than that of the α process below TC. On the other hand, the primary process for 65 and 700.3em0exwt0.2em0ex% 3EG-water mixtures above TC continues to the higher-frequency secondary process below TC, and an additional α process appears at a frequency lower than that of the secondary process. The contribution of water to relaxation processes is discussed, to clarify the molecular mechanism of the separation behavior. The characteristic separation behavior of the relaxation processes for high-water-content 3EG-water mixtures is due to the existence of excess water, which cannot move cooperatively with solute 3EG molecules below TC.