A SIMULATION-MODEL FOR LONG-CHAIN BRANCHING IN VINYL-ACETATE POLYMERIZATION .2. CONTINUOUS POLYMERIZATION IN A STIRRED-TANK REACTOR

A new simulation model for the kinetics of long-chain branching formed via chain transfer to polymer and terminal double-bond polymerization that was proposed in Part 1 of this series is extended to a continuou s stirred tank reactor. The present model is applied to the free radic al polymerization of vinyl acetate in a micromixed continuous stirred tank reactor, and various information on branched structure such as th e molecular weight distribution, distribution of branch points, and br anching density of the largest polymer molecule are calculated. Based on the present simulation model, it was found that the method of momen ts used successfully to predict various average properties in a batch polymerization cannot be applied to a continuous stirred tank reactor without accounting for the outflow of polymer radicals and the existen ce of polyradicals. The present model has given an excellent agreement with the experimental results of Chatterjee, Park, and Graessley (197 7) for a solution polymerization of vinyl acetate in a continuous stir red tank reactor. (C) 1994 John Wiley & Sons Inc.