Possibility was studied of synthesizing polypropylene-ethylene propylene copoly-mer-polypropylene (PP-EPR-PP) triblock copolymer with RR-TiCl3-Et2AlCl in slurry polymerization in heptane. Molecular weight (Mn)of PP increased with polymerization time; [η] of product in polymerization according to PP-EPR-PP scheme also increased with addition of successive blocks. In spite of evidence of chain-transfer (negligible with Et2AlCl)

especially through the isolation of a nonerystalline low MW fraction

it is suggested that block structure is obtainable on assumption of the presence of two di-fferent active centers.