C-13 NMR ANALYSIS OF COMPOSITIONAL HETEROGENEITY IN ETHYLENE PROPYLENE COPOLYMERS

C-13 NMR and temperature rising elution fractionation (TREF) are combined to characterize compositional heterogeneity in an ethylene-propylene copolymer. A methodology is developed involving systematic treatment of data via a computer-assisted analytical approach. The result indicates that the ethylene-propylene copolymer made with a heterogeneous titanium-based catalyst contains three or four separate components, each of which approximately obeys Bernoullian statistics. The Bernoullian probabilities vary from 0.03 to 0.60 and reflect the large differences in ethylene/propylene selectivity of different catalytic sites.