The influence of ageing and polymerization conditions on the polymerization of butadiene using a neodymium catalyst system

The homopolymerization of butadiene in the presence of a rare earth‐containing catalyst system was examined at 60°C. The catalyst system consists of neodymium octanoate, diethylaluminium sesquichloride and triisobutyl aluminium in n‐heptane. This catalyst shows high activity also at low polymerization temperature and yields polymers with a cis‐1,4 content of nearly 99%. The catalyst ageing and the polymerization conditions were varied and the behaviour of molar mass distribution, conversion and microstructure of polymers is illustrated. Attention is focussed on molar mass distribution of cis‐1,4‐polybutadiene samples which can be unimodal or bimodal in dependence on the preparation conditions.