High-density polyethylene

HDPE (high-density polyethylene) is one of the most used plastics on the planet, it’s got a high strength to weight ratio and is perfect for contact with food.

Strength Durability Hardness Weight
4 out of 5 stars (4 / 5) 4 out of 5 stars (4 / 5) 3 out of 5 stars (3 / 5) 4 out of 5 stars (4 / 5)
Elasticity Flexibility Fabrication Availability
2 out of 5 stars (2 / 5) 3 out of 5 stars (3 / 5) 5 out of 5 stars (5 / 5) 5 out of 5 stars (5 / 5)


Good strength to weight ratio, food safe, good chemical resistance, stable up 110°C, particularly good for blow moulding, translucent finish, can be shaped by many processes, can easily be recycled.


High thermal expansion, does not bond well (bad for gluing), can crack along stress lines, poor UV resistance

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balancebike_grey-600x630Both the title image and this bike are made by loll designs who make outdoor furniture and children’s toys out of recycled HDPE due to it’s durability

image from “http://www.wrap.org.uk/”

HDPE is low cost and has good chemical resistance making it suitable for not only milk but also for strong cleaners like bleach. 
helmet1HDPE has good impact absorption and is used in helmets and other safety gear. It is also very rigid allowing it to retain it’s shape.


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Advantages of HDPE?

Easy to recycle

  • HDPE is very easy to recycle there is also a lot of it produced.
  • Polyethelene is a thermoplastic means it can be heated and reshaped, however every melting process will degrade in quality to a certain degree.
  • It’s eco friendly to reuse saving enough energy to power a 60 watt light bulb for six hours [source: recycle-more.co.uk]

Blow moulding

  • HDPE suits blow moulding as it’s resistant to cracking and doesn’t warp easily.
  • Very good level of infrastructure supporting blow moulding of HDPE
  • Even when the material is thin as commonly happens in blow moulding HDPE has a good level of stiffness

Disadvantages of HDPE

High Thermal expansion

  • The video shows the effects that thermal expansion has on a metal ball.
  • Makes HDPE unsuitable for projects with high degree of precision.


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