Viscous liquid

The temperature is indicated for industrial soda lime glass: [1] In a widespread classification, due to chemist Austen Angell, a glass-forming liquid is called strong if its viscosity approximately obeys an Arrhenius law (log η is linear in 1/T ).

Viscous flow in amorphous materials is characterised by deviations from the Arrhenius-type behaviour: the activation energy of viscosity Q changes from a high value QH at low temperatures (in the glassy state) to a low value QL at high temperatures (in the liquid state).

Amorphous materials are classified accordingly to the deviation from Arrhenius type behaviour of their viscosities as either strong when QH-QL

[5] The microscopic dynamics at low to moderate viscosities is addressed by a mode-coupling theory, developed by Wolfgang Götze and collaborators since the 1980s.

This theory describes a slowing down of structural relaxation on cooling towards a critical temperature Tc, typically located 20% above Tg.