ISSN:
1435-1536
Schlagwort(e):
Critical point scaling laws
;
interfacial tension
;
liquid-liquid interfaces
;
nonionic surfactants
;
oil-water-surfactant systems
;
three-phase systems
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
Notizen:
Abstract Measurements are reported of the interfacial tension in two-phase ternary systems of water(1) + hydrocarbon(2) + 2-butoxyethanol(3) atT=25°C along a linear path to the critical point (plait point). The two systems studied (with heptane and octane as the hydrocarbon component) exhibit a three-phase region and differ in respect of the distance of the upper critical end pointT u of this three-phase region from the experimental temperature (T〉T u). Along the chosen linear path, a stepwise decrease of the tensionσ with increasing concentration of the amphiphile,ω 3, is found: in region (i)σ decreases from its initial value (50 mN m−1) to about 2 mN m−1 due to the adsorption of the amphiphile; in region (ii) which extends over a wide composition range of the upper phase,σ exhibits an inflection point and is only a weak function ofw 3; on approaching the critical point there is a second inflection point inσ vs.w 3 and finally, in a rather narrow range of concentration (w 3 c -w 3), a follows the asymptotic critical-point scaling (region iii). In region (ii), the interfacial tension of the octane system (for whichT-T u is only about 1 K) falls below that of the heptane system and remains nearly constant, as expected for systems near three-phase coexistence.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01452591
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