On the rheology of Pluronic F127 aqueous solutions

The rheology of aqueous solutions of Pluronic F127 is studied as a function of concentration, temperature, and shear rate. At sufficiently low temperatures, the solutions behave like Newtonian fluids; a simple empirical model is proposed for the viscosity as a function of temperature and concentration. The solutions undergo a transition to a gel at higher temperature, above which a complex rheological behavior is observed. In this regime, the solutions are viscoplastic with a yield stress that can be as large as hundreds of Pascal. We provide Herschel-Bulkley fits to the rheology for a range of temperatures above the gel point. At much higher temperatures, the rheology of the solutions becomes unsteady and difficult to characterize in terms of a steady-state flow curve. (C) 2016 The Society of Rheology.