POLYELECTROLYTE AND RHEOLOGICAL STUDIES ON THE POLYSACCHARIDE WELAN

This paper investigates the polyelectrolyte behaviour of welan in aqueous solution. From conductivity and activity measurements it is demonstrated that a double-helical conformation is adopted irrespective of pH and ionic strength. The intrinsic pK of its carboxylic groups is found to be abnormally low (pK0 2.2) and no conformational transition was observed during neutralization. The viscometric behaviour was studied as a function of degree of neutralization, polymer concentration, shear rate and ionic strength. The linear relation [η]=f(Cs- 1 2) allows the determination of B, the stiffness parameter from Smidsrod, whose value characterizes a very stiff molecule. © 1990.