Generally, the properties of the polyethylene foams used as cores are:
* Densities from 25 kg/m3 up to 330 kg/m3.
* Semi-rigid to flexible.
* Closed cells.
Examples of applications:
* Panels and sandwich structures for protection of wellhead of oil.
* Multi-layer composites for damping, sometimes in combination with polypropylene foam. Some helmets, for example, are made of thermoplastic skins and a core of one layer of PE foam with, eventually, a second layer of polypropylene foam.
* Crosslinked or linear. Often, the crosslinking improves the mechanical properties and chemical resistance.
Polyethylene foams have:
* Insulating and damping properties.
* Correct mechanical characteristics.
* A low absorption and permeability to the water or the moisture and an excellent hydrolysis behaviour.
* A naturally low fire resistance that can be improved by an adequate formulation.
An interesting development started with Neste and Norsk Hydro is a multi-layer coating for the insulation of high deep-water pipelines.