IMPROVED CORRELATION FOR SHEAR-DEPENDENT VISCOSITY OF POLYELECTROLYTESOLUTIONS

The reduced-variable approach developed by Graessley has been widely u sed for representing shear-dependent viscosities of organic solutions. However, this method is inadequate for describing charged polymeric s ystems such as polyelectrolytes. Thus a modified reduced approach was developed. The method incorporates the empirical equation of Fuoss and Strauss to account for the strong repulsions between charged groups. It was successfully used to correlate shear-dependent viscosity of pol yelectrolytes in aqueous solutions. Six different polymeric systems we re examined; namely polyacrylamides (Separan AP30, NP10, AP302; Dow Ch emicals), polyethylene oxide (Polyox Coagulant; Union Carbide), carbox ymethylcellulose (CMC; Hercules), and xanthan gum (Keltrol; Kelco). Th e polymer concentrations used range from 10 to 40 000 ppm, covering th e dilute, semidilute and concentrated regimes. The above method has gr eat practical utility as its usage leads to a significant reduction in the experimental work needed to characterize a polymer solution.