Shear dependence of the viscosities of both nitroethane-3-methylpentane and polystyrene-cyclohexane mixtures in the critical region

The shear viscosities of a critical mixture of nitroethane-3-methylpentane were measured near the critical temperature (ΔT values of 0.500 to 0.55°C) over a range of shear rates from 700 to 0.015 sec−1. No shear dependence within experimental error was found at any temperature. The shear viscosities of solutions of polystyrene-cyclohexane near or at the critical composition were also measured at shear rates from 1500 to 0.1 sec−1 and at a ΔT value of 0.24°C. A constant 10% increase in viscosity at low shear was found for mixtures having concentrations near the critical concentration. Consequently the increase cannot be solely attributed to critical phenomena, but must be related to other polymeric phenomena.