FLOW BEHAVIOR OF POLYSTYRENE SYSTEMS IN STEADY SHEARING FLOW

Viscosity and normal stresses have been measured on concentrated solutions of polystyrene in steady shearing flow. The polymers were linear and represented a variety of molecular weight distributions. Master curves of viscosity vs. shear rate were calculated from the distribution with a recently proposed theory and were found to be in good agreement with the experimental curves. Time constants were deduced independently from the viscosity and normal stress behavior of each solution. Each time constant closely paralleled the Rouse relaxation time of the solution, but contained a simple dependence on entanglement density as well. Accordingly, the molecular weight and concentration shift factors for viscoelastic properties in the terminal region depend on entanglement density. At low entanglement densities the factor is ηoM/cT, while at high entanglement densities it becomes η0/c2T. © 1969, American Chemical Society. All rights reserved.