Elastic yielding after step shear and during LAOS in the absence of meniscus failure

Abstract

This work examines the possibility that the previously observed elastic yielding, i.e., nonquiescent relaxation after a large step shear (Ravindranath and Wang, Macromolecules 40:8031–8039, 2007) is due to an intrinsic experimental difficulty technically known as edge fracture. By redesigning the rheometric apparatus to eliminate edge failure, we show by an example of a well-entangled polymer solution that elastic yielding still occurs in the absence of any edge failure. We are also able to confirm that shear banding during large amplitude oscillatory shear (Ravindranath and Wang, J Rheol 52:341–358, 2008a) is an inherent rheological characteristic related to internal yielding of the entanglement network.