Extensional viscosity of o/w emulsion stabilized by polysaccharides measured on the opposed-nozzle device

The shear and extensional viscosities characteristics of mineral oil-in-water emulsions with dispersed volume fractions varying between 20 vol.% and 40 vol.% have been investigated and compared. The opposed-nozzles configuration was used to measure the extensional viscosity. Four kinds of hydrocolloids were used: xanthan gum (XG), guar gum (GG), hydroxypropylmethylcellulose (HPMC) and carboxymethylcellulose sodium salt (Na-CMC). Presented results of rheological measurements have shown that the extensional viscosity of the o/w emulsion with the addition of hydrocolloids determines the properties of the continuous phase and the structure of dispersed phase. The greatest relative increase between extensional viscosity of the emulsion and extensional viscosity of aqueous polymer solution was observed when the dispersed phase was strongly flocculated. At the same time, the value of the extensional viscosity of the weakly flocculated emulsion has been determined by the rheological properties of the continuous phase when viscoelastic liquid (emulsions with the addition of XG) was under concern. (c) 2012 Elsevier Ltd. All rights reserved.