SIMULATION STUDY OF THE NITROXIDE MEDIATED COPOLYMERIZATION OF STYRENE AND ALPHA-METHYL STYRENE UNDER DIFFERENT REACTOR CONFIGURATIONS

ASTEASUAIN, MARIANO; FORTUNATTI, CECILIA; SARMORIA, CLAUDIA; BRANDOLIN, ADRIANA

Cancún

Conferencia; Polymer Reaction Engineering VIII; 2012

Engineering Conferences International (ECI)

Controlled radical polymerization (CRP) offers enormous possibilities for creating materials with uniqueproperties. CRP allows obtaining copolymers with controlled molecular weight, polydispersity, composition and chain architecture. One of the most studied mechanisms of CRP is the nitroxide mediated polymerization (NMP), in which the reaction is controlled through reversible termination with a stable radical. The propagation speed is reduced by the balance between concentrations of active and inactive species, which allows all chains to be initiated and grow on the average at the same speed.We developed a mathematical model to describe the nitroxide mediated controlled radical copolymerization that takes place under batch, semi-batch or tubular reactor configurations. Tubular reactors both with and without side feeds were considered. The model may predict average copolymer properties such as average molecular weights and composition, as well as the full bivariate MWD and the sequence length distribution. Double index moments were used for modeling the average properties, and 2D probability generating functions for the bivariate MWD. As an example of the model capabilities, the TEMPO mediated copolymerization of styrene and alpha-methyl styrene was analyzed. Simulations were carried out in order to assess the influence of different design and operating variables on the product properties for the batch, semi-batch and tubular reactors. It was observed that the range of attainable global compositions was largest in the case of semi-batch reactors. Alternatively, tubular reactors with side feeds allow production of material with large variations in chain composition. In addition to these differences in copolymer structure, implementation of an alpha-methyl styrene side feeding strategy was proven useful to achieve an increase in conversion, and, therefore, in molecular weights. The results obtained in this work aid in the understanding of the process and in the determination of the appropriate operating conditions necessary to achieve specific final properties.