Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The viscosity and streaming birefringence of fractionated and unfractionated samples of sodium alginate have been measured at various concentrations, and rates of shear, and in the presence and absence of added salt. The viscosity data show the concave upward curve typical of polyelectrolytes at low concentrations, but pass through a minimum at higher concentrations. The influence of shear is least at this minimum. The initial slope of the orientation angle versus velocity gradient curves increases with concentration, but Δn/c is independent of concentration. The semiempirical theory of Peterlin for concentrated solutions is obeyed by the data for Δn, but not by that for the orientation angle. Molecular weights have been calculated from the hydrodynamic parameters. The viscosity behavior is interpreted in terms of the rigidity of the molecule.
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