Polystyrene is a versatile polymer resin used in a wide range of applications - especially in the packaging industry.
It is sold in three main forms

• General Purpose Polystyrene (GPPS)
• High Impact Polystyrene (HIPS)
• Expandable Polystyrene (EPS).

The general form is pure polystyrene with few additives and is used when clarity is required even though it is very brittle.

The high impact form is translucent or opaque because of rubber compounds added to the reaction and incorporated into the resin to inhibit crack propagation and hence reduce brittleness.

The expandable form is the same as the crystal form except that low molecular mass hydrocarbons, usually pentane, are incorporated into the finished resin. These additives vaporise during subsequent processing to produce a foam.