Cluster fragmentation in electrolyte induced aggregation of latex

Abstract

The scaling description of the aggregate size distribution cg (t), the number average N(t), and weight average S(t) cluster sizes are given for typical time-dependent coagulation–fragmentation processes. In initially concentrated suspensions, two modes of cluster growth are displayed. In a first mode, the process develops with a reduced size distribution that can be described in terms of irreversible diffusion-limited aggregation. In a second mode, the cluster growth develops in accordance with a reduced size distribution of a typical reaction-limited aggregation process (RLA). In diluted suspensions, the clusters only grow with the reduced size distribution of the RLA type. In all situations, two regimes are determined. In the first regime, N(t) and S(t) scale with tz , where the exponent z is dependent on the colloid concentration. The second regime is characterized by the presence of a constant number of clusters with a monotonically increasing mean cluster mass. These observations result from the fact that the breakup of aggregates mainly generates fragments of very low size.