Ceramics-Silikáty 21, (4) 291 - 305 (1977)

The free volume theory indicates that during viscous flow the glass melt moves as a whole, and that on the basis of results obtained in the present study no smaller independent flow units should be considered. Dynamic viscosity of glass depends on the number of activated bonds in 1 cm³ regardless of the type of alkaline ion that has caused the activation. The paper further deals with the possibility of calculating the free enthalpy of activated bonds in binary alkali-silicate glasses.