Paper Number
SM24 

Session
Polymer Solutions and Melts

Title
Shear banding in entangled polymers in micron scale gap: A confocal-rheoscopic study

Presentation Date and Time
October 7, 2014 (Tuesday) 2:45

Track / Room
Track 3 / Commonwealth C

Authors (Click on name to view author profile)

1. Boukany, Pouyan (Delft University of Technology, Chemical Engineering Department)
2. Wang, Shi-Qing (University of Akron)

Author and Affiliation Lines (in printed abstract book)
Pouyan Boukany¹ and Shi-Qing Wang^2
1Chemical Engineering Department, Delft University of Technology, Delft 2628 BL, The Netherlands; ²University of Akron, Akron, OH

Speaker / Presenter 
Boukany, Pouyan

Text of Abstract
Based on simultaneous rheometric and particle-tracking velocimetric measurements, this work characterizes the deformation fields of two identically entangled polybutadiene (PBD) solutions in a small gap distance of H ~ 50 µm. At a concentration of 13 wt % of PBD with Mw = 1.0 × 10⁶ g/mol, there are 54 entanglements per chain in these solutions. We use two different polymeric butadiene solvents to prepare two 13 % solutions that have different intrinsic capacities to undergo wall slip. For the PBD solution made with a low molecular-weight PBD solvent of 1.5 kg/mol, wall slip is the dominant response within the accessible range of the shear rate, i.e., up to a nominal Weissenberg number Wi as high as 290. Wall slip is minimized in solution made with a high molecular-weight PBD solvent of 10 kg/mol. Severe shear banding is observed in this second solution. These results are consistent with the published phase diagram (Macromolecules 2011, 44, 183) depicting the relation between homogeneous shear, wall slip and shear banding.