Heterogeneous Ethylene and Alpha‐Olefin Copolymerization Using Zirconocene Aluminohydride Complexes

Abstract

Summary: In this work we studied the copolymerization of ethylene and different alpha-olefins (propylene, 1-butene, 1-hexene, and 1-octene) using aluminohydride zirconocene systems supported on modified silica. The copolymerization reactions were carried out in hexanes, at different Al/Zr ratios, using two different comonomer concentrations. The effect of comonomer type on catalyst activity and polymer molecular weight and chemical composition distributions (MWD and CCD) was compared. Average comonomer incorporation was determined by 13 C NMR and the CCD by crystallization elution fractionation (CEF). Most of the copolymerizations showed very high catalytic activity (up to 4000 Kg PE/mol Zr), and the molecular weight was higher for the copolymers containing 1-octene, demonstrating that aluminohydride zirconocene systems can copolymerize ethylene and alpha-olefins effectively.

Coordination copolymerization monitoring of ethylene and alfa-olefins by in-line Raman spectroscopy

“…It is worth mentioning that other polymerization conditions like ethylene pressure and solvent, were stablished according to copolymerizations carried out in previous reports. 20 As for the Ziegler-Natta catalyst, a commercial h generation system from Grace Co., based on Ti, was utilized at 6.9 Â 10 −4 mol L −1 , which was activated with triethylaluminium (TEA) at Al/Ti ratios of 10, according to the usually conditions utilized for these systems. 11 In order to establish the initial amount of comonomer added batchwise or gradually dosed during the copolymerization reactions, preliminary reactions of ethylene homopolymerizations were carried out with both systems (metallocene or Ziegler-Natta).…”

“…It is worth mentioning that other polymerization conditions like ethylene pressure and solvent, were stablished according to copolymerizations carried out in previous reports. 20 As for the Ziegler–Natta catalyst, a commercial fifth generation system from Grace Co., based on Ti, was utilized at 6.9 × 10 −4 mol L −1 , which was activated with triethylaluminium (TEA) at Al/Ti ratios of 10, according to the usually conditions utilized for these systems. 11 …”