SURFACTANT-OIL-WATER SYSTEMS NEAR THE AFFINITY INVERSION .8. OPTIMUM FORMULATION AND PHASE-BEHAVIOR OF MIXED ANIONIC-NONIONIC SYSTEMS VERSUS TEMPERATURE

Surfactant-oil-water systems with a phase behavior insensitive to temperature and composition can be achieved by anionic-nonionic mixing. By using of a linear mixing rule and a linear temperature dependency, it is possible to interpret most of the features exhibited by the experimental phase behavior data obtained with sulfonate and ethoxylated alkylphenol mixtures. Deviation from the theoretical model are probably due to anionic and nonionic groups association which reduces the overall hydrophilic character.