Pm. Mehl, DETERMINATION OF ENTHALPY RELAXATION-TIMES USING TRADITIONAL DIFFERENTIAL SCANNING CALORIMETRY FOR GLYCEROL AND FOR PROPYLENE-GLYCOL, Thermochimica acta, 272, 1996, pp. 201-209
The isothermal enthalpy relaxation of glycerol and propylene glycol is
studied for different subglass transition annealing temperatures usin
g our usual method. The kinetics of the glass transition is analyzed u
sing the Kohlrausch-Williams-Watts model. The Vogel-Fulcher-Tamman mod
el was previously used for the spectrometric specific heat analysis of
glycerol and propylene glycol by Birge and co-workers at temperatures
higher than the glass transition. We present the comparison of the en
thalpy relaxation times as a continuation of their data for sub-glass
transition temperatures. The results show an intermediate thermal doma
in between the liquid state and the glassy state. The relaxation times
are experimentally determined within the model of the non-exponential
relaxation theory. The effects of the cooling and warming rates are a
lso investigated for their relevance in the determination of the relax
ation times.