Hindered amine light stabilizers (HALS) stabilise against weathering by scavenging free radicals that are produced by photo-oxidation of the polymer matrix. UV-absorbers stabilise against weathering by absorbing ultraviolet light and converting it into heat. Antioxidants stabilise the polymer by terminating the chain reaction because of the absorption of UV light from sunlight. The chain reaction initiated by photo-oxidation leads to cessation of crosslinking of the polymers and degradation of the property of polymers. Antioxidants are used to protect from thermal degradation.