EFFECT OF SOLUBILIZED DECANOL ON SOME PROPERTIES OF AQUEOUS SODIUM OCTANOATE SOLUTIONS

The influence of decanol solubilization on the viscosity and the water vapor pressure of sodium octanoate solutions has been studied. The incorporation of decanol in the micelles causes an increase in the viscosity as well as in the vapor pressure at all concentrations above the CMC. The increase in viscosity is caused by the increased volume fraction of the micellar substance and is particularly obvious above the 3rd critical concentration, where the amount of hydrated micellar substance is so high that crowding between the micelles occurs. Under some circumstances the viscosity increase is somewhat retarded by the decrease of the charge density in the boundary layers of the micelles caused by the incorporation of decanol. The increase of water vapor pressure is due to the fact that the concentration of octanoate and sodium ions in the intermicellar solution is lower in the decanol-containing system than in the pure octanoate solutions and to the fact that the charge density in the boundary layer of the micelles decreases by the incorporation of decanol. The latter is more significant the higher the micellar concentration. © 1979.