Structural, shear and volume relaxation in a commercial float glass during aging

Density, Raman spectroscopy and viscosity measurements are utilized to probe, respectively, the volume, structural shear relaxation behavior of a Na-Ca-Mg silicate glass standard commercial float composition at ∼80 °C below its calorimetric transition. The results, when taken together, indicate that lowering fictive temperature during aging results in Q-species disproportionation type Q2+Q4→2Q3, all three processes characterized by stretched exponential kinetics with similar average timescale (〈τ〉∼ 300 h) stretching exponent (β ∼ 0.4), implying close mechanistic relationship. It is hypothesized coexistence strongly weakly constrained domains or moieties network supercooled liquid can give rise temporal decoupling between processes, as has been reported some recent studies literature.