Viscosity of glasses below glass transition temperature

摘要

Viscosities of lead-silicate and alkali-silicate glass fibers with a diameter about 100μm were analyzed below glass transition temperature using the fiber-bending method. The curvature radius of bent fiber was measured and the remained strain and stress were evaluated, and then the viscosity was calculated. It was found that below glass transition temperature, the viscosities of these glass fibers increase rapidly with time and then gradually approaching the equilibrium value. Moreover, it was found that above and below glass transition temperature the viscosity obeys Fulcher and Arrhenius equation, respectively. The activation energy above glass transition temperature for the same glass is larger than that below glass transition temperature. On the other hand, it was found that lead oxide and lithium oxide have different effects on viscous flow.