Expanded Polystyrene (EPS) is a lightweight, rigid, plastic foam insulation material produced from solid beads of polystyrene. When the pearl-shaped raw material is brought into contact with steam it expands to around 40 times its original size. It can then be moulded into appropriate forms suited to their application. This means that EPS consists largely of air.
98 percent to be exact.
Who needs EPS?
Anyone who needs to thermally and acoustically insulate walls, roofs or floors will find EPS the ideal, cost-effective and easy-to-use material in all types of buildings, from houses and offices to factories and schools. EPS is used by civil engineers as a lightweight fill or void-forming material. It is also used as a flotation material.
How is EPS produced?
Interested to find out more about the production of EPS, take a look at this video.
The manufacture of EPS conforms to the most stringent health and safety requirements in Europe.
There are 5 manufacturing stages:
- Pre-expansion: Polystyrene granules are expanded by free exposure to steam to form larger beads, each consisting of a series of non-interconnecting cells.
- Conditioning: After expansion, the beads still contain small quantities of both condensed steam and pentane gas. As they cool, air gradually diffuses into the pores, replacing, in part, the other components.
- Moulding: The beads are moulded to form boards, blocks or customised products. The mould serves to shape and retain the pre-foam, and steam is again used to promote expansion. During moulding, the steam causes fusion of each bead to its neighbours, thus forming a homogeneous product.
- Shaping: Following a short cooling period, the moulded block is removed from the machine, and after further conditioning, may be cut or shaped as required using hot wire elements or other appropriate techniques.
- Post-production processing: The finished product can be laminated with foils, plastics, roofing felt, fibreboard or other facings such as roof or wall cladding material.
The properties of EPS insulation materials for buildings and their test methods are defined in EN 13163, which is mandatory since 13 May 2003 for all EU countries. EN 14933 is the relevant standard for civil engineering applications. Further standards are under development, such as for installed equipment. These harmonised European standards include of a list of properties and test methods, both for general and for specific applications.
The manufacturer declares the properties of the specified product, and is allowed – after initial type testing by a notified body and taking into regard the conformity rules in EN 13172 – to put CE marking on the product. Compliance with 'local' building regulations is based on the performance level of the finished product and determined individually by each EU country.
An overview of a number of EPS properties per EPS type according to EN 13163 is given in the following table. For specific applications the producers are prepared to develop product types that suit these applications perfectly.
EPS product types without intended specific application ("commodity")
|EPS Type||EN 13163||[unit]||EPS 60||EPS 100||EPS 150||EPS 200||EPS 250|
|Thermal conductivity||EN 12667 or EN 12939||λ [mW/(m·K)]||38||36||35||34||34|
|Compressive stress 10 %||EN 826||CS(10) [kPa]||60||100||150||200||250|
|Bending strength||EN 12089||BS [kPa]||100||150||200||250||350|
|Dimensional stability||EN 1603||DS(N) [%]||0,5||0,5||0,5||0,5||0,5|
|Approximate density||ρ [kg/m³]||15||20||25||30||35|