The role of the homogenous and heterogeneous components of ziegler catalysts in the development of polymerization activity

The eomposition and polymerization activity of a given catalyst system (TiCI4-Et2AlCl) were determined. The solid particles formed by the reaction of the catalyst components were separated at two given times, which were characteristic of the polymerization kinetics. The polymerization activities of the catalyst precipitates were determined in the presence of Et2AlCl and other cocatalysts. It was established that the measured polymerization activities of the catalyst precipitates are higher in the initial system than in the presence of other cocatalysts. The composition of the liquid phase of the catalyst was studied and it was found to contain certain dissolved Ti compounds, the titanium content of which could be determined after hydrolysis as trivalent Ti. The concentration of this titanium compound depends on the solvent used. The polymerization kinetic studies provided evidence that the maximum polymerization rate, i.e., the process of polymerization as a whole, depends on the kind of the solvent used and thus on the quantity of dissolved titanium compounds in the liquid phase.