PERCOLATION PHENOMENON IN TERNARY MICROEMULSIONS - THE EFFECT OF PRESSURE

The electrical conductivity sigma and dynamic viscosity eta of water-b ased water-AOT-undecane [AOT:sodium bis(2-ethylhexyl) sulfosuccinate) microemulsions and waterless glycerol-AOT-isooctane microemulsions wer e studied as a function of volume fraction phi in dispersed matter (wa ter plus AOT or glycerol plus AOT) and pressure up to 1000 bar. The re alm of existence of the single-phase zone was also determined versus p ressure P. The curves eta(P) and sigma(P) at constant phi and temperat ure T, and the curves eta(phi) and sigma(phi) at constant P and T were analyzed within the framework of percolation theory. For water-based microemulsions the percolation threshold phi(c) decreases when P incre ases, corresponding to an increase in interactions. For waterless micr oemulsions phi(c) varies very little. The scaling exponents are almost -equal-to 2 above the threshold and almost-equal-to - 1.2 below, whate ver the pressure, the system, and the property studied (values which h ave already between obtained at 1 bar). This corresponds to the fact t hat these systems belong to the same class of universality.