Second, according to Allouche et al.[17] two kinds of
transitions can occur when an emulsified water=oil=ethoxylated nonionic surfactant system is cooled under constant
stirring. At a water=oil ratio close to unity, a transitional
inversion takes place from a water=oil (W=O) to an oil=
water (O=W) morphology according to the so-called phase
inversion-temperature method. The continuous monitoring
of both the emulsion conductivity and viscosity allows
the identification of several phenomena that take place
during the temperature decrease. In all cases, a viscosity
maximum is found on each side of the three-phase
behavior temperature interval and correlates with the
attainment of extremely fine emulsions, where the best
compromise between a low-tension and a not too-unstable
emulsion is reached