EFFECTS OF THICKNESS ON THE AGEING OF HDPE GEOMEMBRANES MADE FROM THE SAME RESIN

By: Amr Ewais

High density polyethylene (HDPE) geomembranes (GMs) are widely used as a barrier in different geoenvironmental and geotechnical applications. During their service life, it can be expected that the HDPE GMs will age and eventually experience a degradation of their chemical and physical properties.  This study investigates the effect of thickness on the depletion of antioxidants from HDPE GMs in accelerated aging tests. A testing program was performed on four HDPE GMs having nominal thickness of 1.0, 1.5, 2.0 and 2.4 mm. The GMs were made from the same polymer and had the same additives. The GMs were aged in synthetic leachate at five different temperatures (26, 40, 55, 70 and 85oC). The oxidation induction time (OIT) was monitored and was used to represent the depletion of antioxidants from the GMs. The results showed that the depletion rate of the antioxidant from HDPE GMs is inversely proportional to their thickness, with thicker GMs likely having a longer service life (other things being equal).