Chellamuthu, Manojkumar and Arndt, Eric M. and Rothstein, Jonathan P.. (2009) Extensional rheology of shear-thickening nanoparticle suspensions. Soft Matter, 5 (10). pp. 2117-2124. ISSN 1744-683X
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A filament-stretching rheometer is used to measure the extensional properties of shear-thickening nanoparticle suspensions as a function of concentration and extension rate. The experiments are performed using a series of colloidal suspensions consisting of concentrations of 17.5 wt%, 25 wt% and 30 wt% of fumed silica nanoparticles in polypropylene glycol. The shear rheology of these suspensions was found to demonstrate dynamic shear-thickening behavior owing to the formation of large hydrodynamic clusters. The critical value of angular frequency for the onset of shear-thickening was found to increase monotonically with decreased strain amplitude. The extensional rheology of all the tested suspensions demonstrated modest strain-hardening at low strain rates. At a critical extension rate, a dramatic increase in both the speed and magnitude of the strain-hardening is observed for both the 25 wt% and 30 wt% suspensions with increasing extensional rate. The steady state extensional viscosity as a function of extension rate shows sharp extensional thickening transition very similar to shear flows. The increase in strain-hardening is likely due to the formation of strings and clusters ordered in the flow direction. This hypothesis is confirmed by small-angle light scattering measurements of the flow of the nanoparticle suspension through a microfluidic hyperbolic contraction. The degree of alignment of nanoparticles is quantified from the analysis of the scattering patterns and found to increase significantly with increasing extension rate.
| Item Type: | Article |
|---|---|
| Additional Information: | Rothstein, JP (reprint author), Univ Massachusetts, Dept Mech & Ind Engn, Amherst, MA 01003 |
| Uncontrolled Keywords: | WORMLIKE MICELLE SOLUTIONS; CONCENTRATED SUSPENSIONS; COLLOIDAL DISPERSIONS; POLYMER-SOLUTIONS; BROWNIAN SUSPENSIONS; SILICA SUSPENSIONS; PARTICLE-SIZE; VISCOSITY; FLOW; FLUIDS |
| InterNano Taxonomy: | Nanomanufacturing Processes > Bulk Structured Material Synthesis Methods > Liquid suspension Nanomanufacturing Characterization Techniques > Mechanical Property Characterization Nanoscale Objects and Nanostructured Materials > Nanoparticles |
| Collections: | Nanomanufacturing Research Collection > Nanomanufacturing Nanoscale Science and Engineering Centers > Center for Hierarchical Manufacturing Nanomanufacturing Research Collection |
| Depositing User: | Moureen Kemei |
| Date Deposited: | 27 Jan 2010 22:50 |
| Last Modified: | 19 Sep 2011 20:42 |
| URI: | http://eprints.internano.org/id/eprint/243 |
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