The reduced specific viscosity of fully sulfonated sodium neutralized polystyrene under "free salt" conditions was investigated as a function of temperature. It was found that the position of the maxima is strongly dependent on temperature. Small temperature changes (DELTA-T = 20 K) introduce shifts of two orders of magnitude in the polyelectrolyte concentration at which the maximum appear. At a given temperature C(pmax) is linearly dependent on molecular weight, the slope of the linear plot is temperature dependent increasing with temperature. The value of C(p) at the maximum increases linearly with concentrations of externally added salt at all temperatures and molecular weights. At a given molecular weight, the logarithm of C(pmax) is inversely dependent on temperature. The activation energy was calculated and found to be independent of the molecular weight of the polyelectrolyte. The dependence of the reduced specific viscosity on normalized polyelectrolyte concentration (C(p)/C(pmax) resulted in one "master curve" for all temperatures at a given molecular weight. Below the maximum, at lower polyelectrolyte concentration, a linear dependence of eta-sp/C(p) on C(p) was obtained even for salt-free solutions. The apparent intrinsic viscosity and the Huggins coefficient were calculated, as it is done for noncharged polymers in the linear regime. High values of apparent intrinsic viscosity and the Huggins coefficient were obtained. The high measured values cannot be explained by hydrodynamic contribution of fully stretched molecules, indicating that even at extremely high dilutions the main contribution is the one of long range interactions (Culombic or others). The dependence of the apparent intrinsic viscosity on molecular weight was established. These measurements could be performed thanks to the availability of the apparatus developed by us which makes possible accurate measurements of the shear viscosity of low ionic strength, dilute polyelectrolyte solutions, down to polymer concentrations below one part per million.
