Morphology and shear viscosity of aqueous two-phase biopolymer-surfactant mixtures

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  • Unilever
  • University of Nottingham


The relation between composition, rheology, and morphology in phase separated pullulan-sodium dodecyl sulphate systems containing sodium chloride has been investigated using rheo-optical methods. The rheological measurements showed that the apparent viscosity of these aqueous two-phase systems depends on the chemical composition of each phase, their volumetric composition, and the viscosity ratio of the separated phases. Optical observations revealed a droplet like morphology over a wide range of shear rates at low to moderate volume fractions of pullulan-rich phase. In some mixtures, string phases were observed at higher volume fractions of pullulan-rich phase and shear rates. Simultaneous analysis of the rheological data and observed structures at different shear rates/compositions indicates a close link between rheology and morphology of aqueous two-phase systems and provides a simple tool for predicting morphology on the basis of rheological data.


Original languageEnglish
Pages (from-to)867-881
Number of pages15
JournalJournal of Rheology
Issue number5
Publication statusPublished - 27 Aug 2007


  • Aqueous two-phase systems, Co-continuity, Pullulan, Rheology, SDS