Thermal and Structural Property Characterization of Commercially Moldable Glasses

In this paper, we report the development of a kinetic model for precisely predicting glass material property response to a defined molding profile. The glass viscosity, thermal expansion, and specific heat properties for two commercial optical glasses, P-SK57 and L-BAL35 were measured and are reported in this paper. These data were used with the Tool-Narayanaswamy-Moynihan (TNM) model for glass structural relaxation in order to develop a thermal expansion model that simulates the glass workpiece changes through the critical cooling profile where the final workpiece shape is determined. The results show a structural relaxation model incorporated into an ABAQUS FEM code that precisely models the thermal expansion behavior acknowledging that the theory of structural relaxation is a critical element in predicting the final size and shape of a molded lens.