Application of an Adaptive Controller to Molecular Weight Distribution Control in a Batch Polymerization Process

Abstract

This paper proposes a new control strategy of the reactor temperature and initiator concentration in order to get a final product of polymer which has a prescribed molecular weight distribution (MWD) in a free-radical polymerization batch reactor. First, profiles of instantaneous average chain length and polydispersity are obtained so as to get the desired MWD. Next, time profiles of reactor temperature and initiator concentration are determined from the profiles of instantaneous average chain length and polydispersity based on the mathematical model of the reactor. This two-steps method described above does not include any iterative calculation. Thus, the solution can be obtained more easily by this method than direct searching methods in which iterative calculations is required for obtaining time profiles of temperature. As the final step, the required time profile of the reactor temperature should be practically realized. Since the batch polymerization process is highly nonlinear and time-dependent, the time profile of reactor temperature was realized by the Adaptive Internal Model Controller (AIMC) developed by the authors.