Optimization of a cocktail of initiators for suspension polymerization of vinyl chloride in batch reactors

The industrial manufacturing of poly(vinyl chloride) (PVC) by suspension po lymerization is carried out in batch reactors. The productivity increase of these processes is directly related to the reduction of the time required to complete each batch. The reactor cooling system is designed such that it is capable to compensate for the maximum rate of heat release by the exoth ermic polymerization, so that the reactor cooling capacity is underutilized . An attractive mode of operation is to run the industrial process isotherm ally and to use a mixture ("cocktail") of different initiators, which is ab le to spread the polymerization rate over the batch time. In this work, the optimal formulation of an initiator mixture is studied as a dynamic optimi zation problem, which makes use of a representative mathematical model for the batch suspension vinyl chloride polymerization process. Results show th at by choosing the optimal amounts of initiators in the cocktail, a signifi cant reduction of the total processing time for a given polymer specificati on can be obtained, as compared to the case in which only one initiator is optimally chosen. (C) 2001 Elsevier Science Ltd. All rights reserved.