Longest Relaxation Times of Linear Polymers in Concentration Regions between the Critical Concentrations for Zero-Shear Viscosity and for Steady-State Compliance

The longest relaxation times rm of linear polymers in concentration regions between the critical concentrations for the zero-shear viscosity η° and for the steady-state compliance Je, that is, in a semidilute region for η° and in a dilute (not entangled) region for Je, were studied by measuring the stress relaxation after cessation of steady shear flow. It is concluded that the weight-average relaxation time ϊw (= η° Je) is well represented by rm and the magnitudes of the contribution of the terminal relaxation processes to η° are the same in semidilute solutions for η°, whether the entanglements are effective to Je or not.