In some geotechnical applications a geomembrane may be exposed for varying periods where UV (ultraviolet) radiation and elevated temperature cause degradation of geomembrane in a free radical oxidation mechanism. In this paper, the effect of UV (ultraviolet) exposure on HDPE (high density polyethylene) and f-PP (flexible polypropylene) geomembranes is evaluated. The results of density, carbon black content (CBC) tensile properties, Melt Flow Index (MFI) and Oxidation Induction Time (OIT) (both Standard-OIT and High Pressure- OIT) are discussed. An increase in density implies increase in brittleness and a slight decrease in CBC implies the effectiveness of carbon black to prevent photo-oxidation. Although tensile properties of the exposed samples remained unchanged, the depletion of antioxidants was found higher for f-PP than for HDPE. There was no significant difference between the MFI value of the virgin and exposed HDPE GM samples but a decrease in MFI was found in f-PP GM that signifies that cross-linking has occurred.
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