Adams and Olmsted Reply to comment on article "A non-monotonic constitutive model is not necessary to obtain shear banding phenomena in entangled polymer solution" [Phys. Rev. Lett. 102, 067801 (2009), arXiv:0805.0679]

TL;DR

This paper is a reply clarifying misconceptions about shear banding in entangled polymer solutions, emphasizing that non-monotonic models are not necessary to explain shear banding phenomena, and addressing experimental and parameter disagreements.

Contribution

The authors defend their original claim that shear banding can occur without non-monotonic constitutive models, countering critiques about stress gradients and experimental interpretations.

Findings

Shear banding can occur without non-monotonic flow curves.

Experimental observations of shear banding do not always require stress gradients.

Parameter disagreements do not invalidate the original model.

Abstract

Wang [Phys. Rev. Lett. 103, 219801 (2009)] makes the following points about our Letter [Phys. Rev. Lett. 102, 067801 (2009), arXiv:0805.0679]: (1) He infers that, "contrary to its title, shear banding emerged from monotonic curves only if there was a stress gradient", and he points out that nonquiescent relaxation was found (experimentally) after step strain in geometries without a stress gradient. (2) He disagrees with the values of the parameters we used. (3) In some recent experiments the flow was homogeneous after cessation of step strain, and only subsequently developed nonquiescent macroscopic motion. We only showed step strains that developed an inhomogeneity before cessation of flow. In this reply we address these points.