Nejabat, Gholam-Reza, Nekoomanesh, Mehdi, Arabi, Hassan, Salehi-Mobarakeh, Hamid, Zohuri, Gholam-Hossein, Omidvar, Mojtaba, and Miller, Stephen A.
The effect of adding various aluminum alkyls (R = Et, i-Bu) on the polymerization of propylene is studied using a (2-PhInd)2ZrCl2 pre-catalyst. A mild deactivating effect is found upon addition of TIBA, whereas TEA shows a sharp deactivating effect. Increasing amounts of AlR3 results in a significant activity increase for TIBA, but an activity plateau for TEA. AlR3 imposes remarkably different effects on the molecular weight and stereochemical microstructure of polymers. As the TIBA concentration increases, $\overline {M} _{{\rm v}} $ increases at first, growing from 49 000 to 72 000, but subsequently drops to 40 000. For TEA, $\overline {M} _{{\rm v}} $ decreases sharply, plummeting from 49 000 to 17 000. Both TIBA and TEA increase the mmmm pentad content from 7.9 to 23.5% and 17.6%, respectively. [ABSTRACT FROM AUTHOR]