Ethene/Propene Copolymerizations from Metallocene-Based Catalytic Systems: The Role of Comonomer Concentrations

Ethene/propene copolymerizations were performed with rac-[ethylenebis(4,5,6,7-tetrahydro-1-indenyl)]zirconium dichloride (r-EBTHIZrCl2) and tetraisooctylaluminoxane (TIOAO). Copolymerizations were carried out at three levels of comonomer concentrations, in a range from about 0.011 M to about 2.6 M. The reactivity ratios of copolymerizations (r11, r21, r22 and r12) and the relative reactivity of the comonomers (R) were determined, for all the adopted experimental conditions. Tests and reported data indicate that they are substantially the same over a broad range of comonomer concentrations, thus making metallocene based catalytic systems potentially suitable for industrial application. The effect of the polymerization solvent, either aliphatic or aromatic, is also briefly discussed.