PHASE-SEPARATION UNDER A TEMPERATURE-GRADIENT

In the binary systems nitrobenzene-hexane (upper consolute critical te mperature) and triethylamine-water (lower consolute critical temperatu re), maintained in thermal nonequilibrium conditions, the sufficient c ondition to observe two phases is the existence of a temperature corre sponding locally to a two-phase system in equilibrium conditions. The average compositions are almost unchanged under thermal constraint and strong convective motions are reported, with no Marangoni effect at t he liquid-liquid interface.