IONIC SURFACTANT INFLUENCE OVER THE PHASE-BEHAVIOR OF A NONIONIC SURFACTANT BASED SYSTEM

Addition of a small amount of ionic surfactant, as SDS, to a non ionic surfactant based system stabilizes tile water rich region, thus it ca n improve the water-decan co-solubilization. The system becoming more stable with respect to temperature, the Phase Inversion Temperature is shifted towards higher temperatures. The structural study of the syst em : water/(C12EO6 + 1,5 % SDS)/decan shows that the crystal phases ar e lamellar, cubic and direct hexagonal structures at 30 degrees C. The ir structural parameters are determined by small angle X-ray scatterin g. The study of different regions allows tile description of the evolu tion of the surfactant chains conformation.