Low frequency storage and loss moduli of soda-silica glasses in the transformation range

The storage and loss moduli of sodium silicate glasses in the transformation range are presented. The data cover the frequency range from 10^?3 to 1 rad/sec. Using linear viscoelastic theory, the frequency-temperature dependence is separated into master curves for the storage and loss moduli at the glass transition temperature and shift factor data describing the shift of the curves with temperature along the frequency scale. These binary glasses are concluded to be thermorheologically simple. The relationship between the shape of the master curves and the configurational entropy is shown, and various available theories for the shift factor data are discussed.