LLDPE Geomembrane Liners

Linear low-density polyethylene is a polyethylene copolymer with short, uniform side branches on a linear backbone. That molecular structure is what separates it from HDPE: where HDPE is stiff, strong and vulnerable to stress cracking under sustained deformation, LLDPE yields. Density is 0.939 g/cm³ or lower against roughly 0.94 and above for HDPE, and the practical result is elongation at break of 850 to 900% with multi-axial break resistance of 30% or more. The liner deforms to relieve stress rather than concentrating it at the point of movement.

That behaviour makes LLDPE the standard selection wherever the ground beneath the liner will not stay still. Landfill closure and capping systems sit over waste that consolidates unevenly for decades. Mining applications, seismic zones and construction over poorly compacted or heterogeneous fill present the same problem. In each case a stiffer membrane transfers the settlement into its own material as localised strain, and LLDPE simply follows the ground instead. Multi-axial testing to ASTM D5617 measures precisely this, deformation in every direction at once rather than along a single axis.

The material is supplied in nominal thicknesses from 0.5 to 2.5 mm with a ±10% tolerance, double-sided smooth, in rolls of approximately 7 m width, and is manufactured to meet or exceed GRI GM17, the standard specification for LLDPE geomembranes. Carbon black content is 2.0 to 3.0% with dispersion in categories 1 and 2, and dimensional stability is within ±2% in each direction when tested at 100°C. Special thicknesses are available on request.

Durability is documented rather than asserted. Oxidative induction time is 100 minutes or more to ASTM D3895, and UV performance is measured under GRI GM11 as high-pressure OIT retention after 1,600 hours of accelerated weathering — 20-hour UV cycles at 75°C alternating with 4 hours of condensation at 60°C - with a minimum of 35% retained. Low temperature brittleness is −77°C to ASTM D746. These are the antioxidant depletion and weathering measures that determine how a polyethylene geomembrane ages in exposed service, and they are the reason LLDPE can be specified for exposed applications with a defensible service life expectation.