Rheology of concentrated poly(ethylene oxide) solutions

This paper reports on the rheological properties of a series of concentrated poly(ethylene oxide) solutions. The polymers were obtained from two sources and dissolved in two solvents. Data on viscosity, primary normal stress differences, and dynamic rigidity were obtained using two Weissenberg rheogoniometers, a Rheometrics stress rheometer and a Bohlin VOR instrument. All the viscosity and normal stress data could be correlated using two key parameters: the zero shear viscosity and a characteristic time constant. Master curves are obtained which are almost independent of concentration, solvent, and molecular weight. The Cox–Merz rule is found to be valid for all solutions; however, the analogy between the primary normal stress coefficient and the storage modulus is verified only at low shear rates or frequencies. In addition, a modified rheological model based on the conformation tensor is shown to well represent the shear data.