Fundamental Degradation Processes Relevant to Solar Irradiation of Cellulose: ESR Studies

The objective of this work was to study the effect of solar radiation on cellulose by means of ESR techniques. It is shown by ESR spectra that outdoor exposure of cellulose to concentrated sunlight, regardless of the presence of oxygen and sensitizer, causes the polymer to degrade via free-radical processes. Particularly, it is shown that main-chain scission occurs under solar radiation. This phenomenon is accompanied by the formation of peroxide when oxygen is present. It is also revealed that photooxidation leads ultimately to discoloration of the polymer at exposed surfaces.