Factors Affecting the Phase-Inversion Temperature of Fatty Alcohol Ethoxylates

Factors that affect the phase-inversion temperature (PIT) based on nonionic surfactant fatty alcohol ethoxylates were investigated. Phase-inversion process was continuously monitored by determining changes in conductivity with temperature. The influences of oil-to-water ratio, emulsifier concentration, emulsifier mixing ratio, sodium chloride, and oil types on the PIT of emulsions were investigated. Results showed that the PIT of the emulsions declined with increased oil-to-water ratio. Emulsifier concentration significantly affected the PIT temperature. High sodium chloride content suppressed phase inversion. A lower Brij72-to-Brij721 ratio corresponded to higher PIT. Different oils required different HLB numbers in the phase-inversion process.