Predicting Average Molecular Weights and Branching Level for Self-Condensing Vinyl Copolymerization in a CSTR

摘要

A continuous stirred- tank reactor ( CSTR) model is developed to produce arborescent polyisobutylene via carbocationic copolymerization of isobutylene and inimer using multidimensional method of moments. The model is used to predict dynamic changes in average branching level ( Bkin) and numberaverage and weight- average molecular weights ( Mn andMw). Simulations of this self- condensing vinyl copolymerization ( SCVCP) show a tendency toward higher polydispersity and higher Bkin compared to batch reactor simulations conducted using the same recipes and residence times. At high inimer feed concentration and/ or long residence time, the model predicts that a CSTR does not reach steady- state operation due to Mw increasing toward infinity. There is a narrow operating range in which inimer feed concentrations can be adjusted to achieve a desired steady- state Mw. If SCVCP is to be conducted in a CSTR, it will be important to ensure that residence times and inimer feed concentrations are selected within the stable operating window.