Abstract: A new characterization method for determining the sequence distribution of ethylene-propylene copolymers, obtained with a supported Ziegler-Natta catalyst made by chemical reaction method, was carried out by ¹³C NMR spectroscopy. By dividing the ¹³C NMR spectrum into eight individual regions, triad sequence distribution and composition of EP copolymer were calculated through using fiveintegrals of these regions to avoid the use of the other three condition sensitive regions. Comparison of experimental versus calculated triad distribution points out that the first order Markovian model was more fit to the copolymer sequence distribution and the catalytic active sites are more favorable to ethylene and propylene homopoly merization.

Key words: Ethylene-propylene copolymer, ¹³C NMR spectroscopy, Sequence distribution, Bernoullian model, Markovian model