POLYMERIZATION TIME AND TOTAL CATALYST CO NCENTRATION CHANGE CIS-1,4-POLYBUTADIENE

The homopolymerization of butadiene in the presence of a rare earth-co ntaining catalyst system was examined at 60 degrees C. The catalyst sy stem consists of neodymium octanoate, diethylaluminium sesquichloride and triisobutyl aluminium in n-heptane. This catalyst shows a high act ivity at 120 min polymerization time and yields polymers with a cis-1, 4-content of > 96%. The catalyst concentration was varied and the beha viour of molar masses and molar mass distribution, conversion and micr ostructure of polymers is illustrated. Attention is focussed on molar mass distribution of cis-1,4-polybutadiene samples which can be unimod al or bimodal in dependence on the preparation conditions.