Polystyrene ignites when exposed to a flame. It burns with a brilliant, sooty flame. The sweet smell that spreads comes from the decomposition of the material and occurs e.g. when cutting foamed polystyrene with the hot wire.
Polystyrene can ignite if it comes into contact with glowing bodies. The most important temperature ranges are as follows:
- Thermal decomposition above 300 ° C
- Development of flammable gases in ignitable concentrations above 350 ° C
- Self-ignition of the decomposition products above 450 ° C
Polystyrene continues to burn after the ignition source has been removed and tends to drip off while burning. Fires can spread quickly this way.
Polystyrene plastics therefore have to be equipped with flame retardants for many applications - especially in the electrical and construction sectors. Flame retardants generally cause the burning material to extinguish rapidly after the ignition source has been removed.