Interfacial Rheology of Mixed Surfactants at the Oil/Water Interface

The interfacial rheology of surfactant mixtures (SBT and Tween ® 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 ® 80, the interfacial tension and modulus of SBT show remarkable changes. Compared with the individual SBT or Tween ® 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.