Copolymerization and characterization of ethene–1‐hexene copolymers prepared by using the (Me5Cp)2ZrCl2–MAO catalyst system

It is demonstrated that the catalyst system bis(pentamethylcyclopentadienyl)‐zirconium dichloride (Me₅Cp)₂ZrCl₂–methylaluminoxane (MAO) is able to produce random copolymers of ethene and 1‐hexene. The 1‐hexene incorporation in the copolymers is extremely small. Even in the case of a molar ratio of [ethene] to [1‐hexene] of 1/20 in the monomer feed, only 1.4 mol % 1‐hexene are incorporated according to ¹³C nuclear magnetic resonance (NMR) spectra. Nevertheless, the physical properties of the random copolymers change significantly in this small range of 1‐hexene incorporation, from a high‐density polyethene to a linear low‐density polyethene. Thus, the melting temperature, the degree of crystallinity, the density and lamella thickness, and the long period of the alternating crystalline and amorphous regions decrease with increasing 1‐hexene content in the random copolymers. Blends of high‐density polyethene prepared with the system (Me₅Cp)₂ZrCl₂–MAO and an elastomeric random copolymer of ethene and 1‐hexene are phase‐separated and show good compatibility, as demonstrated by transmission electron microscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 439–447, 1999