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 scannin g calorimetry are used to study the existence of clathrate hydrates in aque ous solutions Of a number of alcohols and nonhydrogen-bonded liquids. The a queous solutions studied are those of methanol, ethanol, 2-propanol, tert-b utyl alcohol, acetone, and p-dioxane. The corresponding solid-liquid phase diagrams are also determined to support the dielectric results. Evidence fo r the existence of clathrate hydrates in 2-propanol and tert-butyl alcohol is provided. The clathrate hydrate of 2-propanol is metastable. No clathrat e structure is found in methanol mixtures. The composition of the new clath rate 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 th e, two hydrates of ethanol) has been studied down to its kinetic freezing t emperature T-g and is analyzed in terms of the Arrhenius equation. Also stu died are the relaxation rates of the clathrate hydrates of acetone, tetrahy drofuran, and p-dioxane down to their respective T(g)s. The nature of the d ielectric relaxation is discussed.