When materials are exposed to environmental stress factors, ageing and degradation might occur. The adverse effects of exposure to environmental stresses, known as “weathering,” can be seen on materials located both indoors and outdoors.
Degradation due to solar radiation (or sunlight), heat, and humidity are often a concern when organic and polymeric materials such as adhesives are intended for outdoor use. The photochemical effect of sunlight on a polymeric or organic material depends on the absorption properties and the spectral sensitivity of the material. The wavelengths that typically have the most critical effect range from 295-400 nm (ultraviolet radiation, UV). Solar radiation can cause the formation of radicals that can lead to matrix and additive degradation.