Effect of die surface on the onset of stick-slip transition in the flow of molten linear polymers

► We model the critical shear stress of the stick-slip instability. ► The critical shear stress is based on work of adhesion and contact angle. ► The model takes into account the molecular weight and the polymer/wall interactions. ► The model describes the effect of die wall roughness. We develop a...

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Bibliographic Details
Published in:Journal of non-Newtonian fluid mechanics 2012, Vol.167, p.46-49
Main Authors: Allal, A., Vergnes, B.
Format: Article
Language:English
Subjects:
Engineering Sciences
Flow instabilities
Materials
Mathematical models
Molecular chains
Polymer melt
Polymers
Shear stress
Slip
Stick-slip
Surface effect
Surface roughness
Wall slip
Walls
Wettability
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Summary:► We model the critical shear stress of the stick-slip instability. ► The critical shear stress is based on work of adhesion and contact angle. ► The model takes into account the molecular weight and the polymer/wall interactions. ► The model describes the effect of die wall roughness. We develop a relationship to describe the effect of surface roughness on the stick-slip transition for linear polymers. Using the Brochard–de Gennes slip model and including molecular chain dynamics at the wall, we develop an expression for the critical shear stress for the onset of wall slip as a function of the wettability of the polymer on the die surface or, more precisely, as a function of the apparent contact angle between polymer and die surface. The surface roughness can be also accounted for using additional parameters.
ISSN:0377-0257
1873-2631
DOI:10.1016/j.jnnfm.2011.10.002