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The rheology of carbon black dispersions

Barrie, Claire L. 2004. The rheology of carbon black dispersions. PhD Thesis, Cardiff University.

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Abstract

The interaction of carbon black with an acrylic resin in aqueous solution has been investigated by rheology. Two carbon blacks Raven L and Raven M, with similar particle size and surface characteristics but quite different particle morphologies, have been examined. In the absence of polymer, stable aqueous dispersions could not be obtained. Stable dispersions could be obtained however upon addition of polymer to a level corresponding to a ratio of 50mg of polymer per 13m2 of surface area (i.e.l5wt% particles). These stable dispersions exhibit flow typical of concentrated dispersions - Newtonian behaviour up to some apparent 'yield' or critical value. Above which shear thinning is observed. This critical stress increases with increasing polymer concentration. At low polymer concentrations, the dispersions are predominantly viscous at low shear stresses. The phase angle decreases significantly over a narrow shear stress range and the rheology tends to more elastic behaviour. At higher shear stresses, the dependence on particle morphology is weak. Furthermore, increasing the pH of the aqueous dispersions has little effect, but changing the adsorbent does alter the rheology somewhat. In addition to Raven L and Raven M, other carbon blacks were also investigated in which the surface chemistry had been modified by ozonolysis. In addition to aqueous systems, a selection of oil based systems have also been investigated. Here, four carbon blacks were used with a bitumen binder: the low-medium structured fine particle (Raven L), the medium-high structured fine particle (Raven M), a low-medium structured coarse particle (N772) and a medium-high structured coarse particle (N660). For these systems, the rheology and the dispersion colour properties have been investigated. Finally, a rheology study on the effect of bimodal dispersions was undertaken.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
ISBN: 9781303163289
Date of First Compliant Deposit: 30 March 2016
Last Modified: 09 Jan 2018 20:40
URI: http://orca-mwe.cf.ac.uk/id/eprint/55538

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