(1) Département de Génie des Procédés, Université Akli Mohand Oulhadj - Bouira - Algérie, (2) Département de Génie de l'environnement, Ecole Nationale Polytechnique - El-Harrach, Alger - Algérie, (3) Département de Génie des Procédés, Faculté de Technologie, Université Ferhat Abbas - Sétif - Algérie, (4) INSA-Lyon CNRS UMR 5223, Ingénierie des Matériaux Polymères - Villeurbanne - France
The main purpose of this work is to evaluate the long term performance of butt welded polyethylene pipes in comparison to not welded counterparts. Therefore, old welded and un-welded medium density polyethylene (MDPE) pipes used in Algerian gas distribution systems for up to 29 years were investigated. They were characterized using several techniques including dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Characteristics were compared to un-aged samples which have the same basis material as old ones. The DMA results revealed that the melt viscosity of material at the weld is influenced by ageing while TGA and DSC measurements showed that welds are more sensitive to thermal and oxidative degradation than the rest of the pipes.