Thermodynamics of viscous flow and elasticity of glass forming liquids in the Transition Range

Par Tanguy Rouxel, Mardi 18 octobre 2011, 10:45-12:15

The elastic moduli of glasses from different chemical systems, including oxide, chalcogenide, oxynitride, and metallic, were investigated through the glass transition, typically from 0.4 to 1.3 Tg. These data were used to interpret the non-Arrhenian temperature sensitivity of the shear viscosity coefficient obtained on the same materials. The relevant Gibbs free activation energy was estimated from the apparent heat of flow by means of the temperature dependence of the shear elastic modulus. The activation entropy associated with the viscous flow was also derived and was found to correlate with the fragile versus strong character of the glass forming liquids. Finally, the physico-chemistry of the flow process is described on the basis of the glass network de-structuration which shows up through the temperature dependence of Poisson’s ratio.

Deux publications associées à cet exposé sont disponibles :
- « Thermodynamics of viscous flow and elasticity of glass forming liquids in the glass transition range », Journal of Chemical Physics 135, 184501 (2011)
- « Poisson’s ratio and modern materials », Nature Materials 10, pp. 823–837 (2011)

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Mis en ligne le samedi 9 juillet 2011