THE EFFECT OF POLYMER BRIDGING ON THE FLOCCULATION KINETICS OF COLLOIDAL DISPERSIONS

Relative coagulation and flocculation rates of negatively charged colloidal dispersions (silver iodide sol, arsenic trisulphide sol, polystyrene latex) in the presence of electrolyte and small amounts of methylcellulose (MC), polyvinyl pyrrolidone (PVP) or 1:1 (w/w) MC-PVP mixture, have been determined by measuring the change in optical density of the dispersion with time. It was found that the adsorbed polymer may enhance or diminish the rate of successful encounters between particles, even at low surface coverages, depending on the magnitude of the interparticle electrostatic repulsion.