PNNL

Abstract

Workability and meltability of molten glass are evaluated in terms of the working and melting lengths, i.e., as the temperature intervals within which glass-forming and melting operations are performed. Both lengths are functions of the glass melt fragility and the glass transition temperature. By the augmented Adam-Gibbs equation, the glass melt fragility is a function of configuration entropy in terms of the fragility exponent and the maximum configuration entropy of the fully depolymerized melt at high temperature. Both working length and melting length are high for strong glasses and decrease as the melt fragility increases. Analytical formulas obtained for three three-parameter viscosity models (VFT, AM, and MYEGA) express the working length as a function of the fragility index; the models agree on the relationship between workability and fragility of glasses.