Synthesis of Stereoblock Elastomeric Poly(propylene)s Using a (2‐PhInd)2ZrCl2 Metallocene Catalyst in the Presence of Co‐Catalyst Mixtures: Study of Activity and Molecular Weight
1. Polymerization Engineering Department, Iran Polymer and Petrochemical Institute (IPPI), P.O. Box 14965/115, Tehran, Iran;2. The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida, Gainesville, FL 32611‐7200, USA;3. Chemistry Group, Department of Science, Ferdowsi University of Mashhad, P.O. Box 1436, Mashhad, Iran
Abstract:
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.
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. 