| POLYETHYLENES (Click for Properties & Specs) Back to the Materials Group main page. Polyethylenes are semi-crystalline materials with excellent chemical resistance, good fatigue and wear resistance, and a wide range of properties (due to differences in length of the polymer chain.) Polyethylenes are easy to distinguish from other plastics because they float in water. Polyethylenes provide good resistance to organic solvents, degreasing agents and electrolytic attack. They have a higher impact strength, but lower working temperatures and tensile strengths than polypropylene. They are light in weight, resistant to staining, and have low moisture absorption rates. Low Density Polyethylene (LDPE): This extruded material offers good corrosion resistance and low moisture permeability. It can be used in applications where corrosion resistance is important, but stiffness, high temperatures, and structural strength are not. A highly flexible product, LDPE is used widely in orthopaedic products, or where mobility without stress fatigue is desired. LDPE is also frequently used in comsumer packaging, bags, bottles, and liners. High Density Polyethylene (HDPE): Representing the largest portion of the polyethylene applications, HDPE offers excellent impact resistance, light weight, low moisture absorption, and high tensile strength. HDPE is also non-toxic and non-staining and meets FDA and USDA certification for food processing. Ultra High Molecular Weight Polyethylene (UHMW PE): Light weight (1/8 the weight of mild steel), high in tensile strength, and as simple to machine as wood, UHMW PE is the ideal material for many wear parts in machinery and equipment as well as a superb lining in material handling systems and storage containers. UHMW PE is self-lubricating, shatter resistant, long-wearing, abrasion and corrosion resistant. It meets FDA and USDA acceptance for food and pharmaceutical equipment and is a good performer in applications up to 180 °F (82 °C) or when periodically cleaned with live steam or boiling water to sterilize. |
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| NOTE: All values are average test results from typical production material. No warranty is implied or guaranteed and testing is recommended for each application. |
ASTM or Property LDPE HDPE UHMW
UL Test
PHYSICAL
D792 Density (lb/in³) 0.033 0.035 0.034
D792 Density (g/cm³) 0.92 0.95 0.93
D570 Water Absorption, 24 hrs (%) <0.01 0 0
MECHANICAL
D638 Tensile Strength (psi) 1,800-2,200 4,600 3,100
D638 Tensile Modulus (psi) - - 125,000
D638 Tensile Elongation at Yield (%) 600 900 -
D790 Flexural Strength (psi) - - -
D790 Flexural Modulus (psi) - 200,000 125,000
D695 Compressive Strength (psi) - - 2,000
D695 Compressive Modulus (psi) - - -
D785 Hardness, Shore D D41-D50 D69 D62-D66
D256 IZOD Notched Impact (ft-lb/in) No Break 3 No Break
THERMAL
D696 Coefficient of Linear Thermal
Expansion(x 10-5 in./in./°F) - - 1.11
D648 Heat Deflection Temp (°F / °C)
at 66 psi 110/38 - 203/95
at 264 psi - - -
D3418 Melting Temperature (°F / °C) - - -
- Max Operating Temp (°F / °C) 160 / 71 180 / 82 180 / 82
C177 Thermal Conductivity
(BTU-in/ft²-hr-°F - - 2.9210.06
(x 10-4 cal/cm-sec-°C) - - 10.06
UL94 Flammability Rating n.r. n.r. H-B
ELECTRICAL
D149 Dielectric Strength (V/mil)
short time, 1/8" thick - - 2,300
D150 Dielectric Constant at 50 kHz - - 2.3
D150 Dissipation Factor at 50 kHz - - 0.0002
D257 Volume Resistivity (ohm-cm) at 50% RH - - >5 x 1016
D495 Arc Resistance (sec) - - -
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