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- Title
Shear-thickening behaviour of concentrated polymer dispersions under steady and oscillatory shear.
- Authors
Li Chang; Friedrich, Klaus; Schlarb, Alois K.; Tanner, Roger; Lin Ye
- Abstract
The rheological behaviour of a 58 vol.% dispersion of styrene/acrylate particles in ethylene glycol was investigated using a plate-on-plate rheometer. Experimental results showed that the concentrated polymer dispersion exhibited a strong shear-thickening transition under both steady shear and dynamic oscillatory conditions. The low-frequency dynamic oscillatory behaviour could be reasonably interpreted in terms of the steady shear behaviour. Accordingly, the critical dynamic shear rate $$ \dot{\gamma }_{{{\text{c\_d}}}} , $$ agreed well with the critical shear rate obtained in steady flow $$ \dot{\gamma }_{{{\text{c\_s}}}} , $$ where $$ \dot{\gamma }_{{{\text{c\_d}}}} $$ was calculated as the maximum shear rate by the critical dynamic shear strain γ and the frequency ω, i.e. $$ \dot{\gamma }_{{{\text{c\_d}}}} = \omega \gamma_{\text{c}} . $$ However, during high-frequency dynamic oscillation, it was observed that the shear thickening occurred only when an apparent critical shear strain was reached, which could not be fully explained by the wall-slipping effect. Based on freeze fracture microscopic observations, the effect of the micro-sized flocculation of particles on the rheology of concentrated dispersions was also discussed.
- Subjects
SHEAR (Mechanics); DISPERSION (Chemistry); STYRENE; ACRYLATES; ETHYLENE glycol; RHEOMETERS
- Publication
Journal of Materials Science, 2011, Vol 46, Issue 2, p339
- ISSN
0022-2461
- Publication type
Article
- DOI
10.1007/s10853-010-4817-5