ISOTHERMAL ENTHALPY RELAXATION OF GLYCEROL

The isothermal enthalpy relaxation of glycerol has been measured at 13 different annealing times at temperatures of 170, 175, 180, and 185 K. The glasses were formed by linear cooling at 0. 667 and 0. 083 K multiplied by (times) s** minus **1 in a differential scanning calorimeter (DSC). The Williams-Watts relaxation function was fitted to data of enthalpy versus time. A strong temperature dependence was found for the relaxation time. The distribution parameter, beta , showed an increase from 0. 49 at 170 K to 0. 65 at 185 K. We also found indications of an enthalpy dependence in beta . Comparison with a theory of volume relaxation showed differences between rates of volume and enthalpy relaxation.