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Polymer blends in a contraction-expansion flow

Clarke, N.; De Luca, E.; Bent, J.; Buxton, G.A.; Gough, T.; Grillo, I.; Hutchings, L.R.

Authors

N. Clarke

E. De Luca

J. Bent

G.A. Buxton

T. Gough

I. Grillo



Abstract

We have probed the coupling between flow and concentration fluctuations in polymer blends using small-angle neutron scattering. We utilized a recirculating cell with a slot die, enabling us to measure the behavior at the entrance, within and at the exit of a contraction-expansion flow. While, as expected, anisotropy was observed in all nonquiescent experiments, the correlation lengths associated with the concentration fluctuations are found to be "stretched" more in the direction perpendicular to the flow at all positions along the centerline of the flow, except at the slot die exit. To gain insight into the observations, we present calculations of the scattering based on a multiscale approach, which bridges the gap between macroscopic Newtonian fluid dynamics and the convection of nanoscale concentration fluctuations. However, we find that this model contains insufficient physics to correctly describe our observations. Consequently, we argue that the deformation of the correlation length is primarily due to the coupling between weakly non-Newtonian stresses and thermodynamics.

Citation

Clarke, N., De Luca, E., Bent, J., Buxton, G., Gough, T., Grillo, I., & Hutchings, L. (2006). Polymer blends in a contraction-expansion flow. Macromolecules, 39(22), 7607-7616. https://doi.org/10.1021/ma0610966

Journal Article Type Article
Publication Date Oct 1, 2006
Deposit Date May 11, 2007
Journal Macromolecules
Print ISSN 0024-9297
Electronic ISSN 1520-5835
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 39
Issue 22
Pages 7607-7616
DOI https://doi.org/10.1021/ma0610966