Rheological behaviour of BSA-cellulose derivative mixtures in neutral aqueous mediumv10iu 6

The rheological behaviour of systems containing both bovine serum albumin and cellulose derivatives (carboxymethylcellulose and hydroxyethylcellulose) in aqueous medium was studied at 25 degrees C, pH 7.0 and 0.1 M (NaCl) ionic strength by viscometry and a stress relaxation method. In comparison with the cellulose derivatives in solution, changes in the rheological behaviour were found to occur with the existence of an apparent yield stress and noticeable viscoelastic properties. These modifications were ascribed to the transition of the system from a solution to a dispersion, the phase separation being due to volume exclusion phenomena between dissimilar macromolecules, although this phase separation cannot be observed directly owing to the high viscosity of the dispersing medium.