ADSORPTION OF POLYELECTROLYTES AND STABIL ITY OF LATEX SUSPENSIONS

The adsorption of polyethylenimine and carboxymethylcellulose sodium s alts from aqueous electrolyte solutions and its effect on the sediment ation rate, volume of sediment, electrokinetic potential and degree of aggregation of homo-disperse polystyrene and melamineformaldehyde cop olymer particles were investigated. The adsorption isotherms are of hi gh-affinity type and may be described by the Hesselink theory of polye lectrolyte adsorption. Starting from the calculated values of the adso rption layer thickness and the segment densities in polymer coils and adsorption layers a considerable deformation of polymers during adsorp tion was assumed. It was shown that the flocculation of suspensions by polyelectrolytes takes place far from the isoelectric point of partic les. The role of electrostatic, structural and steric forces in the me chanism of stabilization of dispersions by oppositely charged polyelec trolytes is discussed.