Aggregation behavior and reversibility of sulfonated phenol formaldehyde resin

Abstract

ABSTRACTAggregation behavior of sulfonated phenol formaldehyde (SPF) resin in the presence of different valence salts and solution pH values was studied by measuring the change of dispersion turbidity with time. Electrophoretic mobility and hydrodynamic diameter of SPF resin aggregates were also measured under different salt conditions. Disaggregation behavior of SPF resin aggregates was characterized by manually shaking or ultrasound treatment. The result shows that that the size of SPF molecule aggregates and turbidity of the SPF resin dispersion were increased with the increase of Na+ and Mg2+ concentrations, and accordingly, the dispersion stability of SPF resin was decreased. The effect of Mg2+ on SPF resin molecule aggregation was more sensitive than that of Na+ as Mg2+ has a stronger charge screening effect on the repulsive forces between SPF resin molecules. H+ protonates –O− and – groups on SPF resin molecules, leading to a decrease of surface charge on the molecule; therefore the molecule aggregation was promoted and SPF resin dispersion stability was decreased. The reversibility of SPF resin aggregates was observed. The SPF resin aggregates could be disaggregated under ultrasound treatment. In addition, the disaggregated aggregates could recover to their original size at quiescent conditions.