When you pick up white foam packaging for the first time you are usually struck by how light it is. That’s not surprising when you consider it’s around 95% air. That also gives it excellent insulation properties both in terms of heat and noise.
The white foam is expanded polystyrene or EPS. It’s also often called polystyrene foam. EPS is a lightweight, rigid cellular plastic made from the polymerisation of the styrene monomer. Styrene, a byproduct of crude oil extraction is also found naturally in foods such as strawberries, nuts and beans. The polymerisation process produces translucent spherical beads of polystyrene about the size of sugar granules.
Its exceptional shock-absorbing characteristics make it ideal for the storage and transport of fragile and expensive items such as electronic equipment, chemicals and wines.
Considerable quantities of EPS are also used in the construction industry. EPS is an inert material that does not rot and is not susceptible to attack by pests such as rats or termites. Its strength and durability makes it a versatile building product however it is primarily used as custom insulation in building applications. Products made from EPS include sandwich panels, waffle pods and also void forms. When safety is paramount, EPS comes into its own. It is used in the manufacture of children’s car seats and cycling helmets, where its protective qualities, strength and shock-absorbency are vital.To produce EPS, the polystyrene beads are heated with steam. This causes a pre-foaming agent found within the beads (usually a hydrocarbon such as pentane) to boil. When this happens the beads expand to some 40 to 50 times their original volume. After expansion the beads undergo a maturing period in order to reach an equilibrium temperature and pressure.
The beads are then placed within a mould and reheated with steam. The pre-foamed beads expand further, completely filling the mould cavity and fuse together. The beads are moulded to form boards, blocks or customised products.EPS is used widely as packaging for a variety of products.
