EPP (Expanded Polypropylene Foam)
Sitting snugly in the negative space between the cardboard box and the product lies a low-density and solid material that, though often used for packaging, has a much more valuable range of uses outside the short life of packaging.
The unique quality that expanded polypropylene has to offer the world of materials is its aerated structure, which can be controlled to a range of densities to achieve lightweight but thick, solid blocks. Its big disadvantage is that, like expanded polystyrene (EPS), its main application, and the one that is most visible, is in cheap, transient packaging materials. Although polystyrene and polypropylene are not the only materials that can be foamed, they deserve special attention because they are so prolifically used.
There are comparisons to be made between EPP and EPS, one of which is the ability they both have to be formed into large, solid wall thicknesses. EPP can also be coloured, printed with surface patterns, and graphics can be moulded into the surface. It can also be made available with different colour combinations in the same components, giving a mottled, multicoloured effect. Apart from stand-alone components and products, manufacturers have also developed technology where EPP can be moulded directly into the casings of other components, reducing assembly times and costs. EPS is much less brittle, offering a higher degree of flexibility, but can also be formulated to be much harder.
Image: GÜ packaging
Key features
•Inexpensive
•Lightweight
•Excellent energy absorption
•Variable densities
•Good thermal insulation
•Can be coloured
•Recyclable
Sources
Widely available from multiple suppliers.
Cost
Comparatively low cost.
Sustainability issues
As with other aerated/ expanded forms of plastics, the advantages they offer in relation to reduced use of materials is offset against the issue of the waste that these materials generate and the difficultly in disposing of such bulky items.
Production
The components are formed in male and female aluminium mould tools, with steam introduced from behind each half of the tool.
A good combination of properties make this prolific material useful for a massive range of applications, including surfboards and bicycle helmets, fruit and vegetable trays, insulation blocks, head impact protection in car head rests, bumper cores, steering column fillers and also acoustic dampening. EPP can also incorporate in-built springs for extra protection in packaging.
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–Inexpensive –Lightweight –Durable –Widely available –Recyclable |
–Generates a lot of waste, which is difficult to dispose of |