Polyolefin comparison

There are four polyolefins that can be used for geomembranes. All four have a set of shared properties, as well as specific properties that determine their suitability for different applications.

HDPE

High-density polyethylene

HDPE has become the de facto standard for environmental protection, including landfills, landfill capping and in general all applications that require three fundamental properties: maximum chemical resistance, maximum resistance against the elements (UV radiation and ageing caused by thermal cycles in the atmosphere) and impermeability to the majority of the gases that often accompany the products being contained.

HDPE’s specific properties also make it the best product for water storage and hydraulic engineering, such as channels, lagooning, golf course ponds and aquaculture.

VLDPE

Very low-density polyethylene

VLDPE is naturally extremely flexible, offering maximum weldability and workability, albeit at the cost of the loss of some UV resistance and offering almost no chemical resistance and gas impermeability.

VLDPE is considerably more expansive than HDPE and is used for geomembranes that need to be fitted to vertical walls, tight angles, bottoms and projections in the construction where a high level of flexibility is required.

LLDPE

Linear low-density polyethylene

LLDPE offers a middle ground between HDPE and VLDPE and is used for a wide range of mid-flexibility products, from high-spec materials with high chemical resistance suitable for environmental applications, through to products that lack chemical resistance and are only suitable for water storage with specific restrictions. Resistance to UV radiation and ageing cycles also varies widely between the two ends of the spectrum but is on average 30% less than HDPE.

PP

Polypropylene

Polypropylene (PP) offers a high level of flexibility, despite being less weldable than VLDPE, and high chemical resistance, largely similar to HDPE. This makes the material suitable for protecting against corrosion or tank and reservoir storage of specific products, aggressive chemicals, corrosive substances and contaminants in general where a flexible product is required.