Short for high-density polyethylene, specified at a density of at least 0.940 g/cm3 for geomembranes. It resists a wide range of chemicals and, with 2 to 3 percent carbon black, ultraviolet light, and it is seamed by fusion and extrusion welding. Its weak points are stiffness, large thermal expansion that makes wrinkles, and stress cracking when resin or workmanship is poor.
Sixty-mil HDPE on the floor, textured on the slopes, and the seamers want it done before the afternoon waves.
Black HDPE in the sun moves a lot: a 100 meter panel can grow by half a meter or more between a cold morning and a hot afternoon.
Also heard as
- high-density polyethylene
- HDPE liner
- poly
Related terms
Geomembrane
Low-permeability polymer sheet used as a liquid or gas barrier in liners, covers, ponds and tunnels.
LLDPE
Linear low-density polyethylene: a softer, more flexible geomembrane polymer that follows uneven ground better than HDPE.
Stress cracking
Brittle cracking of polyethylene geomembranes under long-term tension well below their yield strength.
OIT
Oxidative induction time: a measure of how much antioxidant protection remains in a polyolefin geosynthetic.
Waves
Installer word for the wrinkles that form in a geomembrane as it expands in the sun.