What are the advantages and disadvantages of rigid polystyrene?

Pure solid polystyrene is a colorless, hard plastic with limited flexibility. It is a by-product of petroleum refinement and has been in widespread use following WW2.

Advantages

It can be cast into molds with fine detail.

It can be transparent

Can also be coloured.

Very economical

Can be aerated (with CO2) to make Excellent insulator

Can be foamed between card to make lightweight rigid panels

In its various forms it is usually easy to work

It is versatile -uses range from cutlery to explosives

Can be recycled - thermoplastic so can be remoulded indefinitely

Disadvantages

Older types of Expanded polystyrene contain CFCs

Flammable (especially if oil painted)

It takes a long time to decompose and is regarded as a pollutant -eg McDonalds packaging

Expanded foam is uneconomical to collect for recycling

Poor resistant to organic solvents.