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Low-Density PE Foam Classification

November 04, 2019


Low-density polyethylene foam (PE foam) is used for a large range of industrial uses – with the most common applications in protective packaging, thermal insulation, construction, surface protection, sports, sound and cushioning absorption, and automobile industries.


It’s clear that PE foam is essential for many of the applications we look past on a daily basis. But where does it come from? – and are there different types of low-density PE foams commonly used?


Today we’ll bring it back to basics as we discuss origins of polyethylene and various major classifications of low-density polyethylene foam.


Where does PE foam come from?


As its name suggests, PE foam is composed of polyethylene – one of the most commonly used plastics world-wide. The first unstable version of polyethylene was synthesized by German chemist Hans Von Pechmann in 1899 – known as polymethylene. It wasn’t until 40 years later, in 1933 that English chemists Eric Fawcett and Reginald Gibson synthesized the first industrially practical polyethylene variant. During WWI and WWII, more research was conducted to develop polyethylene into a commercially distributable version of polyethylene.


Polyethylene Classifications


Polyethylene plastic variants are classified by density and branching. Within polymer chemistry – branching refers to the replacement of a substituent – resulting in differing mechanical properties based on the extent and type of branching.

Common polyethylene plastic classifications include ultra-high molecular weight polyethylene (UHMWPE), ultra-low molecular weight polyethylene (ULMWPE), and high molecular weight polyethylene (HMWPE).


Foam-Variant Classifications


Foam variants are also classified based on density. Many industrial applications favour low-density foam variants due to their unique properties. Low-density foams are less rigid and more flexible than higher density foam types. For the purpose of this blog we will focus on major classifications of low-density PE foam. If you’re interested in learning more about the mechanical benefits of PE foam read our previous blog Understanding the Properties of Polyethylene Foam.  

There are essentially two types of low-density PE foams: extruded and cross-linked. Extruded foams are manufactured using a continuous process by blending the polyethylene polymer with a foaming agent in a high pressure environment. Cross-linked foams can be manufactured via continuous processes and by batch.