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Creaming of Emulsions with Adsorbing Polymer

So- far only non-adsorbing polymers have been considered, which flocculate by a depletion mechanism. Other molecules, which are slightly hydrophobic, may be able to be adsorbed at the oil-water interface. To prepare an emulsion a surfactant is also needed, but the surfactant is slowly displaced at the interface by the polysaccharide molecules. Adsorbing polymers are well known in colloid science, and their effect on the dispersion stability depends on the surface coverage of the polymer. At high concentrations, the drop surfaces are completely covered and [Pg.133]

04 days 1.29 days 3.31 days 5.18 days 6.24 days 7.33 days 8.27 days 15.1 days 92.3 days [Pg.136]

At higher polymer concentrations a network was formed, but usually it creamed a small amount first. It is not yet established whether there is a delay period in the case of bridging flocculation. The explanation offered above for the delay in depletion flocculation may also be relevant to bridging, but in the latter case it is likely that the droplets are less able to rearrange by rotating around each other. [Pg.137]

Flocculation by a bridging mechanism is well known for particle suspensions, where it is straightforward to adsorb polymers onto surfactant-free interfaces, but it is less commonly observed in emulsions. An exception is a protein-stabilised emulsion where the protein acts as a surfactant, but can cause bridging when there is incomplete surface coverage. [Pg.137]


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