Methods of testing PEX plastics: Ultraviolet radiation
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All components of solar radiation in one way or another, have harmful effects on the plastic. In the most severe degree of degradation occurs under the ultraviolet. The energy of ultraviolet radiation sufficient to break the inter atomic bonds. This effect on the macromolecules contributes thermal oxidant degradation, which leads to belittlement, fading colors and a decrease of all mechanical and electrical properties of the material. To model the radiation in the same spectrum used Xenon lamp fluorescent radiation, solar lamps and other artificial sources of radiation, which also emit effects harmful to polymers. Other factors that influence the environment, such as heat, humidity, oxygen, increase the destructive processes caused by ultraviolet radiation.
One of the most effective ways to protect the polymer from ultraviolet radiation is the introduction of the material adsorbers of UV radiation or stabilizer. Such additives can effectively absorb much of the material entering the UV radiation and dissipate the absorbed energy without much harm to the polymer. Thus, the polymer is protected from the action of ultraviolet radiation due to its absorption of special absorber, which is spent in time. For that purpose has developed various types of both organic and inorganic absorbers of UV radiation. Almost all inorganic pigments in varying degrees, absorb ultraviolet radiation, thus protecting the material. Apparently, the most effective pigment of this type are some types of carbon, which absorbs energy from ultraviolet and visible light in almost the entire frequency range and converts it into relatively harmless radiation.
Stabilizers, in contrast to the absorbers of UV radiation, prevent the destruction of chemical bonds, or convert the energy of radiation at a lower level, which is insufficient to influence the chemical bonds. The efficiency of various additives to the polymer, stabilizing it against the action of ultraviolet radiation, can be estimated by various methods, which will be discussed in this chapter.
Tags: PEX, PEX plastics, UV radiation
