Test of the entropy basis of the Vogel-Tammann-Fulcher equation. Dielectric relaxation of polyalcohols near T_g

We describe a family of hydrogen-bonded molecular liquids in which transport processes all appear to be strongly coupled and which exhibit relaxation times conforming to the Vogel-Tammann-Fulcher (VTF) equation τ = τ₀ exp(B/[T - T₀]) over as much as 12 orders of magnitude in τ. For such systems a stringent test of the identity of the VTF equation T₀ and the Kauzmann isoentropy temperature T_K can be made. New data on dielectric relaxation times extending into the glass transformation range are presented for three polyalcohols, and heat capacity data for crystalline and liquid ethylene glycol are also reported. Estimates of the Kauzmann temperature, T_K, at which the internally equilibrated supercooled liquid would have the same entropy as the crystal, are made. Despite a threefold variation in T_K, these are found to be close to the best-fit VTF equation T₀ parameter and even closer to the T₀ value obtained by adding the constraint B = 12.7T₀ to the analysis.