AGGREGATION FRAGMENTATION PROCESSES IN UNSTABLE LATEX SUSPENSIONS

Standard scaling laws were found to apply in reversible aggregation processes. The influence of fragmentation on cluster size distribution and mean cluster size was determined and it was shown that concomitant aggregation and fragmentation processes lead to establishment of a dynamic equilibrium characterized by the existence of constant mean cluster sizes. Small variations of the surface charge characteristics led to different structures of the colloid suspension. In the steady state regime the colloid suspension was characterized by a size distribution function of the form cg ∼ g-τ, cg being the concentration of aggregates of g elementary grains, and the exponent τ being pH dependent. The τ values were smaller than unity thus differing from 1.5, which would correspond to a reaction limited aggregation process. By applying the correlation between cluster size frequency and mode of fragmentation resulting from a computer simulation study to these results, possible mechanisms for the electrolyte induced aggregation/fragmentation processes were deduced. © 1990.