Ceramics-Silikáty 49, (2) 91 - 96 (2005) |
|
MODELING OF THE REVERSIBLE PART OF STEPSCAN DSC MEASUREMENT OF THE GLASS TRANSITION
|
Chromčíková Mária 1, Holubová Jana 2, Liška Marek 1,
Černošek Zdeněk 3,
Černošková Eva 4
|
1 Vitrum Laugaricio (VILA) - Joint Glass Center of Institute of Inorganic Chemistry SAS,
Alexander Dubček University of Trenčín and RONA Lednické Rovne, Študentská 2, 911 50 Trenčín, Slovak Republic
2 Department of General and Inorganic Chemistry, University of Pardubice, nám. Legií 565, 532 10 Pardubice, Czech Republic
3 Research Centre of University of Pardubice and Institute of Inorganic Chemistry of Czech Academy of Sciences,
nám. Legií 565, 532 10 Pardubice, Czech Republic
4 Joint Laboratory of Solid State Chemistry of Institute of Macromolecular Chemistry of Czech Academy of Sciences
and University of Pardubice, Studentská 84, 532 10 Pardubice, Czech Republic
|
Keywords: Glass, Glass transition, Dynamic DSC, StepScan DSC, Relaxation phenomena, Thermodynamic modeling
|
The reversible part of StepScan DSC record of a glass in the region of the glass transition was interpreted as a measure of
the conversion degree α of the A ↔ B type equilibrium reaction identified with a reversible part of glass ↔ undercooled melt
transition. The temperature course of the conversion degree, α(T), was expressed in terms of the temperature dependence of
the equilibrium constant alternatively with the temperature dependent and temperature independent reaction enthalpy. Experimental
data of eight various inorganic and organic glasses were fitted by the proposed model. The formalism of temperature
independent formal reaction enthalpy was sufficient to reach an acceptable quality of the fit, i.e. the fit accuracy level of an
average experimental error. The model of temperature dependent formal reaction enthalpy was found inappropriate due to
strong inter-correlations between the regression parameters. In contrary to the previously reported model the proposed model
yields the maximum conversion rate at the conversion degree lower than 0.5. |
 PDF (0.2 MB) |
|
