HD-PE

Polyethylene is the most widely used plastic in the world. Compared with PP, the mechanical properties are even more modest, but so is the price. HD-PE is resistant to chemicals, suitable for food packaging, and withstands cold better than PP.

The look and feel of High-Density Polyethylene and PP are so similar that they may be difficult to tell apart.

Why choose?

  • Inexpensive. HD-PE is a commodity plastic.
  • Good ductility in subzero temperatures (HD-PE has a glass transition temperature of -120°C)
  • Good chemical resistance, even better than that of PP (e.g. petrol canisters are made of HD-PE)
  • High impact resistance

Why not choose?

  • Despite being semi-crystalline, HD-PE has limited resistance against stress cracking.
  • PE is prone to hydrolysis while PP endures hot water better
  • Poor UV-resistance

Typical applications:

  • Bottle caps
  • Toys
  • Sleds
  • Bins (preferably indoor, but commonly used in outdoor applications as well)

By examining the Plasticprop sample made of HD-PE, you can draw for example the following conclusions:

  • The HDPE sample is not very stiff. When knocking on its edge, the sound is low-pitched and similar to that of the PP sample.
  • The surface of HDPE is slightly waxy but very glossy. The surface is soft – this can be determined by scratching it with your fingernail.
  • The filling window shows that HDPE runs well. The integral hinge has filled up and feels credible.
  • The sample is even smaller in dimensions than the PP sample; the shrinkage of HDPE is substantial. The corner effect is present to some extent and the sample’s lower edge is slightly wavy.
  • Considering the low cost of the material, the overall impression of quality is rather good.
  • Spark-eroded draft surfaces are not badly scratched, probably because of the extensive shrinkage.
  • The heat resistance of polyolefins is poor. If you put the HDPE sample in an oven, the heat will reduce its stiffness even further. In a manner typical of semi- crystalline materials, however, HDPE will not collapse –though it becomes very soft when hot, it will preserve and remember its shape.
  • If you put the sample in a freezer, its toughness will not change significantly. HDPE is highly resistant to cold.
  • The density of HDPE is less than 1. Like other polyolefins, the sample floats in water.

Questions, Comments, Feedback

All information on Plasticprop.com is based on the best knowledge and understanding of experienced plastic product designers. Nevertheless, we may be wrong. Do not use this website as your primary or only source of information. Always check and test in practice. Kindly contribute, if you know better. We do not take any responsibility, financial or ethical, for the outcome of your product.