Flocculation of PVC Latex Particles in the Presence of Vinyl Chloride
addition of a flocculating polymer to the latex,
addition of VCM under thorough stirring, and
evaporation of VCM.
The PVC latex used was stabilized by ammonium laurate; the flocculating polymer was a polyvinyl alcohol with a low degree of hydrolysis. The agglomeration process was found to proceed in two steps. In the first, the particles flocculated and formed primary aggregates containing hundreds of latex particles. By addition of VCM these aggregates rapidly passed into the VCM phase forming macroscopic agglomerates, the precursors to the resin powder particles. During the passage into the VCM phase most of the laurate desorbed. The flocculating polymer also desorbed, but at a much lower rate.
During the evaporation step this polymer was readsorbed, whereas the laurate remained in the serum phase; during the last stage of this step, the specific surface area of the resin phase decreased sharply, indicating a large degree of particle coalesence.
KeywordsLatex Particle Sodium Lauryl Sulphate Vinyl Alcohol Recede Contact Angle Serum Phase
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