Experimental evidence of the critical phenomenon and shear banding flow in polymer-like micellar solutions

Abstract

Steady shear and rheo-optical experimental data measured in several micellar solutions, demonstrate the existence of a non-equilibrium critical point (necp) in the shear banding flow of wormlike micellar solutions by the following evidence: (1) the disappearance of the coexistence of two steady banded fluids at the necp, (2) the curves of the reduced shear stress versus reduced shear rate become anti-symmetric in the neighborhood of the non-equilibrium critical point; (3) flow birefringence increases considerably in the neighborhood of the necp; (4) the divergence of non-equilibrium thermodynamic properties (isothermal flow susceptibility and the normalized heat dissipation), as the necp is approached; and (5) the existence of a finite correlation dimension calculated from time analysis of birefringence data, and positive Lyapunov exponents, which are consistently smaller than the embedding dimension.The predictions of the BMP model follow these trends closely. © 2012 .