Effect of adsorption behaviour of polyelectrolytes on fluidity and packing ability of aqueous graphite slurries

- The cyclic structure of CMC allows it to easily adsorb onto graphite powder.
- Addition of CMC is effective in dispersing relatively hydrophobic graphite powder.
- Addition of Na-PAA is effective in dispersing relatively hydrophilic alumina powder.

The effect of surface hydrophobicity on the adsorption behaviour of polyelectrolytes is investigated using graphite and alumina powder slurries. Graphite slurries containing carboxymethylcellulose (CMC) have a relatively low apparent viscosity and afford a sediment with a relatively high packing fraction as compared to that obtained when using sodium polyacrylate (Na-PAA) as a dispersant, although both have the same functional group. As a greater amount of CMC is adsorbed, it is concluded that its adsorption mechanism involves hydrophobic interaction, thus making it a better dispersant for hydrophobic powders in aqueous media. In contrast, Na-PAA is more effective in dispersing relatively hydrophilic powders such as alumina, as it adsorbs mainly through electrostatic interactions.

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