Kinetics of bridging flocculation. Role of relaxations in the polymer layer

Abstract

From experimental data on the kinetics of flocculation of polystyrene latex by means of poly(ethylene oxide) it is deduced that the well known classical aggregation theory of von Smoluchowski does not apply to bridging flocculation. A new kinetic model is therefore developed. It has as a key element the flattening of the polymer molecules with time, by which they lose the ability to form bridges. We take this into account by introducing a characteristic time of reconformation. The only other parameter is a minimum coverage of ‘active’ polymer chains per particle, necessary for bridge formation. Using reasonable values for these two parameters, we find that the model describes the experimental data very well.