Procedure for calibrating an ultrasonic sensor for online monitoring of conversion in latex reactors

In order to estimate online conversion and polymer composition through soun d velocity measurements, a mathematical model for calculating sound velocit y in emulsion polymerization has been developed. With respect to previous m odeling approaches, its main features are as follows: (1) the application t o three-phase, reacting systems of Urick equation (usually adopted for esti mating sound velocity in multiphase, dispersed, unreacting systems, such as emulsions and suspensions); and (2) the development of an empirical relati onship for estimating particle compressibility as a function of conversion during the reaction. The model has been validated through several sets of e xperimental data of batch and semibatch homo- and copolymerizations involvi ng styrene, butyl acrylate, vinyl acetate, and methyl methacrylate. In most of the examined cases, the performances of the calibration model are satis factory. (C) 1999 John Wiley & Sons, Inc.