On-Line Particle Diameter for Poly(Vinyl Acetate) Latex Using Specific Turbidity Method

This paper outlines the design and testing of an analyzer system for continuous poly(vinyl acetate) latex production that measures solids fraction and mean particle diameter from on-line measurements of latex density and dilute latex turbidity. The solids fraction is calculated from density, all flow rates into the reactor, and knowledge or estimates of all constituent densities. Mean diameter is calculated from the solids fraction and the UV turbidity of a diluted sample. The latex from the reactor effluent is sampled and diluted using a simple and robust system whose design is detailed in this paper. Error propagation analysis shows that, with 2% error in reactor inlet flow rates, the standard deviation of the solids fraction is 1%, that of the monomer conversion is 10%, and that of the mean particle diameter is 3%. On-line experimental results on a pilot-scale continuous vinyl acetate latex reactor show that the analyzer system easily resolves changes in solids fraction of less than 5% of value (0.5% solids al 10% solids) and changes in mean particle diameter of 10 nm.