Polyethylene can fail by slow crack growth from stress raisers such as scratches, grind marks, seam edges and folded wrinkles. Resistance is measured with a notched constant tensile load test, which records how long notched specimens survive at a fraction of yield stress, and specs set a minimum time in hours. Good resin and careful seaming, without deep grinding or overheating, keep the risk low.
Cracks are running out from the grind marks along the extrusion seams, classic stress cracking in old sheet.
Also heard as
- environmental stress cracking
- ESC
- slow crack growth
Related terms
HDPE
High-density polyethylene: the stiff, chemically resistant polymer used for most landfill and mining geomembranes.
Grinding
Lightly abrading geomembrane before an extrusion weld to remove the oxidized surface and dirt.
OIT
Oxidative induction time: a measure of how much antioxidant protection remains in a polyolefin geosynthetic.
Extrusion weld
Geomembrane seam made by laying a bead of molten polymer along the edge of an overlap, used for patches and details.