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Perhaps surprisingly, the effect of temperature is often greater than the effect of UV exposure. [5] This can be seen in terms of the Arrhenius equation, which shows that reaction rates have an exponential dependence on temperature. By comparison the dependence of degradation rate on UV exposure and the availability of oxygen is broadly linear.
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.
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]
Accelerated aging is testing that uses aggravated conditions of heat, humidity, oxygen, sunlight, vibration, etc. to speed up the normal aging processes of items. It is used to help determine the long-term effects of expected levels of stress within a shorter time, usually in a laboratory by controlled standard test methods.
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 .
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 ...
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This reduces the absorption of UV rays by the polymer matrix and hence reduces the rate of weathering. Phenolic benzotriazoles (e.g. UV-360, UV-328) and hydroxyphenyl-triazines (e.g. Bemotrizinol) are used to stabilise polycarbonates and acrylics, [25] oxanilides are used for polyamides and polyurethanes, while benzophenones are used for PVC.