The Effect Of Reinforcing Fillers On The UV Light Stability Of Elastomers
The absorption of UV light by the polymer provides the energy to break key molecular bonds, such as C=C, C–H, C=O, near the surface of the exposed coating and create free radicals. These free radicals react with oxygen and form peroxy radicals, which attack the polymer molecules in the coating. The absorption of UV light, therefore, induces both oxidative degradation and crosslinking. Antidegradants are used to protect the polymer against this problem.
Extensive work has been done on the effect of UV light on polymers. However, most of the studies have been concerned with the investigation of the changes that occur in the physical properties of the polymers and are not actually directed at obtaining the details of the microstructures. The selection of antidegradants are mostly based on trial and error without consideration of the possible changes that may occur at the structural level of the polymer, which may cause subsequent undesired changes in coating and adhesive properties.