Modification of the rheological behaviour of sodium alginate by chitosan and multivalent electrolytes

The rheological behaviour of sodium alginate/chitosan blends was examined at several mixture ratios. While both polymers exhibited nearly the same viscosity at low concentrations (1.0 and 2.0 w%), chitosan solutions had higher viscosity and greater deviation from Newtonian behaviour at high solution concentrations (3.0-5.0 w%). The viscosity of alginate/chitosan mixtures was substantially increased. Blends containing predominantly one component were of higher viscosity than blends with approximately equal proportions of both polymers. The viscosity of alginate solutions was strongly affected by the addition of electrolytes, with Ba[Cl.sub.2] exerting the greatest effect on the alginate viscosity and shear thinning behaviour. --Keywords: alginate, chitosan, electrolyte, rheology, shear thinning-