Studies in chain transfer. III. Determination of chain transfer coefficients from catalyzed polymerization data

Based on a general equation correlating DP and rate for catalyzed polymerization in the presence of solvents, an experimental method has been devised for determining all three transfer coefficients, viz. monomer transfer (CM), solvent transfer (CS), and catalyst transfer (CI), in a simple and straightforward way. Three types of methods are possible for solvent transfer determination: (1) by determining the slope of at constant 1 (catalyst): M (monomer) ratio; (2) by determining the intercept of at constant S/M; and (3) by direct use of the general equation, especially using a catalyst whose CI is known to be zero. It has been further shown that the existing method (slope of 1/P versus S/M) in uncatalyzed polymerization would give correct results for all solvents only over the range in which the rate of uncatalyzed polymerization is proportional to the square of monomer concentration. It has also been pointed out that, in systems in which the more usual rate equation, RP = KP (ki/kt)1/2I1/2M3/2 is valid, the slope of 1/P versus S/M (at constant I/M) would give correct CS values for catalyzed polymerization also.