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UV Absorber Definition & Classification

 

These additives preferentially take in the incident UV radiation and so protect the polymer from the radiation. UV absorbers don't 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 necessity for high concentrations of additive and thickness of polymer earlier than sufficient absorption will happen to retard the photodegradation effectively.

 

 

However, high concentrations of additive would be uneconomic and technically limited, while many applications (equivalent to polyolefins) are in very thin sections, reminiscent of film and fiber. Benzophenones are good basic-goal UV absorbers for clear polyolefin systems, and can be utilized in pigmented compounds. Benzotriazoles are used primarily in polystyrene. Each will also be used in polyesters. Concentrations are often 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 main perform of UV absorbers is to absorb UV radiation within the presence of a chromophore (Ch) found in the polymer, the goal is to filter out the UV light that's dangerous to the polymer before Ch* has had an opportunity of forming. Above all, a UV absorber must operate within the 290 and 350 nm range.The aim of UV absorbers is to soak up dangerous UV light and quickly transform it into harmless heat. During this process, the absorbed energy is transformed into vibrational and rotational energy of the molecule constituents. For UV absorbers to be effective, it is essential that this process takes place more quickly 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. Crucial UV absorbers are:

 

 

a) 2-(2-hydroxyphenyl)-benzotriazoles

 

b) 2-hydroxy-benzophenones

 

c) hydroxyphenyl-s-triazines

 

d) oxalanilides

 

Every of these UV absorber groups may be characterized by a typical absorption and transmission spectrum.

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