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UV Absorber Definition & Classification
These additives preferentially absorb the incident UV radiation and so protect the polymer from the radiation. UV absorbers do not themselves degrade quickly, however they convert UV energy into hurtless levels of heat energy, which are dissipated throughout the polymer matrix. UV absorbers are limited of their effectiveness because of the physical limitations of the absorption process, and their ability to soak up is ruled by the need for high concentrations of additive and thickness of polymer before enough absorption will happen to retard the photodegradation effectively.
Nevertheless, high concentrations of additive can be uneconomic and technically limited, while many applications (corresponding to polyolefins) are in very thin sections, akin to film and fiber. Benzophenones are good normal-goal UV absorbers for clear polyolefin systems, and can be utilized in pigmented compounds. Benzotriazoles are used mainly in polystyrene. Each can be used in polyesters. Concentrations are normally about 0.25-1.zero%
Synonyms of UV absorber
UV absorber agent
UV stabilizer
UV stabilizer agent
ultraviolet absorber agent
ultraviolet light absorber agent
UV Absorber Classification
The primary operate of UV absorbers is to soak up UV radiation in the presence of a chromophore (Ch) found within the polymer, the goal is to filter out the UV light that is dangerous to the polymer earlier than Ch* has had a chance of forming. Above all, a UV absorber must operate within the 290 and 350 nm range.The purpose of UV absorbers is to absorb harmful UV light and quickly transform it into hurtless heat. Throughout this process, the absorbed energy is transformed into vibrational and rotational energy of the molecule constituents. For UV absorbers to be efficient, it is essential that this process takes place more rapidly than the corresponding reaction within the substrate, and that neither the UV absorber nor the polymer it is intended to stabilize is damaged throughout energy conversion. A very powerful UV absorbers are:
a) 2-(2-hydroxyphenyl)-benzotriazoles
b) 2-hydroxy-benzophenones
c) hydroxyphenyl-s-triazines
d) oxalanilides
Each of those UV absorber groups might be characterized by a typical absorption and transmission spectrum.
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