2. Polymerization processes

2.1 Process principles

Polystyrene has been manufactured on an industrial scale since the 1930s in the USA and Germany.

Three processes are currently in use.

• Radical suspension polymerization

Polymerization takes place in suspension in water. This is a discontinuous process, requiring the handling and treatment of large quantities of water. It is only used for expanded polystyrene, ABS and certain special polystyrenes (very high molecular weight, or impact polystyrene using EPDM rubber).

• Anionic solution polymerization

Polymerization takes place in solution in a hydrocarbon solvent; the reaction is...