Emulsion Polymerization of Vinyl Acetate: Particle Size and Molecular Weight Distributions

Abstract

<p>Emulsion polymerization of vinyl acetate was studied in a batch reactor system. The particle size distribution of the polyvinyl acetate particles was determined by electron microscopy. 'In Situ Polymerization' technique was used to harden the polymer particles before microscopic examination. A light transmission spectrophotometer was calibrated for particle size measurement with the data obtained from election microscopy. A one-parameter exponential function was found to be a good approximation for the polyvinyl acetate particle size distribution. A convenient method which involves the measurement of turbidities at two wavelengths was proposed to determine the particle size distribution.</p> <p>The second part of this thesis deals with the kinetics of vinyl acetate emulsion polymerization. It was found that a rate model similar to Case 1 of Smith-Ewart's theory was able to predict the polymerization rate. A model previously developed in this laboratory was able to predict the molecular weight development in vinyl acetate emulsion polymerization. The logarithmic-normal distribution was a reasonably good approximation for the polyvinyl acetate molecular weight distribution.</p>