EFFECT OF NACL ON A NONIONIC SURFACTANT MICROEMULSION SYSTEM

Various types of microstructure and macroscopic phase changes of the pseudoternary system alkane/Brij 35 + propanol/water, studied in presence of different amounts of sodium chloride at different temperatures, are presented and discussed in this paper. Viscosity and conductance studies reveal that the system at 80% surfactant (S), where S indicates BriJ 35 and 1-propanol together, probably exists as a bicontinuous microemulsion at all water fractions even in the presence of NaCl. In the presence of NaCl, Pseudoternary phase diagrams of the system changes with change of temperature. Increase of the concentration of NaCl brings down the Winsor I --> III transition temperature and at 2.5 M NaCl the system exists as Winsor III along the entire range of temperature studied (30-70 degrees C). However a Winsor III --> II transition was not observed in this case in this temperature range and also within the NaCl concentration range studied. The cloud point of the microemulsions and the contact angle of these systems with a Teflon surface were also determined and discussed. The contact angle values indicate similar structure over the whole range of the oil/water ratio.