Rheological studies of moderately concentrated polystyrene solutions. I. A new method for the extrapolation of the zero-shear viscosity

Measurements of the viscosity coefficient η of solutions of polystyrene (M_w = 6.0 × 10⁵ and 1.77 × 10⁶) in trans-decalin (TD, θ solvent) and toluene (TL, good solvent) as function of shear rate (11?10⁴ s^?1), concentration (4.24?11.21 wt %), and temperature (10–50°C) are reported. As a new theoretically grounded method for the determination of the zero-shear viscosity η₀ it is proposed to plot η as a function of $left({eta dot gamma} right)^3$. The intercepts of the straight lines obtained by this procedure give η₀ in good agreement with directly measured values.