Aging effect on thermal, mechanical and tribological behaviour of polymeric coatings used for pipeline application

Aging process of polymeric coatings used for pipeline application is a progressive phenomenon which involves several mechanisms. In fact, the use of these coatings in a variety of aggressive environments affects progressively their lifetime especially at long term. To simulate the behaviour of such coatings during aging time, accelerated weathering conditions are required. In this work, a polymeric coating based on high density polyethylene (HDPE) was immersed in synthetic sea water and in distilled water at a set temperature of 70 °C. Aging effect on physico-chemical, mechanical and tribological properties of this coating was undertaken. Firstly, sorption kinetic was studied through water absorption rate response. Therefore, diffusion coefficients of solvent molecules in the coating specimens were determined. differential scanning calorimetry (DSC) analysis shows that the glass transition temperature ( T g) decreases with immersion duration due to the solvent plasticization effect. Degradation of mechanical properties was also observed. In fact, elastic modulus and tensile strength were decreased by hygrothermal aging. Similarly, coatings surface properties were also affected. Wear resistance of immersed specimens was decreased compared with unaged ones.