MASS-SPECTRAL DETERMINATION OF CYCLIC OLIGOMER DISTRIBUTIONS IN POLYMERIZATION AND DEGRADATION REACTIONS

Mass spectral data have been directly used for the first time to determine the distributions of cyclic oligomers formed during polymerization and degradation reactions. In the text are presented several cases illustrating polymerization and thermal degradation reactions occurring in polyesters, polyamides, and polysulfides. The experimental distributions of cyclic oligomers allow discrimination between thermodynamically and kinetically controlled cyclization processes. In the former case the cyclic oligomer concentration decreases with n-2.5, and in the latter with n-1.5. The exponent in the cycle distribution law indicates therefore if the cyclization process is occurring through a back-biting or an end-biting reaction.