Rolling-up of triolein and oleic acid with the increase of temperature were investigated to study the detergency of oily soils by using SLS, DBS and NPPG-lOEO as surfactants. Interfacial tensions of triolein/aqueous surfactant solutions and those of oleic acid/aqueous surfactant solutions were measured. Contact angles of triolein and those of oleic acid on PET film and nylon 6 film were measured. Work of detergency of triolein and that of oleic acid were obtained from the interfacial tension and contact angle measurements. Also % removal of triolein and oleic acid was estimated by liquid scintillation counting and the results were as follows: 1. Interfacial tension of triolein/aqueous surfactant solution was the lowest for aqueous NPPG solution, but that of oleic acid/aqueous surfactant solution was lowest for aqueous SLS and DBS solution. Interfacial tension of triolein or oleic acid/water decreased, but that of triolein or oleic acid/aqueous surfactant solution increased as temperature increased. 2. Contact angle of triolein was the largest in aqueous NPPG solution, but that of oleic acid was the largest in aqueous SLS and DBS solution. They increased as temperature increased. 3. It was appeared that work of detergency of triolein was the smallest in aqueous NPPG solution, but that of oleic acid was the smallest in aqueous SLS and DBS solution. Work of detergency of triolein in all of the three aqueous surfactant solutions decreased as temperature increased. Work of detergency of oleic acid in aqueous SLS and DBS solution decreased as temperature increased. 4. Removal of triolein and oleic acid was appeared to be the highest in aqueous NPPG solution and it increased as temperature increased.
