What types of material photodegrade?

Answer 1

Photosensitive materials have their chemistry changed by light. The most energetic light is that pesky short wavelength ultraviolet or UV light. It tends to take weak covalent bonds apart if it can. Any material with weak covalent bonding may be subject to photodegradation. There are any number of materials - or components of materials - that fall into this group. As a group, the polymers, plastics composed of long chain molecules, have a number of different flavors that can get hammered by UV radiation. Many plastics will stand up to sunlight (specifically the UV) fairly well, and automotive paint is just one of them. And pollution (particularly oceanic polution) by plastics is reaching monumental proportions because the materials hang around so long. But as a group, the polymers take a beating when the energy in the UV rays that pound the material break chemical bonds and destroy the integrity of the material. We've seen what sun does to a plastic grocery bag. The most photosensitive materials are photographic films. But they are designed to do what they do in the specific way that they do it. They could easily be classified as the material most sensitive to photodegradation.