New Trends in the Photochemistry of Polymers

Polymer science is, of course, driven by the desire to produce new materials for new applications. The success of materials suchas polyethylene, polypropylene, poly(vinyl chloride) and polystyrene is such that these materials are manufactured on a huge scaleand are indeed ubiquitous.It is widely recognized that ultraviolet rays in sunlight (wavelengths between 280 nm and 400 nm) is an important factorcausing photodegradation to some organic substances such as polymers.UV radiation causes photooxidative degradation which results in breaking of the polymer chains, produces free radical and reducesthe molecular weight, causing deterioration of mechanical properties and leading to useless materials, after an unpredictable time.In order to protect against the damaging effects of UVR on polymers, addition of UV light absorbers, excited state quenchers,hindered amine light stabilizers (HALS), hydroperoxide decomposers, radical scavengers, pigments, fillers and antioxidants are aneffective and convenient solution in practice.