| Measurements of low and ultralow interfacial tension, (gamma)(,i), ranging from 0.3 to 3 mN/M, on water/toluene interfaces containing various amount of 1-propanol and from 10('-1) to 10('-3) mN/M on toluene/SDS/ 1-butanol/Saline NaCl interfaces containing various concentration of NaCl has been undertaken with laser light scattering, spinning drop, pendant drop and Wilhelmy blade methods. The instrument contribution to the spectrum obtained from the laser light scattering method was found to be represented by a Lorentzian-squared function. The interfacial viscosity is then calculated from the spectral linewidth using this instrumental function and compared to the bulk viscosity. Measurements of phase volume and interfacial tension on water/toluene/1-propanol systems indicate that a requirement for formation of O/W dispersion is low (gamma)(,i), but for overall stability, (gamma)(,i), although small, must be positive. From extrapolation of the measured (gamma)(,i) values on water/toluene/1-propanol systems, it has been found that a residual positive value of 0.2 mN/M is still observed at cosolubilization. |
