Abstract
The effects of the added salt concentration and added salt species on the rheological properties of gellan aqueous solutions in the dilute regime were investigated in terms of the steady shear and dynamic viscoelasticity measurements. The zero-shear viscosity (η0) obtained from those measurements indicated that the chain conformation in random-coil state became more compact with increasing salt concentration in the solution due to the shielding effect of the ions from the salt, but the conformation was independent of the salt species added, suggesting that the chain conformation was dominated by the ionic strength. The crossover concentration (cc) for η0· was estimated. The value of cc, increased with increasing salt concentration due to the change in conformation of the polymer chains. The mean-square radius of gyration of the polymer chains were calculated from η 0 and the dependence of the radius on cs, was discussed.
