Badiger, M., Gupta, N.R., Eckelt, J., Wolf, B.A.

"Intrinsic viscosity of aqueous solutions of Carboxymethyl Guar in the presence and absence of salt"

Macromolecular Chemistry and Physics 2008, 209, 2087-2093.

Abstract: Intrinsic viscosities, [h ], were determined for solutions of carboxymethyl guar (CMG, M w = 860 kg/mol, degree of substitution = 0.15) in pure water and in water containing 0.9 wt% NaCl. For the evaluation of the primary data obtained from capillary viscometry we have used a new procedure (plots of ln h rel versus polymer concentration c) that avoids an extrapolation of the zero-divided-by-zero type, which is typical for Huggins plots. For CMG and pure water this dependence requires two adjustable parameters for its quantitative modeling: [h ] (the specific hydrodynamic volume of the polymer in the limit of infinite dilution) and a hydrodynamic interaction parameter. A third parameter (another specific hydrodynamic volume, characterizing the viscometric behavior in the range of high polymer concentrations), as in the case of solutions of Na-polystyrene sulfonate (Na-PSS), is not needed. The intrinsic viscosity of CMG (no salt) at room temperature is 6 050 mL/g; this value is approximately only half as large as that of Na-PSS of comparable molar mass. The ratio of the intrinsic viscosities in the absence and in the presence of salt is for CMG roughly seven, in relation to a factor of more than one hundred observed for Na-PSS. The reasons for the unlike behavior of the two types of polyelectrolytes are being discussed.

preprint number: 291