Phase equilibrium in complex liquids under negative pressure
Attila R. Imrea, Alexandra Drozd-Rzoskab, Thomas Kraskac, Luis P. Rebelod, Sylwester J.
Rzoskab, W. Alexander Van Hooke, Zoran P. Visakd and Leonid V. Yelashc
a
b
c
KFKI Atomic Energy Research Institute, H-1525 POB 49, Budapest, Hungary
Institute of Physics, Silesian University, ul. Universytecha 4, 40-007, Katowice, Poland
Institut für Physikalische Chemie, Universität zu Köln, Luxemburger Str. 116, D-50939
Köln, Germany,
d
Instituto de Tecnologia Química e Biológica, ITQB2, Universidade Nova de Lisboa,
Apartado 127, 2780-901 Oeiras, Portugal
e
Chemistry Department, University of Tennessee, Knoxville, TN 37996-1600, USA
Liquids under some specific external condition are referred as complex liquids. One of
these specific conditions is the stretching of liquids, where the pressure can be negative
[1,2,3] and the liquid will be extended, i.e. it can reach extremely low densities.
There are several studies, concerning the behaviour of these extended liquids, but only a
very small fraction of them are concerned with the phase equilibrium. Because no gas phase
can exist under negative pressure, these equilibria can be only liquid-liquid or liquid-solid.
In this talk we are going to present experimental and theoretical results concerning liquidliquid equilibrium in liquids under negative pressure. There are three groups of liquids which
have been studied experimentally [3]:
- binary solution of small molecules (methylpyridine/water, methylpyridine/heavy water,
nitrobenzene/alkanes)
- binary polymeric liquids (some polystyrene solutions)
- liquid crystals
The phase diagrams of these systems close to p=0 are usually the smooth expansion of the
positive pressure parts, but at deeper negative pressures sometimes unexpected behaviours
can be seen.
At deep negative pressures the liquids will reach the liquid-vapour instability line (spinodal),
i.e. the liquid-liquid phase diagrams cannot be extended to arbitrarily low values, they have to
be terminated before crossing the spinodal. We are going to present calculations, that in some
binary liquids the liquid-liquid phase diagram will be terminated much earlier than reaching
the instability line [4].
1.
2.
3.
4.
Trevena, D.H.: Cavitation and tension in liquids, Adam Hilger, Bristol, 1987
Debenedetti, P.G.: Metastable liquids: Concepts and principles, Princeton University Press, Princeton, N.J.,
1996
Liquids Under Negative Pressure (Eds.: A.R. Imre, H.J. Maris and P.R. Williams), Kluwer, Dordrecht, 2002
A.R. Imre, A. Drozd-Rzoska, T. Kraska, S. J. Rzoska and L. V. Yelash: Liquids Under Absolute Negative
Pressure, Proceeding Book of the CSSNS, in press