Expanded polystyrene or EPS

Expanded polystyrene (EPS) is a rigid, low-density alveolar material, mainly used for thermal insulation in buildings and for packaging industrial and food products.

There are two types of expanded polystyrene:

• molded expanded polystyrene (PSE-M) ;

• extruded polystyrene foam (PSE-E) or XPS (Extruded polystyrene foam).

EPS-M is obtained from crystal polystyrene to which a blowing agent (pentane, C ₅ H ₁₂ ) has been added during polymerization.

EPS-E is obtained during extrusion by injecting an expansion gas (pentane) under pressure into the molten crystal polymer.

The most outstanding properties of expanded polystyrene are :

• its low density;

• thermal insulation ;

• excellent mechanical properties (compressive strength, shock absorption);

• its insensitivity to water;

• its ease of shaping (molding, cutting);

• recyclability.

Last but not least, the large-scale production of styrene and the ease with which this monomer can be polymerized make it a particularly attractive property/price compromise for the two main markets for expanded polystyrene.