On the dependence of the properties of glasses on cooling and heating rates: I. Entropy, entropy production, and glass transition temperature

The glass transition is theoretically described in terms of a generic non-equilibrium thermodynamics approach employing De Donder's structural order parameter method, appropriate expressions for the relaxation behavior of glass-forming systems and a simplified but qualitative correct model of glass-forming melts with one order parameter related to the free volume of the system. Employing this approach the behavior of a variety of thermodynamic quantities describing glass-forming systems in vitrification and devitrification processes is interpreted theoretically. The present paper is devoted to the computation of the entropy, the entropy production and the glass transition temperature in dependence on the cooling and heating rates, varying latter parameter in a broad interval. A comparison with experimental results is given and some further consequences and possible extensions are discussed briefly.

Research Highlights► The dependence of vitrification processes on cooling and heating rates is studied. ► Cooling and heating rates are varied hereby in broad intervals. ► The conventional definition of the glass transition temperature is analyzed. ► Limits of validity and an extension of the Bartenev-Ritland equation are discussed. ► The behaviour of the entropy and entropy production in vitrification is investigated.