The use of High Density Polyethylene (HDPE) lining in seepage prevention in dams was identified to reduce the cost of water storage. To make it acceptable to end users, it is necessary to determine its lifespan when exposed to tropical climates using viscoelastic models. The Findley Power Law was used to build a model for prediction of the material behaviour at elevated temperature in both short term and long term applications. Time-Temperature Superposition (TTSP) was also used to develop master curves for prediction of long term properties. Micrographs were presented to track the changes...