Influence of catalyst depletion or deactivation on polymerization kinetics. II. Nonsteady‐state polymerization

The number-average and weight-average degrees of polymerization at the end of the polymerization process have been calculated in terms of the initial monomer concentration, initial catalyst concentration, and rate constants for various polymerization processes, all of which assume instantaneous initiation. The mechanisms differ among themselves in that there is either first-order catalyst deactivation, or transfer to monomer, or both. The calculation is greatly simplified if only the molecular weights at the end of polymerization are considered. The method given is particularly useful for systems where the calculation of the distribution function as a function of time is complicated. The fact that the monomer concentration and catalyst concentration have a marked effect on the molecular weight provides a good test of the validity of the mechanism under consideration. A comparison of the calculated and observed molecular weights obtained for the homogeneous polymerization of acrylonitrile with an organometallic catalyst will be given in a later communication.