High Density Polyethylene - HDPE

Polyethylene is a whitish, semi-crystalline, and effectively opaque engineering thermoplastic which, chemically, is a very high molecular weight (3-6 million) HDPE.

As a result, its melt viscosity is extremely high and normally can only be processed by powder sintering methods. Polyethylene has excellent toughness and cut and wear resistance, and also has very good chemical resistance, slightly better than that of HDPE.

Polymer Type

Thermoplastic

Advantages

Advantages of HDPE include good low temperature impact resistance and excellent chemical resistance.

Disadvantages

Disadvantages of HDPE:

  • Susceptible to stress cracking  
  • Has lower stiffness compared to Polypropylene
  • High mould shrinkage and poor UV resistance

Applications

Pipe and pipefittings for water transportation. Toys, bowls, buckets, milk bottles, crates, tanks, containers. Film for packaging. Blown bottles for food.  MDPE (Medium Density Polyethylene) is used for gas pipes and fittings.

Applications include marine quay headings, artificial joints, bearings, gears, and many "wear parts" (eg bottle handling machine components).

Typical Properties

Property Value
Density (g/cm3) 0.96
Surface Hardness SD68
Tensile Strength (MPa) 32
Flexural Modulus (GPa) 1.25
Notched Izod (kJ/m) 0.15
Linear Expansion (/°C x 10-5) 12
Elongation at Break (%) 150
Strain at Yield (%) 15
Max. Operating Temp. (°C) 55
Water Absorption (%) 0.02
Oxygen Index (%) 17
Flammability UL94 HB
Volume Resistivity (log ohm.cm) 17
Dielectric Strength (MV/m) 22
Dissipation Factor 1 kHz 0.0005
Dielectric Constant 1 kHz 2.3
HDT @ 0.45 MPa (°C) 75
HDT @ 1.80 MPa (°C) 46
Material. Drying hrs @ (°C) NA
Melting Temp. Range (°C) 220 - 310
Mould Shrinkage (%) 3
Mould Temp. Range (°C) 30 - 70

Source : Abstracted from Plascams

For more information on Plascams please visit RAPRA Technology Ltd.

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