Chemistry
Mechanisms of Photodegradation of Polymers and Stabilization Strategies
Quick fact
Ultraviolet light with wavelengths between 290–400 nm carries enough energy to break the weakest carbon–carbon and carbon–hydrogen bonds in most polymers. The resulting radical chain reactions can cause a polyethylene film to lose 90% of its elongation at break within just a few months of outdoor exposure.
Why this is interesting
You may have noticed that an old plastic lawn chair left in the sun becomes brittle and faded. Why does sunlight, which gives life to plants, also destroy plastics?