2. Production of EPS-M from expandable polystyrene

Expanded polystyrene is obtained from expandable polystyrene after three manufacturing stages:

• pre-expansion or pre-foaming. It is at this stage that the final density is determined;

• ripening and storage. It is at this stage that the pearls rest for several hours to allow them to stabilize;

• molding. This is where the beads are soldered together.

The pre-expansion, ripening and storage operations have three main aims:

• allow surface pentane to disperse in order to reduce the thermosensitivity of pre-expanded pearls during moulding;

• remove excess water from pearls to obtain dry pearls;

• allow time for air to enter the cells to...