Interfacial Rheology of Mixed Surfactants at the Oil/Water Interface

The interfacial rheology of surfactant mixtures (SBT and Tween(A (R)) 80) at the oil/water interface is investigated using toluene as a model oil. The surfactant ratio in the mixed system has an important impact on the interfacial properties. After adding Tween(A (R)) 80, the interfacial tension and modulus of SBT show remarkable changes. Compared with the individual SBT or Tween(A (R)) 80 systems, the interfacial properties of the mixed surfactant system improve, especially at a 1:1 ratio. At the optimum ratio, synergistic adsorption takes place resulting in improved asphalt emulsion stability.