Correlating solubility of chemicals and mixtures with strength of exposed high-density polyethylene geomembrane

Geomembranes in use as liners of landfills and other waste containment stru ctures are subject to both chemical and mechanical attacks. The ability of the geomembrane to maintain its integrity in the face of these attacks is o f major concern in the prevention of discharges from the waste disposal fac ility. In this work, geomembranes were subjected to simultaneous chemical e xposure and mechanical loads using the comprehensive testing system (CTS). The chemicals selected were gasoline and surrogates selected on the basis o f either health-based environmental concern related to the chemical's relea se, or their use in ASTM (American Society of Testing and Materials) testin g of rubbers exposed to gasoline. The thermodynamics of polymer-solvent int eraction, expressed as cohesive energy density, was extended to binary-comp onent mixtures and used to model the change in the mechanical performance o f the geomembrane as measured by the CTS test parameter, Delta E, Delta E. It was found that a volume-fraction based thermodynamic mixing rule for the binary mixtures, consistent with regular solution theory, explained change s in the Delta E of the geomembrane. A nonlinear model provided the ability to predict Delta E as a function of the difference between the cohesive en ergy density of the solvent and the polymer.