Abstract: Polyethylene-based composition for which the standard density, measured at 23° C. according to ASTM Standard D 792, is greater than 940 kg/m3 and which comprises talc in an amount of less than 1 part per 100 parts by weight of polyethylene. The composition is preferably in the form of extruded granules. It exhibits a markedly improved creep resistance. Process for the manufacture of shaped articles and articles shaped from the composition, in particular pipe couplings and pipes intended for the transportation of pressurized fluids.

Abstract: Polyethylene-based composition for which the standard density, measured at 23° C. according to ASTM Standard D 792, is greater than 940 kg/m3 and which comprises talc in an amount of less than 1 part per 100 parts by weight of polyethylene. The composition is preferably in the form of extruded granules. It exhibits a markedly improved creep resistance.

Abstract: An ethylene-polymer-based composition obtained by mixing, in the melt: 100 parts by weight of an ethylene polymer withfrom 0.0005 to 0.1 part by weight of a compound (a) with the ability to generate free radicals andfrom 0.0005 to 0.1 part by weight of coagent (b) chosen from among the C.sub.3 to C.sub.12 alkenes and the C.sub.5 to C.sub.16 alkadienes.This composition has clearly improved melt strength. It is very suitable for extrusion and rotational molding and in particular for the extrusion of tubes intended for conveying fluids under pressure. The invention also relates to a process for obtaining the composition and using it for the manufacture of shaped articles, and to shaped articles.