Heat Of Annealing In Somple Alkali Silicate Glasses

The enthalpy changes associated with annealing of glass were studied in simple and mixed alkali silicate glasses. The data indicate that during prolonged annealing the glass comes to a metastable equilibrium state and has a unique heat of solution which depends on its fictive temperature. The heats of solution of these glasses show a linear dependence on fictive temperature and the magnitude of the dependence is related to the molar volume of the glass. The significance of these heat effects is discussed.