Detailed study of ice clathrate relaxation: Evidence for the existence of clathrate structures in some water-alcohol mixtures

Dielectric relaxation technique (10(+6)-10(-3) Hz) and differential scanning calorimetry are used to study the existence of clathrate hydrates in aqueous solutions Of a number of alcohols and nonhydrogen-bonded liquids. The aqueous solutions studied are those of methanol, ethanol, 2-propanol, tert-butyl alcohol, acetone, and p-dioxane. The corresponding solid-liquid phase diagrams are also determined to support the dielectric results. Evidence for the existence of clathrate hydrates in 2-propanol and tert-butyl alcohol is provided. The clathrate hydrate of 2-propanol is metastable. No clathrate structure is found in methanol mixtures. The composition of the new clathrate found in 2-propanol and tert-butyl alcohol is suggested to be around A. 5H(2)O-A. 6H(2)O. The clathrate hydrate relaxation (including that: of the, two hydrates of ethanol) has been studied down to its kinetic freezing temperature T-g and is analyzed in terms of the Arrhenius equation. Also studied are the relaxation rates of the clathrate hydrates of acetone, tetrahydrofuran, and p-dioxane down to their respective T(g)s. The nature of the dielectric relaxation is discussed.