The effect of concentration on the viscosity of polyisobutylene solutions

In the past twenty years the viscosity of dilute polymer solutions (i.e., where the solute molecules are far apart) has been investigated in great detail, both theoretically and experimentally. The viscosity characteristics of such systems are well-understood. Only a few studies have been made of the effect of concentration on the viscosity of polymer solutions in the concentration range where the polymer molecules begin to overlap. This range of concentrations is important in practical applications such as dry spinning of fibers, cross-graded automotive motor oils and in many industrial formulations where polymers are used to thicken solvent vehicles. Development of correlations for predicting viscosities in this concentration range from dilute solution measurements (intrinsic viscosities) is needed. It was the purpose of this investigation to obtain accurate viscosity-concentration data in the dilute and in the moderately concentrated range in polyisobutylene solutions in order to correlate these measurements and the literature data on other polymer-solvent systems with concentration and intrinsic viscosity. The effects of the nature of the solvent and polymer molecular weight were studied along with the effect of concentration --Introduction, page 2