Rheological properties of sodium alginate solutions in the presence of added salt: an application of Kulicke equation

Abstract

Mark–Houwink parameters are determined for sodium alginate with low (SA LV) and medium (SA MV) molecular mass via a rheological approach. Firstly, salt screening concentration and polyelectrolyte nature of the polymers are investigated. Despite both alginates behaving as neutral polymer in θ solvent, differences are observed between them with the strong associative nature of SA MV highlighted by an abnormal high viscosity concentration dependence compared with the predicted values. The polysaccharide-specific hydrodynamic volume (i.e., intrinsic viscosity) is determined via Fedors approach, which is proved to provide accurate results applicable to a wide concentration range. A viscosity–molecular mass–concentration relationship is finally derived to calculate Mark–Houwink parameters via a non-linear regression according to Kulicke equation; the obtained values are consistent with those reported in literature, confirming the semi-flexible nature of SA in the investigated environment and proving the effectiveness of the proposed approach for polyelectrolytes with added salt ions.