DELAYED ELASTICITY AND VISCOSITY OF SILICATE-GLASSES BELOW THE GLASS-TRANSITION TEMPERATURE

The viscosity of pre-annealed lead-silicate glass was studied below th e glass transition temperature using the fiber-bending method. The vis cosities were determined under conditions of loading and unloading. Th e delayed elasticity and its effect on the viscosity were also investi gated. In the case of equal loading and unloading times, the viscosity was the same for the loading and unloading processes and the delayed elasticity was larger within shorter periods and smaller for longer on es. In addition, the time necessary for the recovery of the delayed el asticity increases with increasing loading time.