THE ON-LINE MONITORING OF METHYL METHACRYLATE - VINYL ACETATE EMULSION COPOLYMERISATION
Résumé
An adaptive calorimetric method, coupled with state estimators for emulsion copolymerisation is shown to provide accurate, on-line information on the evolution of the composition and kinetics of an emulsion copolymerisation reactor. This method was evaluated for the emulsion copolymerisation of MMA-VAc under non-isothermal conditions. In addition to providing on-line estimates of the number of moles of each polymerising species in the reactor, the state estimator provides a value for a lumped kinetic parameter proportional to the product of Np. This information can be combined with off-line measurements to study the evolution of polymerisation kinetics, and to explain the trends observed for the molecular weight distribution and glass transition temperatures. Values of were found to vary from 0.5 to 30 for the homopolymerisation of MMA. However, the presence of VAc in the copolymerising system drastically reduces . This can lead to an dramatic increase in the average molecular weight of the copolymer since it alters the ratio of propagation to termination in the polymerising particles.