PRESSURE PIPES AND POLYOLEFIN COMPOSITION FOR THE MANUFACTURE THEREOF

摘要

Articles, particularly pressure pipes, having high strength as well as high stiffness and very good impact resistance even at low temperatures can be obtained by using a heterophasic polyolef?n composition comprising (percent by weight) 70-90% of a random copolymer of propylene with 0.5-6% of 1-hexene, and 10-30% of a polymer of ethylene with a C3-C10 a- olef?n and optionally a diene, wherein the polymer of ethylene has an ethylene content higher than 45% and an intrinsic viscosity [?] value from 3 to 5 dl/g. A particular advantage of the present invention is that articles comprising the above heterophasic polyolef?n composition show a low ductile to brittle transition temperature (DBTT).