An adaptive calorimetric measurement strategy for on-line monitoring of conversion in polymerization processes

Much research effort has been devoted to the development of sensors capable of providing reliable on-line information about the reaction advancement in polymerization processes. In particular, calorimetric techniques which have been widely investigated in the past, still present real difficulties in multipurpose industrial applications. This paper describes a new strategy for the accurate determination of conversion during batch polymerizations. In addition to the calorimetric data, infrequently-available gravimetric measurements are used to track variations of key-parameters such as the overall heat transfer coefficient. It is shown that accurate estimation of conversion can be obtained, even if unpredictable conversion-dependent and/or batch-to-batch variations are encountered. Batch and semi-batch experiments were performed in a 7-1itre bench-scale well-mixed reactor to evaluate the technique. The method has been successfully applied to solution polymerization systems, i.e. vinyl acetate/butyl acrylate in ethyl acetate, and to emulsion copolymerization operations, i.e. styrene/butyl acrylate or methyl methacrylate/vinyl acetate.