T. A. Dyakina, S. R. Derkatch, S. M. Levachev Concentrated Gelatin/Lecithin Emulsions: Rheological Properties Abstract Rheological properties of the concentrated heptane-in-water emulsions (content of dispersed phase j = 0.64 ¸ 0.80%) have been investigated. The aqueous phase contains biopolymer (gelatin) and natural phospholipid lecithin. Using the method of rotational (with controlled shear rate) viscosimetry it has been shown that the concentrated emulsions reveal the properties of visco-plastic material under shear deformation. The rheological behavior of emulsions within the non-linear viscous range is concerned with Hershel-Bulkley model and Casson model. Addition of phospholipid in the system being accompanied by its association with gelatin leads to the decrease of yield stress and the increase of plastic viscosity in comparison with the concentrated emulsions of gelatin. Values of the rheological parameters change droningly under the increase of lecithin concentration. Quantitative assessment of the individual contact strength between the drops covered with the adsorption layers of gelatin-phospholipid complexes has been carried out.
Copyright (C) Chemistry Dept., Moscow State University, 2002 |
|