Software sensor for the bulk polymerization of systems exhibiting the Trommsdorff effect using viscosity measurements

A model-predictive software sensor was developed for on-line estimation of monomer conversion and average molecular weight during bulk polymerization of systems exhibiting a gel effect. The viscosity and temperature of the re action mass are the measured secondary variables, which when used with the model allow the state of the system to be estimated. The viscometer-reactor assembly was modified so as to measure the viscosity of the reaction mass during bulk polymerization of methyl methacrylate (MMA) at temperatures hig her than those reported in our earlier work (Mankar, R. B.; Saraf, D. N.; G upta, S. K. Ind Eng Chem Res 1998, 37, 2436). The viscosity data were curve -fitted using the modified Martin equation. Optimal temperature histories w ere then computed off-line, using a genetic algorithm, and implemented on t he viscometer-reactor assembly in which the bulk MMA polymerization was car ried out. The fact that the model tuned with the data obtained under the is othermal reactor operation can be used to predict the viscosity for nonisot hermal (optimal or otherwise) reactor conditions without further tuning est ablishes the efficacy of the software sensor. This study can now be extende d to investigate, experimentally, the on-line optimizing control of bulk MM A polymerizations. (C) 1999 John Wiley & Sons, Inc.