Factors affecting the promoted aggregation and coalescence of synthetic rubber particles

Abstract

AbstractSmall particles (ca. 700 A.) in an SB‐R latex can be agglomerated (aggregation and coalescence) to the large size and heterogeneous distribution required for fluid high solids latex. This agglomeration is promoted by high molecular weight materials such as polyvinyl methyl ether (PVM). The mechanism of this agglomeration has been investigated. The effects of controlled variations in the amounts of PVM, electrolyte, soap and latex solids content were determined using statistically designed experiments. The agglomeration was found to differ from Smoluchowski kinetics in that it could best be described by the relationship: (1/n) = (1/n0) + at − bt2 where n = particle number, t = time and a and b are constants. The agglomeration rates were about 1011 to 1012 times slower than the theoretical Smoluchowski rapid coagulation rate. Increases in PVM, soap, and latex solids increased the agglomeration rate. The agglomerations were self‐limiting and reached equilibria the level of which increased with increases in PVM and decreased with increases in soap. Regression equations relating the effects of the controlled variables on the agglomeration rate and the equilibria states are derived and presented graphically. The particle size distribution of the final latex was significantly correlated, with that expected from theoretical collision theory.