| abstract |
Pipe with an outer diameter of from 90 to 630 mm and a minimum wall thickness of higher than 3.6 mm, having (a) an extrapolated time-to-failure (ASTM F2023 and ASTM F2769-10, performed on 16 mm SDR 7.4 pipe) of at least 50 years (for classification code CL5), (b) a time to failure (ISO 1167, performed on 32 mm SDR 11 pipe) of at least 10000 hours (110° C. under hoop stress of 2.6 MPa), and (c) a resistance to slow crack growth (ISO 13479 (80° C., 9.2 bar, performed on 110 mm SDR 11 pipe)) of at least 5000 hrs. The pipe contains a copolymer of ethylene and an a-olefin, and has (a) a density (D) in the range 933-948 kg/m 3 , (b) a melt index (MI 2 ) in the range 0.15-2.0 g/10 min, and (c) a melt elastic modulus G′ (G″=500 Pa) in the range 40 to 150 Pa. |