AN ANALYTIC APPROACH IN KINETIC MODELING OF ZIEGLER-NATTA POLYMERIZATION OF BUTADIENE

Abstract

A kinetic modeling study was conducted for the Ziegler-Natta polymerization of butadiene with cobalt octoate/DEAC/water catalyst. The model equations for the single and dual active site models were analytically solved, and the closed-form expressions for conversion and both number and weight average molecular weights were obtained. The expressions for conversion and number average molecular weight are identical for both models. Also, the expressions of weight average molecular weight are similar for both models, but the expression for the dual active site model includes an additional scalar parameter. The parameter can be regarded as a ''correction factor of weight average molecular weight,'' which reflects the effect of dual active sites on the polydispersity. Using the expressions, a simple and noniterative kinetic modeling algorithm was established, and the parameter estimates were obtained. The estimated value of the correction factor ranges from 1.2 to 1.5 depending on the experimental data. The modeling results indicate the validity of the dual active site model. (C) 1994 John Wiley and Sons, Inc.