Polymer Versus Polymerization Fouling: Basic Deposition Mechanisms During Emulsion Polymerization by the Example of a Vinyl Acetate and Versa 10 Copolymer

The deposition process during emulsion polymerization can be classified as both particulate and reaction fouling, but a deeper understanding of the deposition mechanism, especially in combination with the polymerization process, is lacking. Here, a more in-depth understanding of the deposition mechanism is sought by investigating the fouling formation of a Vinyl acetate and Versa 10 copolymer on a heated stainless steel surface during emulsion polymerization. Its deposition behavior is also compared with the behavior of an already reacted polymer. All possible influencing factors are investigated separately, and the fouling is quantified by the mass based fouling resistance and the fouling layer composition. The fouling rates of both experimental approaches (ongoing reaction versus already reacted polymer) are used to determine the fraction of reaction fouling along the reaction pathway. The solids content and the driving temperature difference are identified as the main factors influencing fouling formation. The deposited material is composed of latex particles and emulsifier with particle size and number depending on the respective equilibrium composition of the fluid phase. The reaction fouling rate is correlated with the proportion of free initiator radicals and the amount of dissolved monomer in the aqueous phase.