The Effect of CaO and MgO on Physical Properties of MgO-CaO-B2O3-Al2O3-SiO2 Glasses with Composition Close to the E-Glass Fibers

High temperature viscosity and density of glass melts, glass transition temperature, and thermal expansion coefficient of glasses from the system MgO-CaO-B2O3-Al2O3-SiO2 with composition close to the E-glass were measured and interpreted with respect to the effect of CaO and MgO content on their physical properties. The Andrade model was applied for description of the temperature dependence of the glass viscosity within studied temperature range. The regression formaulae describing the compositional dependence of the viscosity points T2 = T( η = 100 dPa.s), T3 = T( η = 1000 dPa.s), the glass transition temperature, Tg, thermal expansion coefficient of glass, αg , and of the viscous flow activation energy, Ea, were proposed.