Linear low density polyethylene from ethylene as an only monomer was prepared by the combination catalyst system of Et (Ind)2ZrCl2 and {2-[2-Me-4-Br-C6H3N=C(Me)]2C5H3N}FeCl2 activated with methylaluminoxane (MAO) The two catalysts were well matched in a single reactor and it was observed that the “comonomer effect”appeared in the in-situ eopolymefization of ethylene The comonomer effect was some strongly influenced by the molar ratio of Al to (Fe+Zr) and the polymerization temperatures At 60℃ and n(Al)/n(Fe+Zr)=2000

the maximum activity of the catalytic system(8.5×106g/mol·h) was 4.25 times higher than that of homopelymerizationof ethylene(2.0×106g/mol·h)

andthe value of n(Fe)/n(Zr) was 0.5．At n(Al)/n(Fe+Zr)=1000

the maximum activity diminished．When polymerization temperatures increased

the maximum activity of the in-situ copolymerization decreased and the corresponding ratio of Fe to Zr also decayed．The eopolymers made from this catalytic system had the characteristics of low melting point (from 132.34℃ to 70.97℃)

low density (from 0.9467g/cm3 to 0.9283 g/cm3) and narrow molecular weight distribution(from 2.29 to 1.86)．However

it’s no obvious influence of the comonomer effect on the physical properties of the copolymers．