Most polymers have their bond dissociation energies
corresponding to 290–400 nm of wavelengths and hence
are greatly affected by this part of the UV radiation.
Photo-degradation (chain scission and/or crosslinking)
occurs due to the activation of the polymer macromolecule
by the absorption of a photon of light. It is believed that a
definite wave with certain energy in the UV ray may be easily
absorbed by the bond having identical (dissociation)
energy, only the absorbed radiation can be effective in producing
a photophysical process (e.g. bond dissociation) or