We carry out a systematic investigation into steady-state shear behavior of six entangled solutions based on a superposition of continuous shear and small amplitude oscillatory shear (SAOS). During steady shear in the shear thinning regime, the superimposed SAOS frequency sweep measurements reveal characteristics of viscous liquids, e. g., terminal dynamics, on the experimental time scale of the reciprocal shear rate. The residual entanglement network retains the same level of elastic stiffness as the equilibrium system does. Consistent with the convective constraint release idea, chains in the network are forced to pass around each other as they must do so to undergo steady flow. When such a sample is examined at significantly short time scales, chains are unable to pass around and the signature of this residual entanglement is that the storage modulus is greater than the loss modulus at higher frequencies than the applied shear rate. The particle-tracking velocimetric observations confirm that whether shear banding is present or not does not affect the basic "terminal flow" character revealed by the superimposed SAOS. (C) 2009 The Society of Rheology. [DOI: 10.1122/1.3236523]
Journal of Rheology
Required Publisher's Statement
Copyright 2009 American Institute of Physics. The original published version of this article may be found at http://dx.doi.org/10.1122/1.3236523.
Boukany, Pouyan E. and Wang, Shi-Qing, "Nature of Steady Flow in Entangled Fluids Revealed by Superimposed Small Amplitude Oscillatory Shear" (2009). College of Polymer Science and Polymer Engineering. 99.