No abstract

Polymerisation reactor design and mode of operation are particularly important for polymerisation processes where the lifetime of the growing species is long compared to the mean residence time of reactants in the reactor. For these reasons, reactor control strategies can be devised for living polymerisation processes in order to tailor the nature of the polymer produced, for example, molecular weight distribution. The strategies can only be devised for ideal reaction and reactor behaviour. Since neither are ideal, it is necessary to understand those factors which cause deviation from ideality. In this work, the influence of the spatial distribution of temperature and flow velocity is examined for an ideal classical living polymerisation reaction carried out in a tubular reactor under steady‐state reactor conditions using a computational fluid dynamics (CFD) code (PHOENICS) to explore the influence of the spatial distribution of species and temperature on the product with all other reactor features being ideal. Particular attention is given to the problem of describing the spatial distribution of the dispersity index (moments of the molecular weight distribution) of the polymer in addition to flow velocity, temperature, component concentrations and kinematic viscosity. Comparisons are made between the CFD predictions, simulations based on the ideal behaviour of the process, and the experimental results from a laboratory‐scale reactor. It is shown that the CFD predictions give a more realistic description of the tubular reactor behaviour for the conditions employed. The limitations of the CFD approach and the additional problems still needing to be addressed, such as mixing quality, are discussed.

It has been previously shown that it is feasible to control the molecular weight distribution (MWD) of polymers produced from living polymerization processes in flow reactors through the control of reactant feeds. Here, attention is given to the problem of establishing an inverse process model as a step toward a fully automatic control strategy for the synthesis of polymers with predefined MWD. Particular attention is given to the prediction of instantaneous reactor feed conditions for a specified product MWD. The reactor is modeled as an ideal continuous stirred tank reactor with constant monomer concentration in the reactor. The way in which a real laboratory-scale polymerization system can be developed from this approach is outlined.