Cardanol: A new dispersant for alumina in toluene

Cardanol, which is a naturally occurring C-15,, unsaturated aliphatic chain -substituted phenol derived from cashew nut shell liquid, was used as a dis persant for alumina in toluene. Adsorption data, along with the results of sedimentation studies, green density, and slurry viscosity (as a function o f dispersant concentration), suggest that cardanol adsorption initially pro ceeded through surface coverage by a phenolic group that lies flat on the s urface and that the best powder dispersion occurred at surface saturation b y more closely packed end-on adsorbed cardanol molecules. The alkyl-chain u nsaturation significantly contributed to dispersion, such that the saturati on by hydrogenation led to an increase in the slurry viscosity by a factor of similar to 2,5, Concentrated slurries generally showed shear-thinning fl ow behavior, and the measured viscosity of a highly concentrated (53 vol%) slurry was <1 Pa.s at a shear rate of 93 s(-1).