Abstract
In this work, we study the origin of the extension thickening commonly observed when solutions of flexible polymers flow through porous media and ideal elongational flows. We have used randomly packed beds of glass beads as porous media. We have performed experiments with closely monodisperse atactic polystyrene of different molecular weights dissolved in organic solvents. The use of a closely monodisperse polymer allowed us to make a more meaningful comparison between the results obtained using opposed jets and porous media flow, as compared to previous works on polydisperse polymers. The results indicate that the coil-stretch transition of isolated polymer molecules in solution cannot be the only mechanism responsible for the extension thickening. It is clear that part of the observed effect is due to the extension of isolated molecules, but the main factor causing a great increase in the elongation viscosity beyond a critical strain rate is the formation of transient entanglement networks.
Original language | English (US) |
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Pages (from-to) | 1224-1233 |
Number of pages | 10 |
Journal | Colloid & Polymer Science |
Volume | 272 |
Issue number | 10 |
DOIs | |
State | Published - Oct 1994 |
Keywords
- Porous media
- elongational flow
- elongational viscosity
- entanglements
- monodisperse polystyrene
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Colloid and Surface Chemistry
- Materials Chemistry