Emulsion Copolymerization of Acrylonitrile and Butadiene in an Industrial Reactor. Mathematical Modelling, Estimation, and Control of Polymer Quality Variables on the Basis of Calorimetric Measurements

Abstract

An industrial emulsion copolymerization of acrylonitrile and butadiene carried out in a batch (or semibatch) reactor for the production of nitrile rubber (NBR) is investigated. The effect of variable amounts of deactivating impurities on the predictions of a global polymerization model is analyzed; and the advantages of using the model predictions in combination with on-line calorimetric measurements are shown. The adjusted polymerization model allows to adequately monitor main quality variables of the process, such as: monomer conversion, average copolymer composition, average molecular weights, and degree of branching. The semibatch addition of the comonomers and/or the chain transfer agent along the reaction was investigated with the aim of controlling the polymer quality characteristics and increasing the productivity. It is possible to obtain a uniform-composition copolymer with pre-specified profiles of the average molecular weights or the degrees of branching. Furthermore, the NBR productivity can be increased by about 5%, without deteriorating the final copolymer quality with respect to that produced in the more conventional batch operation.