When plastics are exposed to UV rays, the polymer chains are broken and radicals are formed. These radicals react with oxygen in the air to become peroxide radicals, which successively break the polymer chains, causing further degradation.
UV absorbers prevent the formation of radicals by absorbing UV light and converting it into more stable energy which is then released. They also prevent decomposition of organic substances contained in resins.
Light stabilisers prevent successive degradation by scavenging generated radicals.
Antioxidants stabilise peroxide radicals formed as a result of the radicals reacting with oxygen in the air.
