Disentangling density and temperature effects in the viscous slowing down of glassforming liquids.
We present a consistent picture of the respective role of density (rho) and temperature (T) in the viscous slowing down of glassforming liquids and polymers. Specifically, based in part upon a new analysis of simulation and experimental data on liquid ortho-terphenyl, we conclude that a zeroth-order description of the approach to the glass transition (in the range of experimentally accessible pressures) should be formulated in terms of a temperature-driven super-Arrhenius activated behavior rather than a density-driven congestion or jamming phenomenon. The density plays a role at a quantitative level, but its effect on the viscosity and the alpha-relaxation time can be simply described via a single parameter, an effective interaction energy that is characteristic of the high-T liquid regime; as a result, rho does not affect the "fragility" of the glassforming system.
Tarjus
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Laboratoire de Physique Theorique des Liquides, Universite Pierre et Marie Curie, 4 place Jussieu, Paris 75005, France.
Kivelson
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D
Mossa
S
S
Alba-Simionesco
C
C