Delayed Elasticity in Inorganic Glasses

The kinetics of the delayed elasticity in inorganic glasses is explained by a molecular rearrangement mechanism with a distribution of activation energies. An experimental method is described by means of which the spectrum of activation energies for the recovery creep process can be determined. Two such spectra, for a soda-lime-silica glass, and for fused silica are presented. The distributions are strongly skewed toward the high-energy side with peaks at 61 and 42.5 kcal/mole for these two glasses, respectively. In soda-lime-silica the rearranging regions are of ionic size, while in fused silica they contain a large number of ions.