BASIS FOR DETERMINATION OF BRANCHING IN POLYMERS BY USE OF GEL-PERMEATION CHROMATOGRAPHY

The technique for determining branching in polymers by using a combination of GPC and intrinsic viscosity data has been extended beyond current methods. Equations used in these analyses are presented. The derivations are based upon the assumption that branching is present only when there is a measurable reduction in the intrinsic viscosity. Techniques for calculating the functionality of the star branch point in star-branched polymers are given. Three random-branching parameters are calculated from a knowledge of the average branching density: the lowest mol. wt branched polymer that can be measured; the average mol. wt between branch points; and the weight percentage of polymer that is branched. The applicability of this technique is demonstrated by using an analysis of published data on characterized fractions of a randomly branched PS.