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Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition.Polymers and particularly plastics are subject to degradation at all stages of their product life cycle, including during their initial processing, use, disposal into the environment and recycling. [1]
This is naturally present in the air at very low concentrations but is exceedingly reactive, particularly towards unsaturated polymers such as rubber, where it causes ozone cracking. The mechanism of ozonolysis is different from other forms of oxidation and hence requires its own class of antioxidant stabilizers.
The toxic effects of UV from natural sunlight and therapeutic artificial lamps are a major concern for human health. Skin surface lipids, including unsaturated lipids such as squalene , sebaleic acid, linoleic acid , and cholesterol can be a subject of oxidation by singlet oxygen and ozone as well as free radicals.
By comparison the dependence of degradation rate on UV exposure and the availability of oxygen is broadly linear. As the oceans are cooler than land plastic pollution in the marine environment degrades more slowly. [40] [41] Materials buried in landfill do not degrade by photo-oxidation at all, though they may gradually decay by other processes.
Other applications, including polycarbonate sheets, may have the anti-UV layer added as a special coating or a coextrusion for enhanced weathering resistance. Polycarbonate is also used as a printing substrate for nameplate and other forms of industrial grade under printed products. The polycarbonate provides a barrier to wear, the elements ...
A plastic bucket used as an open-air flowerpot photodegraded after some years. Photodegradation is the alteration of materials by light. Commonly, the term is used loosely to refer to the combined action of sunlight and air, which cause oxidation and hydrolysis. Often photodegradation is intentionally avoided, since it destroys paintings and ...
The prediction of the ageing of plastic materials is a subject that concerns both users and manufacturers. It covers plastic materials (polymers, fillers and various additives) or intermediates that are the transformers that use their thermoplastic property for the manufacture of objects by processes such as extrusion, injection molding, etc.
This effect is a response of the skin called erythema, which is caused by a sufficient strong dose of UV-B. The Sun's UV output is divided into UV-A and UV-B: solar UV-A flux is 100 times that of UV-B, but the erythema response is 1,000 times higher for UV-B. [ citation needed ] This exposure can increase at higher altitudes and when reflected ...