Introduction To Polymeric Geomembranes

Classifications For Common Geomembrane Types

It is important to know there are hundreds of different applications that require a liner system.  The large number of commercially available geomembranes (or polymeric geosynthetic barriers) can make it challenging to select which geomembrane has the most appropriate combination of performance properties for a given application.  Each type of geomembrane material has different characteristics that affect its installation procedures, durability, lifespan and overall performance. It is therefore necessary to match the project performance criteria with the right combination of properties of a particular geomembrane.

Geomembrane materials are generally selected for their overall performance in key areas of chemical resistance, mechanical properties (elastic modulus, yield strength, puncture/ tear resistance), weathering resistance, product life expectancy, installation factors and cost effectiveness.

The properties of polymeric geomembranes are determined mainly by their polymer structure (architecture of the chains), molecular weight (the length of the chains) and the crystallinity (packing density of the chains).  Polymer crystallinity is one of the important properties of all polymers.  Polymers exist both in crystalline and amorphous forms.

Common geomembranes can be classified into two broad categories depending on whether they are thermoplastics (i.e. can be remelted) or thermoset (cross linked or cured and hence cannot be remelted without degradation) (see table).  Since thermoset geomembranes are cross linked, they can exhibit excellent long-term durability.

When selecting a geomembrane for a particular application the following aspects need to be considered:

  • Choice of polymer
  • Type of fabric reinforcement
  • Color of upper ply (white to maintain lower temperatures for sun exposed applications)
  • Thickness
  • Texture (smooth or textured for improved friction angles)
  • Product life expectancy
  • Mechanical properties
  • Chemical resistance
  • Ease of installation

Main Plastic Classifications For Common Geomembrane Types

Thermoplastic geomembranes Thermoset geomembranes Combinations of thermoplastic and thermoset
HDPE, LLDPE, fPP, PVC, EIA, TPU, PVDF CSPE (crosslinks over time)
EPDM rubber
Nitrile rubber
Butyl rubber

Polychloroprene (Neoprene)

PE-EPDM

PVC (nitrile rubber)

EPDM/TPE
Polymer-modified bitumen

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2 Responses to “Introduction To Polymeric Geomembranes”

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