The high trans-configuration butadiene-isoprene copolymers have been synthesized in the presence of TiCl4/MgCl2-Al(i-Bu)3 catalysts when butadiene mole content in the feed are between 0.55～0.148. The sequence structures of trans-butadiene-sioprene copolymers have been determined by 13^C NMR spectrometry. The dyad sistributions, composition and number-average sequence length of these copolymers are calcuated on the basis of assignment of 13^C NMR spectra. The results indicate that the sequence distributions of monomer units in copolymer follw first-order Markov model according to calculations. The products are sequence-iregular copolymers.

Key words: TITANIUM, BUTADIENE, ISOPRENE, COPOLYMERS, CATALYTIC REACTION, C13 NMR SPECTROMETRY, SEQUENCE DISTRIBUTION