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Auteur : Latifa ALIMI
Année : 2007
Domaine : Génie mécanique
Type : Mémoire de magister
Etablissement : Université Badji Mokhtar de Annaba
Résumé en PDF : (résumé en pdf)
Fulltext en PDF : (.pdf)
Mots clés : polyethylene, Pipe, mechanical properties, pipe wall, aggressive environment, degradation

Résumé :

Nowadays, the high density polyethylene resins (HDPE) are generally transformed into pipes and assemblies on a large scale to build the natural gas distribution and transmission systemsThe polymeric materials are largely used by various industrial applications like the transport of liquids under pressure.Several researches are centred on the development of new resistant and durable resins in the aggressive environments. It is the case of the high-density polyethylene. This study relates to the preparation and the test ofthe standards specimens machined under specific conditions. The adopted norm is ISO 527. The effect of the corrosive conditions like solvents containing benzene and the bases is discussed according to the exposure times.The results are expressed in the form of mechanical properties standards (E, σy, σCD, σu, Ɛy ). It arises that deterioration is significant and varies proportionally at the exposure time. Attenuation of E and E, σy, can arrive up to 25% of the starting value. On the level mechanisms, it is advanced the degradation of the molecular chains (segmentation) and also the hardening under the effect of external forces.