uvc effect on plastic

The total absorption is, therefore, an indicator of the potential for photodegradation in materials, while reflectivity can indicate protective effects. New York: Illumination Engineering Society of North America. Res Chem Intermed 28(7–8):857–870. The chain of molecules will begin to break down, causing both physical and chemical changes. USA: General Electric. High quality pure plastics are relatively resistant to UV but impurities and residual solvents in low-grade plastics are mainly responsible for their quick photodegradation. Feller RL. Yellowing of polymers from ultraviolet exposure tends to be concentrated on the immediate surface. Washington, DC: Ameri- can Chemical Society, pp. I also have a lifelong love for costuming. IESNA. Bolton J, Stefan M. 2002. UV Light and its Effect on Plastics Ultraviolet (UV) light is probably the most damaging environment for plastics. The technique involves pouring the water into a clear glass or plastic bottle, and leaving it out in the sun for six hours. Yellowing of polymers from ultraviolet exposure tends to be concentrated on the immediate surface. If plastic has been affected by ultraviolet rays, you may notice:a a chalky appearance the component surface becoming brittle a colour change on the surface of the material Rubbers in general such as motor belts and conduits used in the HVAC industry have proven to stand germicidal UV very well over the last 20 years of cumulated field experience. Since UV transmissivity tends to be very low for most materials, even at millimeter thicknesses, most of the photodegradation will occur on the immediate surface of a material, to a depth of typically less than 0.01 to 0.1 millimeter. While UVB radiation is widely recognized for its harmful effects on human skin and links to skin cancer, each of the UV bands (UVA, UVB and UVC) create different risks for humans. The three basic wavelengths: o UV-C - includes the germicidal wavelength of 253.7nm and is used for air and water disinfection. This indicates that the crystallinity of PS increases after UV irradiation, and the crystallinity of PS after UV sea water aging is the highest, followed by UV pure water aging, and finally UV air aging. The absorption of UV by itself, is not necessarily an indicator that UV damage may occur, since it is the photochemistry which determines material effects. The ability of UV-C light to penetrate materials will depend on the chemical composition of the materials. The samples were 1 mm thick and unstabilised (Mw ~60,350 ; Mn ~32,300). Surface yellowing tends to block UV and protects the inner plastic. Associated with this there would be some limiting distance, a film thickness or penetration depth, to which UV would penetrate. Germicidal Lamps and Applications. Lighting Handbook: Reference & Application IESNA HB-9-2000. Topics covered during this session include an introduction to UV degradation and an explanation of the failure mechanism characteristic of UV radiation/plastic interaction. Quantum yields as low as 0.0001 (10,000 photons per molecule) have been reported for most plastics. The absorption of UV by itself, is not necessarily an indicator that UV damage may occur, since it is the photochemistry which determines material effects. Much of the effect of sunlight on materials has been attributed to the UV component (IESNA 2000), UV can fade some wall paints, wallpapers, and drapery fabrics (GE 1950). The molecular makeup of certain materials can become damaged if those materials are not resistant to UV rays. Much of the effect of sunlight on materials has been attributed to the UV component (IESNA 2000), UV can fade some wall paints, wallpapers, and drapery fabrics (GE 1950). The visible and IR parts of the spectrum only contribute a little to aging. Jeff is a graduate of Carroll College and the Milwaukee School of Engineering. To limit the effects of UV on PVC pipe, an inhibitive additive is included in the material formulation. Ozone inhalation can be irritating to the airway. Accelerated Aging: Photochemical and Thermal Aspects. Most acrylic plastics will allow light of wavelength greater than 375 nm to pass through the material, but they will not allow UV-C wavelengths (100–290 nm) to pass through.

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