Antioxidant depletion from a 2 mm HDPE geomembrane used in brine containment

The depletion of antioxidants from a 2 mm high-density polyethylene geomembrane immersed in brine at seven temperatures (95, 85, 75, 65, 55, 40, and 25°C) for 28 months is reported. An Arrhenius model is used to predict the performance of the geomembrane at low site-specific temperatures. The antioxidant depletion times are reported for temperatures between 20 and 95 o C. The solubility of the antioxidant and stabilizer packages, the oxidation by-products, and their susceptibility to hydrolysis are discussed. After 28 months of incubation, no oxidative degradation was observed for samples in the full brine solution even at 95 o C. Morphological changes reduced the stress-crack resistance to a stable representative value without a reduction in the tensile elongation at break. The effect of the brine solution concentration on the depletion of antioxidants and stabilizers was investigated at 85°C. It was found that the depletion rate decreases with the increasing brine concentration.