NOVEL COPOLYMERS

摘要

Novel copolymers are described comprising ethylene and alpha-olefins having (a) a density (D) in the range 930-960/g/m3 (b) a melt index (MI2) in the range 0.1-3.5 g/10 min (c) a melt elastic modulus G′ (G″=500 Pa) in the range 40 to 150 Pa, and (d) a ratio of complex dynamic shear viscosities &eegr;*(0.1)/&eegr;*(100) in the range 1.5 to 5.5. The novel copolymers are particularly suitable for use as Polyethylenes of Raised Temperature Resistance (PE-RT) for use in hot water piping systems. The novel copolymers may be prepared by use of meltallocene catalyst systems. Pipes having a time to failure of ≧500 hrs measured according to ISO 1167 at 110° C. and 2.6 MPa prepared in a single reactor are also disclosed.