Preparation of Well Dispersed systems: The Role of Oxide Bridging in Agglomerate Formation

Publication Reference: 
Author Last Name: 
D M Smith
Report Type: 
ARR - Annual Report
Research Area: 
Particle Formation
Publication Year: 
Publication Month: 
United States


The effect of solvent surface tension, pH of water and surface chemistry of particles on agglomerate strength was studied using silica and titania agglomerates washed with different solvents. Aprotic solvents of various surface tension and water at various pH (with and without electrolyte) were employed to separate the effects of capillary pressure and particle-particle condensation reactions. The wetting hehavior of the solvent was studied using both the imbibition method and the modified wilhelmy plate technique. The two techniques were compared to determine their limitations when applied to spherical particles. Agglomerate strength was determined using a calibrated ultrasonic field, mechanical shear and isostatic compaction. Organic groups present on the particle surface were identified using infra-red adsorption and 13C NMR and the effect of the groups on agglomerate strength was discussed. The strength and strength distribution of the agglomerates formed was found to depend on the solvent surface tension, wetting characteristic, pH and surface chemistry of the particle. The presence of electrolyte in the solvent was found to effect the extent and strength of agglomeration, specially at higher pH. Agglomerate strength was also found to increase with increasing capillary stresses, and pH of water.