page_title: UV degradation
section_title: Detection
hierarchical_section_title: UV degradation / Detection
caption_attribution_description: English: own spectrum from casebook
context_page_description: Many natural and synthetic polymers are attacked by ultraviolet radiation, and products using these materials may crack or disintegrate if they are not UV-stable. The problem is known as UV degradation, and is a common problem in products exposed to sunlight. Continuous exposure is a more serious problem than intermittent exposure, since attack is dependent on the extent and degree of exposure.
  Many pigments and dyes can also be affected, and the problem known as phototendering can affect textiles such as curtains or drapes.
context_section_description: The problem can be detected before serious cracks are seen in a product using infrared spectroscopy, where attack occurs by oxidation of bonds activated by the UV radiation forming carbonyl groups in the polymer chains.
  In the example shown at left, carbonyl groups were easily detected by IR spectroscopy from a cast thin film. The product was a road cone made by rotational moulding in LDPE, which had cracked prematurely in service. Many similar cones also failed because an anti-UV additive had not been used during processing. Other plastic products which failed included polypropylene mancabs used at roadworks which cracked after service of only a few months.
caption: IR spectrum showing carbonyl absorption due to UV degradation of polyethylene
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