Diffusion-viscosity decoupling in supercooled glycerol aqueous solutions

JOSÉ A TREJO GONZÁLEZ; MA. PAULA LONGINOTTI; HORACIO R. CORTI

JOURNAL OF PHYSICAL CHEMISTRY B

American Chemical Society

Año: 2015 vol. 119 p. 257 - 262

1089-5647

The diffusion of ferrocene methanol in supercooled glycerol-water mixtures has been measured over a wide viscosity range, which allowed analyzing the composition dependence of the Stokes-Einstein breakdown (diffusion-viscosity decoupling). The observed decoupling exhibits a common behavior for all studied compositions (glycerol mass fractions between 0.7 and 0.9), determined by the reduced temperature (T/Tg) of the mixtures. This result differs from that reported previously for the diffusion of glycerol in its aqueous solutions, where the reduced temperature for the decoupling decreases with increasing water content. We conclude that the contradictory results are only apparent, and they can be explained by the use of inconsistent  extrapolated values of the viscosity of the glycerol-water mixtures in the supercooled region.