POLYMERIZATION OF ETHYLENE AND ETHYLENE 1-HEXENE OVER ZIEGLER-NATTA/METALLOCENE HYBRID CATALYSTS SUPPORTED ON MGCL2 PREPARED BY A RECRYSTALLIZATION METHOD/

MgCl2 for use as a catalyst support was prepared by dissolution in met hanol and recrystallization in n-decane, followed by vacuum-drying at 2,000 rpm. The prepared support was modified by treatment with alkylal uminum compounds. The activity profile of ethylene over the supported catalysts persisted for periods up to 1 h during the polymerization. T he prepared Ziegler-Natta/metallocene hybrid catalysts exhibited the c haracteristics of both metallocene and Ziegler-Natta catalysts. The po lymer produced by the hybrid catalysts gave bimodal peaks in different ial scanning calorimetry analysis for ethylene and ethylene/1-hexene p olymerization, suggesting that the polymer was composed of two differe nt lamellar structures that were polymerized by each catalyst. (C) 199 8 John Wiley & Sons, Inc.