Free radical polymerizations associated with the Trommsdorff effect under semibatch reactor conditions: an improved model

Abstract

Several important polymerizations (e.g., polymethylmethacrylate (PMMA)) exhibit the cage, gel and glass effects during polymerization. These are associated with diffusional limitations assuming importance with increasing viscosities of the reaction mass. A new model has been developed to account for these effects. The free volume theory has been used to account for the changes in the diffusion coefficients with time. The model parameters are tuned using experimental data on the isothermal bulk and solution poymerization on MMA on batch (ampoule) reactors. Unlike earlier theories, this model does not incorporate the initial values of the number averages chain length or initiatior concentration, and so can be used easily to simulate semibatch reactor operation as well as reactions under nonisothermal conditions. The model gives improved agreement with recent experimental data taken on 1-titer, PC – controlled reactor, on MMA polymerization under nonisothermal conditions, as well as with intermediate addition of initiator.