LLDPE Geomembranes | GRI-GM17 | Flexibility

LLDPE (Linear Low-Density Polyethylene) geomembranes are highly flexible, durable, and chemically resistant synthetic liners widely used in environmental, geotechnical, and civil engineering applications. With superior stress crack resistance, elongation, and UV stability, LLDPE geomembranes are ideal for landfill liners, ponds, mining containment, and wastewater treatment. Available in thicknesses ranging from 0.5 mm to 3.0 mm, they offer excellent puncture resistance and adaptability to uneven surfaces. Compared to HDPE geomembranes, LLDPE provides greater flexibility, making it suitable for dynamic environments, while meeting international standards such as GRI-GM17, GB/T 17643, ASTM, EN, and ISO for quality and performance. At Metalsin, we supply both smooth and textured LLDPE geomembranes tailored to meet diverse project needs.

What is LLDPE?

LLDPE geomembranes ready to dispatch.

At the microscopic level, Linear Low-Density Polyethylene (LLDPE) is a copolymer of ethylene and alpha-olefins, featuring a linear backbone with short, uniform branches that create a balance between crystalline and amorphous regions, providing flexibility, toughness, and stress crack resistance. Macroscopically, LLDPE exhibits excellent physical properties, including high flexibility, puncture resistance, and durability, making it suitable for applications requiring deformation and heavy-duty use. Its resistance to environmental stress cracking, UV radiation, and chemicals, combined with low permeability to liquids and gases, makes it an effective barrier material for geomembranes, packaging, and containment systems. LLDPE’s ease of processing through extrusion, blow molding, or injection molding further enhances its versatility, enabling its use in a wide range of industrial and consumer products.

Geomembranes: LLDPE, HDPE & LDPE

LLDPE (Linear Low-Density Polyethylene), HDPE (High-Density Polyethylene), and LDPE (Low-Density Polyethylene) geomembranes each have distinct properties suited for different applications. LLDPE geomembranes are highly flexible, with excellent stress crack resistance, elongation, and puncture resistance, making them ideal for dynamic environments, uneven surfaces, and applications requiring deformation tolerance, such as landfill liners and pond liners. HDPE geomembranes, on the other hand, are stiffer and more rigid, offering higher tensile strength and load-bearing capacity, which makes them suitable for high-stress applications like primary landfill liners and tank linings, though they are more prone to stress cracking in certain conditions. LDPE geomembranes are the most flexible and softest of the three, with good chemical resistance and ease of installation, but they have lower tensile strength and are less durable compared to LLDPE and HDPE, limiting their use to less demanding applications. In summary, LLDPE strikes a balance between flexibility and durability, HDPE excels in strength and rigidity, and LDPE offers maximum flexibility but with reduced mechanical performance. The choice among them depends on specific project requirements, including flexibility, chemical resistance, environmental conditions, and load-bearing needs.

GRI-GM17

Linear low-density polyethylene (LLDPE) geomembranes used at the water channel construction site.

GRI-GM17 is a standard specification developed by the Geosynthetic Research Institute (GRI) for Linear Low-Density Polyethylene (LLDPE) geomembranes, covering both smooth and textured surfaces. It outlines minimum physical, mechanical, and endurance properties, including thickness (0.50 mm to 3.0 mm), tensile strength, tear resistance, puncture resistance, and oxidative induction time (OIT) for UV and chemical resistance. The specification ensures manufacturing quality control (MQC) and provides testing methods and frequencies to verify compliance.

Technical Specifications

• Thickness: Ranges from 0.50 mm (20 mils) to 3.0 mm (120 mils) for both smooth and textured surfaces. Thickness tolerance allows for a minimum average thickness with individual values not exceeding -10% of the nominal thickness. Width: Ranges from 2000 mm to 7000 mm. Length: Ranges from 50 m to 150 m.
• Density: Formulated sheet density must not exceed 0.939 g/ml, with the resin density typically ranging from 0.915 to 0.926 g/ml.
• Tensile Properties: Minimum average break strength ranges from 13 N/mm (76 lb/in) for 0.50 mm thickness to 80 N/mm (456 lb/in) for 3.0 mm thickness. Break elongation must be at least 800%.
• Tear and Puncture Resistance: Minimum tear resistance ranges from 50 N (11 lb) for 0.50 mm thickness to 300 N (66 lb) for 3.0 mm thickness. Puncture resistance ranges from 100 N (22 lb) to 600 N (132 lb).
• Carbon Black Content: Must be between 2.0% to 3.0%, with good dispersion to ensure UV resistance.
• Oxidative Induction Time (OIT): Minimum standard OIT is 400 minutes, or 35 minutes for high-pressure OIT, to ensure antioxidant content and long-term durability.
• UV Resistance: LLDPE Geomembranes must retain at least 60% of their OIT after 90 days of UV exposure, ensuring resistance to sunlight degradation.
• Asperity Height (Textured Geomembranes): Minimum average asperity height is 0.40 mm (16 mils) for textured surfaces, enhancing frictional properties.
• Testing Frequency: Properties are tested at specified intervals, such as per roll or per formulation, to ensure compliance with quality control standards.