UV

Ultraviolet radiation that reaches the earth's surface has a wavelength range of 290-400nm. This coincides with the bond dissociation energy of most organic polymers. The degradation of polymers exposed to UV results from a series of complex processes. The polymer absorbs the UV radiation and bond dissociation is initiated leading to chain scission and/or crosslinking. In addition to this the presence of oxygen can lead to the formation of some functional groups such as: carbonyl (C=O), carboxyl (COOH) or peroxide (O-O).

UV degradation generally only affects the surface of a composite, however, the resultant flaws in the surface layer can provide a point of initiation for fracture.