Material discoloration
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We have a certain material that, under normal temperature and pressure and in the absence of light, is a colorless and transparent liquid. However, when exposed to sunlight, a small amount of yellow, viscous oily substance precipitates out, causing the liquid to turn yellow. Could anyone with expertise please explain what might be the cause of this phenomenon or identify the nature of this material? Thank you.
Oxidation should have resulted in the formation of chromophoric groups; you can look up common chromophoric groups and compare them with the components of your material
This post was last edited by qugd on 2015-9-1 at 12:51. If they refuse to even mention the specific names of the materials, what’s there to discuss? Your skin darkens when exposed to the sun, and over time it also produces oil and sweat. The discoloration of your material may also be caused by pigment deposition. Just expose it to less sunlight, or transfer such materials at night; during the day, an umbrella is necessary to shield it from the sun. Such a specific phenomenon requires specific material compositions to be provided.
The materials contain substances that decompose easily when exposed to light
So it must be a substance that decomposes when exposed to light? Generally, the smaller the molecule, the less it absorbs visible light. I think it is due to the formation of strong light-absorbing substances as a result of photochemical reactions, particularly the polymerization and condensation of certain unsaturated substances to form substances with high molecular weights. There are also some substances that result from the formation of oxides due to oxidation.