Long-term durability of two HDPE geomembranes formulated with polyethylene of raised temperature resistance (PE-RT)

The performance of four 1.5-mm HDPE geomembranes from the same manufacturer each with a different resin and additive package is examined in a synthetic municipal solid waste leachate at five temperatures (40, 65, 75, 85, 95 °C) for 7.5 years. Two geomembranes used polyethylene with raised temperature resistance (PE-RT) resins and two used more conventional polyethylene resins. All four geomembranes were inferred to contain hindered amines stabilizers (HAS) and had very high off-the-roll stress crack resistance (SCR_o) values that decreased to stable, more representative SCR_m values shortly after immersion and it was found that the 3-stage GMB degradation model applied to both Std-OIT and HP-OIT. The time to nominal failure is predicted for a range of temperatures using Arrhenius modelling and the representative SCR_m values. Despite the fact that all four GMBs had similar times to nominal failure at constant elevated temperatures (65–95 °C), it is shown that the HAS used in one of the PE-RT GMBs served a useful function in extending its life in situations such as elevated temperature landfills where there is a time-temperature history to be accommodated by the GMB. The value of considering both Std- and HP-OIT is also demonstrated.