Glass transitions in viscous monohydroxy alcohols: Calorimetry versus dielectric relaxation

An extensive comparison of the calorimetric and dielectric measurements of the glass transitions in both monohydroxy alcohols and other molecular liquids is presented, with only these alcohols displaying an additional pronounced dielectric Debye peaks. It is found that the calorimetric T _g's of the non-Debye liquids with moderate cooling and heating rates (±20 K • min ^-1, for example) are slightly higher than the kinetic ones which are determined as the temperatures at which the relaxation time is 100 s. As the difference does not exceed 3 K, this relation of calorimetric and kinetic T _g's is used as 'standard.' Two kinetic glass transitions from the dielectric relaxation of Debye type monohydroxy alcohols are identified, and it is found that the Debye process is not the signature of the glass transition.