Measurement of Stress‐Optical Coefficient and Rate of Stress Release in Commercial Soda‐Lime Glasses

Abstract

A method is described for measuring the stress‐birefringence properties of soda‐lime glasses in the range 23° to 650°C. Data on three glasses show that the stress‐optical coefficient increases slowly with temperature, reaching a definite maximum in the range 570° to 590°C. The same apparatus was used to measure the rate of stress release in two of these glasses. Data obtained under thermal equilibrium conditions can be represented by equations that suggest that two or more concurrent mechanisms are involved in stress release in these glasses within the viscosity range log 12 to log 14.5 (a rapid one of 0.4 to 10 minutes in duration and a slow one of 2 to 60 minutes).