Evaluation of different branching functions used in the determination of random branching by GPC



Three branching functions are evaluated for use in the measurement of random branching by GPC. Initial evaluations of the functions g1/2, g3/2, and h3 were made by computer simulations of GPC experiments using published data of lightly and highly randomly branched polymers. Actual GPC experiments were then performed on characterized samples of lightly and highly branched styrene–divinylbenzene copolymers. The results indicate that h3 adequately predicts branching and molecular weight at all branching densities, whileg1/2 is accurate only for lightly branched polymers and g3/2 is accurate only for highly branched polymers. A means for predicting the M–[η] curve for branched polymers from the M–[η] calibration curve for linear polymer is proposed.