Effect of edge disturbance on shear banding in polymeric solutions

Seunghwan Shin, Kevin D. Dorfman, Xiang Cheng

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Edge instabilities are believed to be one of the possible causes of shear banding in entangled polymeric fluids. Here, we investigate the effect of edge disturbance on the shear-induced dynamics of well-entangled DNA solutions. Using a custom high-aspect-ratio planar-Couette cell, we systematically measure the velocity profiles of sheared DNA samples at different distances away from the edge of the shear cell. Under a weak oscillatory shear with the corresponding Weissenberg number (Wi) smaller than 1, where DNA solutions exhibit linear velocity profiles with strong wall slip, the penetration depth of the edge disturbance is on the order of the gap thickness of the shear cell, consistent with the behavior of Newtonian fluids. However, under a strong oscillatory shear with Wi >1 that produces shear-banding flows, the penetration depth is an order of magnitude larger than the gap thickness and becomes spatially anisotropic. Moreover, we find that the shear-banding flows persist deep inside the sheared sample, where the effect of edge disturbance diminishes. Hence, our experiments demonstrate an abnormally long penetration depth of edge disturbance and illustrate the bulk nature of shear-banding flows of entangled polymeric fluids under time-dependent oscillatory shear.

Original languageEnglish (US)
Pages (from-to)1339-1345
Number of pages7
JournalJournal of Rheology
Volume62
Issue number6
DOIs
StatePublished - Nov 1 2018

Bibliographical note

Funding Information:
The authors thank Suzanne Fielding for comments on an early version of this manuscript. This work was supported by NSF Grant No. CBET-1700771.

Fingerprint Dive into the research topics of 'Effect of edge disturbance on shear banding in polymeric solutions'. Together they form a unique fingerprint.

Cite this