This work studied ternary catalyst systems composed of neodymium versatate, t-butyl chloride and diisobutyl-aluminium hydride used in the cis-1,4 polymerization of butadiene in hexane. The effect of natural aging of the catalyst (1 to 60 days at 8.5°C) on the conversion, catalyst activity and on the micro and macrostructure characteristics of polybutadiene was investigated. The effect of forced aging by heating (40°C), of the different phases of the catalyst preparation on the polymerization characteristics and the synthesized polymer was also studied. The polymers were characterized by size exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FT-IR) and viscosimetry in solution and melted-state. Accelerated aging of the different phases of the catalyst (F1, F2, F3 and F4) affected the conversion and the catalytic activity in distinct ways. The results of the conversion and catalytic activity showed that F1 was the most affected phase by accelerated aging at 40°C. In this step the neodymium versatate was added to the solution of diisobutyl-aluminium hydride (Catalyst 447). The microstructure did not change with the natural aging of the catalyst while the macrostructure showed dependence on this variable. When the catalyst aging time increased from 1 to 10 days a slight increase in the conversion and the catalytic activity was observed.
Ziegler-Natta catalyst; neodymium; aging; polybutadiene
