UV resistance is defined as a material's ability to resist ultraviolet (UV) light or sunlight. UV light will cause non-durable materials and surfaces to fade or discolor. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original EssayThe biological and chemical effects of UV light are greater than simple heating effects, and many practical applications of UV radiation arise from its interactions with organic molecules. The problem caused by UV rays is known as UV degradation. There are several ways to avoid UV degradation in plastic by using stabilizers, absorbents or blockers. There are numerous methods to reduce this degradation problem. Adding carbon black to the polymer is one such chemical inhibitor available for some plastics to improve UV resistance. The impact of ultraviolet radiation on human health has implications for the risks and benefits of sun exposure. Getting too much sun exposure can be harmful, but in moderation it is beneficial. The market offers several polymers that are inherently resistant to UV rays. Silicone paints and coatings can also be used to completely cover surfaces exposed to sunlight (UV radiation). Another important thing that we must consider in relation to UV resistance is the cladding material that we must choose for our building. In construction, cladding is used to provide a certain degree of thermal insulation and resistance to atmospheric agents and to improve the appearance of buildings. Your choice of siding has a significant effect on the environmental performance of your home. There are test methods used to predict the UV stability of a product over a number of years.1. What is UV? UV or ultraviolet light is electromagnetic radiation, which has a wavelength between 10 nm and 400 nm. It is shorter than that of visible light but longer than the sun's X-rays. UV radiation is present in sunlight and represents approximately 10% of the Sun's total light emission. "Ultraviolet" means "beyond violet" (from the Latin ultra, "beyond"), violet being the color of the highest frequencies. high levels of visible light. Ultraviolet has a higher frequency than violet light. UV radiation was discovered in 1801 when German physicist Johann Wilhelm Ritter observed that invisible rays just beyond the violet end of the visible spectrum darkened paper soaked in silver chloride more rapidly than violet light itself.2. Effects of UV light. As a result, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation arise from its interactions with organic molecules. Three benefits of UV exposure are vitamin D production, improved mood and increased energy. Ultraviolet light is responsible for the formation of bone-strengthening vitamin D in most terrestrial vertebrates, including humans. This vitamin helps regulate calcium metabolism, the creation of serotonin and melanin. Tanning, freckles and sunburn are familiar effects of overexposure, along with higher risk of skin cancer. Living things on land would be seriously harmed by the Sun's ultraviolet radiation if most of it were not filtered by the Earth's atmosphere.3. UV degradation. Many natural and synthetic polymers are attacked by ultraviolet radiation, and products using these materials can break down or disintegrate if they are not UV stable. TheThe problem is known as UV degradation and is a common problem in products exposed to sunlight. Continuous exposure is a more serious problem than intermittent exposure, as the attack depends on the extent and degree of exposure. Many pigments and dyes can also be affected.4. How to prevent UV degradation? UV attack from sunlight can be improved or prevented by adding anti-UV chemicals to the polymer when mixing the ingredients, for example before shaping the product by injection molding. UV stabilizers in plastics usually work by preferentially absorbing UV radiation and dissipating the energy as low-level heat. The chemicals used are similar to those in sunscreen products, which protect the skin from UV attacks. They are frequently used in plastics, including cosmetics and films. Different UV stabilizers are used depending on the substrate, expected functional life and sensitivity to UV degradation. UV stabilizers, such as benzophenones, work by absorbing UV radiation and preventing the formation of free radicals. Depending on the replacement, the UV absorption spectrum is changed to suit the application. Concentrations normally range from 0.05% to 2%, with some applications up to 5%. Often, glass can be a better alternative to polymers when it comes to UV degradation. Most commonly used types of glass are highly resistant to UV rays. Explosion-proof lamps for oil rigs, for example, can be made of polymer or glass. Here, UV rays and bad weather put a strain on the polymer, so much so that the material must be replaced frequently. The effects of UV degradation on materials requiring long life can be measured with accelerated exposure tests. With modern solar concentrator technologies, it is possible to simulate 63 years of natural exposure to UV radiation on a test device in just one year. UV radiation is divided into three different types as described in the table below along with their characteristic effect. DESCRIPTION WAVELENGTH RANGE ( nm) COMMON EFFECT UVA 320 - 400 SKIN TANNING UVB 280 - 320 SKIN BURNING UVC 100 - 280 GERMICIDAL 5. Material Resistance Tests Two of the accepted UV stability tests in the coated fabric industry include the AATCC 16-2004 Color Fastness to Light Test Method and the ASTM D4329-05 Standard Practice for Fluorescent UV Exposure of the plastic. These tests simulate weathering and realistically reproduce the physical damage caused by shortwave UV radiation by exposing materials to alternating cycles of UV light (using special fluorescent UV lamps) and moisture at high, controlled temperatures. In just a few days or weeks, the UV testing machine can reproduce damage that occurs naturally over months or years. Samples of the textile material to be tested are exposed to a UV light source under specific conditions. The color fastness to light of the sample is evaluated by comparing the color change of the exposed portion of the test sample to the original unexposed material. The color change can be measured with a spectrophotometer. The upholstery industry standard for UV resistance testing is at least 40 hours without any color change. High performance faux leather upholstery for hospitality, contract and healthcare applications can withstand more than 200 hours without any color change.6. Importance of UV Resistance An increasingly important performance value for coated fabrics is resistance to ultraviolet (UV) light. It is known that iPolyurethane and vinyl materials used for both interior and exterior applications are subject to photodegradation when exposed to ultraviolet light.7. UV Light Transmission Ultraviolet (UV) light transmission is traditionally considered negative for greenhouse growers due to its degrading effects - not only on painting materials - but also on components within a greenhouse, such as irrigation and electrical equipment. Some growers, however, welcome UV light because it contains the spectrum found in natural growing conditions. By allowing UV light into a greenhouse, you have the best of both worlds: a protected growing environment and the same light spectrum found outdoors. . Holubowsky says some green industry companies have used glazing materials that allow UV light transmission, including acrylic products specially designed to transmit UV rays to allow natural lighting for their breeding and testing grounds.8. Polymers with good UV resistance Plastic materials are often used for exterior applications such as architectural glazing, mass transit interiors, and marine dock fenders. Some plastics such as acrylic, Ultem®, PVDF and PTFE are inherently UV stable. However, most plastic materials exhibit a color change and loss of elongation when exposed to UV light. The weather resistance of some plastics can be improved by adding UV stabilizers or UV-resistant caps to protect the base polymer. Acetal Homopolymer, Copolymer (Polyozimethylene, POM) Unmodified acetal resin will degrade over time upon exposure to sunlight. The material may crack, become brittle and develop a chalky appearance. Pigmented and chemically modified formulations are available, including Delrin® 107 acetal and Delrin® 507. DuPont has developed 20 years of exposure data on these materials. Nylon (all types) Non-pigmented resins degrade with exposure to sunlight evidenced by discoloration and embrittlement. Formulations containing carbon black particles provide the best UV stability. Rigid polyurethane Thermoplastic polyurethane has good resistance characteristics to atmospheric agents. After exposure to UV rays a color change occurs, however there is minimal change in mechanical properties. Polycarbonate Unmodified polycarbonate resins (Hydex® 4301, Lexan®, Makrolon®) degrade with exposure to sunlight. Polycarbonate will yellow and become opaque after 1 year of exposure. UV resistant grades are available. PBT Polybutylene terephthalate (PBT) (also known as Hydex® 4101, Valox®, Celanex®, Ultraform®) is “inherently” resistant to UV rays. Supplier data indicates that degradation of mechanical properties is minimal after several years of exposure. Black pigmented resins have better property retention. PEIPoletherimide (Ultem®) is intrinsically resistant to ultraviolet radiation. After 1000 hours of exposure, no measurable change with tensile strength. ABSABS is not suitable for outdoor applications due to its poor UV resistance. Current UV stabilized grades refer only to color fastness and not to the maintenance of mechanical properties. Polysuphone Polysuphone (Udel®) will undergo some degradation following exposure to sunlight. To improve performance, black pigmented formulations are recommended.E = Excellent resistance to UV raysF = Fair resistance to UV raysU = Unacceptable resistance to UV rays9.Coating systems for external roofsThe coating is a.