The Effective Hydrophile - Lipoph1le Balance Op Nonionic Surfactant Mixtures

In the phenol index method, forces between water and the hydrophilic groups of the mixed micelles decrease with increasing phenol concentration. This results in a depression of the cloud point with substantial changes in the micellar structure and decrease of the hydrophilic properties of the mixed micelles. The effective HLB of the mixtures of nonionic surfactants is thus also altered and in the case of surfactants differing remarkably in the polyoxyethylene chain length is higher than the calculated ones. Deviation from additivity in HLB values are explained on the basis of hydration change of the polyoxyethylene shell with the change in composition of mixed micelles.