A Study of the Elastico- Viscous Properties of a Soda–Lime–Silica Glass at Temperatures near the “Transformation Point”
JSGT 1937 V21 T061-T081
Isothermal creep tests of stabilised fibres of a soda–lime–silica glass have been made in the range 475-525°. Elongation is due to viscous flow at constant rate plus completely reversible elastic distortion, instantaneous and delayed. For the latter, dl/dt=kl, l being the unstretched part at time t. Furthermore, log k=A' /Tabs+constant, where A' =8·05×104. This relation shows no break at the “transformation point,” 515° (from thermal expansion), but above 515° the rates are rapid (large values of k)and the glass acts like an ordinary liquid. Young's modulus, based on the total elastic distortion, appears independent of temperature. The slope of the logη versus 1/Tabscurve for viscous flow is 7·04×104. An ionic picture of the elastic process is given.
Nelson W. Taylor, Edward P. McNamara & Jack Sherman
