Correlation between Polymer Particle Size and in‐situ NIR Spectra

This work describes the estimation of polymer particle size from NIR spectra collected in situ and online in an automated reactor. A good linearity between spectra and average polymer particle diameter is found. The multivariate linear model is also tested with an independent data set not used in the model fitting. Despite varying monomer and polymer concentrations and temperature changes along the process, the average particle sizes are well predicted and can be monitored by NIR spectroscopy during emulsion polymerization reactions.

Evolution of average particle diameter with polymer content for three different BA/Sty semi‐continuous emulsion polymerization reactions. Open symbols correspond to spectra used in the model fitting and solid symbols to the test data set. The different symbol types correspond to the three different reactions.