Protection against UV degradation

Reasons for use coloring, protection against UV degradation (carbon black and titanium dioxide)... 

Polyethylene is subject to degradation by UV radiation. If exposed outdoors, carbon black must be added to the formulation for protection against UV degradation. 

The incorporation of UV stabilizer is necessary for protection against UV degradation. Enhanced UV light stability can affect the color stability and the mechanical properties of plastics. UV stabilizers protect PE from damage by sunlight in outdoor environments. Similarly, carbon black in PE mulch film protects and blocks the penetration of radiation. 

Stabilizers. Antioxidants provide protection against UV light and thermal oxidative degradation. Hindered phenols are the most common nonstaining antioxidants. For SBR latices, two additional type of stabilizers must be used. 

A further consequence of our photocatalytic oxidation cycle is the protective function which rutile pigments exert against UV degradation. This effect can be shown by several methods ... 

Opaque Stains. Solid color or opaque stains are another classification of finishes sometimes inaccurately described as natural wood finishes. These finishes are high in pigment content and completely mask the color and figure of the wood. Surface texture is retained and these finishes yield a flat appearance. They do protect wood against UV degradation, but tend to perform more like paints in that they do not penetrate the wood surface to any degree. 

Because UV degradation along with heat creates the same—by nature—free radicals, as the heat alone (see above), the same antioxidants as described above can be used for board protection against oxidative degradation. In other words, it does not matter what causes free radicals, heat or UV light When free radicals got into bulk of the composite board and propagate there, antioxidants stop them there, provided that antioxidants are used in sufficient amounts. 

Products of degradation - photo-Fries rearrangement producing UV absorber which protects against further degradation ... 

Compared to polycarbonate, polyarylates often exhibit better gloss behavior, less deposit formation, and better transparency. Moreover, the mechanical properties of polyarylates are less impaired than those of polycarbonate [83]. Coating with polyarylate is often recommended in order to protect polycarbonate against UV degradation [572]. 

Pigments are usually added to impart a particular decorative eolor. They also help protect the binder against UV degradation fi-om outdoor exposure. The minerals added to extend pigments, modify film properties and reduce cost are also commonly refered to as pigments or extender pigments in coatings formulation. 

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