On-line particle size determination in a latex reactor using dynamic light scattering

The particle size distribution as a critical parameter in emulsion polymerization because it influences the properties (and therefore end use) of the latex. On-line dynamic light scattering (connected to a proper diluter-sampler system) is capable of producing stable, reliable estimates of the particle size distribution in a total elapsed time of 10 to 20 mins. This time includes sample acquisition and dilution, temperature equilibration, autocorrelation build up and analysis, printing of results and storage of raw data and system flushing. The results presented here were obtained using a total cycle time of 17 minutes, of which approximately 5 min were devoted to data collection and analysis. For this poly(vinyl acetate) latex the Gaussian analysis was sufficient to obtain an accurate reproducible characterization of the PSD during all stages of the emulsion polymerization reaction.