Temperature range of the liquid–glass transition

Abstract

It has been shown that the currently used method for calculating the temperature range of δT g in the glass transition equation qτ g = δT g as the difference δT g = (T 12–T 13) results in overestimated values, which is explained by the assumption of a constant activation energy of glass transition in deriving the calculation equation (T 12 and T 13 are the temperatures corresponding to the logarithmic viscosity values of logη = 12 and logη = 13). The methods for the evaluation of δT g using the Williams–Landel–Ferry equation and the model of delocalized atoms are considered, the results of which are in satisfactory agreement with the product qτ g (q is the cooling rate of the melt and τ g is the structural relaxation time at the glass transition temperature). The calculation of τ g for inorganic glasses and amorphous organic polymers is proposed.