Abstract: Three ethylene-propylene copolymers were investigated by ¹³C-NMR in an ordinary solvent (CCl₄) and at room temperature (22℃). For the present measurements, the resolution was higher and peaks were assigned comonomcr compositions and sequence distributions of these copolymers were quantitatively determined. The results show that samples A, B have sequence structures of block propylene and block ethylene mostly while Sample C has a tendency toward alternating propylene-ethylene-propylene sequences.
Two statistical models were used to deduce the mechanism of polymerization process.

Key words: ¹³C NMR, Comonomer composition, Sequence distribution