UV resistance is defined as the ability of a material to resist ultraviolet (UV) light or sunlight. UV light will cause fading or discoloration of non-resistant materials and surfaces. Say no to plagiarism. Get a tailor-made essay on "Why violent video games should not be banned"? Get the original essay The biological and chemical effects of UV light are greater than simple heat effects, and many practical applications of UV radiation arise from its interactions with organic molecules. The problem caused by UV is known as UV degradation. There are several ways to prevent UV degradation of plastics by using stabilizers, absorbers or blockers. There are a number of methods to reduce this degradation problem. Adding carbon black to polymer is one of them as chemical inhibitors 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. exposure can be harmful, but moderation is beneficial. The market offers several polymers that are intrinsically UV resistant. Paint and silicone coatings can also be used to completely cover surfaces exposed to sunlight (UV radiation). Another important thing to consider When it comes to UV resistance, it is the covering material that we should choose for our building. In construction, cladding is used to provide a degree of thermal insulation and weather resistance, as well as to improve the appearance of buildings. Your choice of siding has a significant effect on the environmental performance of your home. There are testing methods used to predict the UV stability of a product over several years.1. What is UV? UV or ultraviolet light is electromagnetic radiation with a wavelength between 10 nm and 400 nm. It is shorter than that of visible light but longer than that of X-rays from the sun. UV radiation is present in sunlight and represents approximately 10% of the Sun's total light output. “Ultraviolet” means “beyond violet” (from the Latin ultra, “beyond”), violet being the color of the highest frequencies 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 quickly than violet light itself. even. Effects of UV light. Therefore, 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, mood improvement. , and an increase in energy. Ultraviolet light is responsible for the formation of vitamin D, which strengthens bones in most land vertebrates, including humans. This vitamin helps regulate calcium metabolism and create serotonin and melanin. Tanning, freckles and sunburns are familiar effects of overexposure, as well as higher risk of skin cancer. Living things on land would be seriously damaged by the Sun's ultraviolet radiation if most of it was not filtered by the atmosphereterrestrial.3. UV degradation. Many natural and synthetic polymers are attacked by ultraviolet rays, and products using these materials can crack or disintegrate if they are not UV stable. The 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, because the attack depends on the extent and degree of exposure. Many pigments and dyes may also be affected.4. How to prevent UV degradation? UV attack from sunlight can be mitigated or avoided by adding UV blocking chemicals to the polymer when mixing the ingredients, before shaping the product by injection molding for example. UV stabilizers in plastics generally act 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 damage. They are frequently used in plastics, including cosmetics and films. Different UV stabilizers are used depending on the substrate, expected lifespan and susceptibility to UV degradation. UV stabilizers, such as benzophenones, work by absorbing UV radiation and preventing the formation of free radicals. Depending on the substitution, the UV absorption spectrum is modified to match 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 very resistant to UV rays. Explosion-proof lamps for oil rigs, for example, can be made from polymer or glass. Here, UV radiation and bad weather damage the polymer so much that the material must be replaced frequently. The effects of UV degradation on materials that require long life can be measured through accelerated exposure testing. With modern solar concentrator technologies, it is possible to simulate 63 years of natural UV exposure on a test device in a single year. UV radiation is divided into three different types, as described in the table below, along with their characteristic effect. DESCRIPTION WAVELENGTH RANGE ( nm) EFFECT COMMUNUVA 320 - 400 SKIN TANNING UVB 280 - 320 SKIN BURNING UVC 100 - 280 GERMICIDAL5.Testing Material ResistanceTwo of the UV stability tests accepted in the coated fabric industry include the method Test Guide AATCC 16-2004 Color Fastness to Light and ASTM D4329-05 Practical for fluorescent UV exposure of plastics. These tests simulate weathering and realistically replicate the physical damage caused by shortwave UV radiation by exposing materials to alternating cycles of UV light (using special fluorescent UV lamps) and humidity at temperatures high and controlled. Within days or weeks, the UV testing machine can naturally reproduce the damage that occurs over months or years. Samples of the textile material to be tested are exposed to a UV light source under specified conditions. The color fastness to light of the specimen is assessed by comparing the color change of the exposed portion of the specimen to the original, unexposed material. The color change can be measured using a spectrophotometer. The upholstery industry standard for UV resistance testing is at least 40 hours without change incolor. High performance faux leather covering for hospitality, contract and healthcare applications can last over 200 hours without color change.6. Importance of UV Resistance An increasingly important performance value for coated fabrics is resistance to ultraviolet (UV) rays. Polyurethane and vinyl materials used for interior and exterior applications are known to be subject to photodegradation when exposed to ultraviolet light.7. UV Light Transmission Ultraviolet (UV) light transmission is traditionally considered negative for greenhouse producers due to its degrading effects - not only on glazing materials - but also on components of 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 get 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 specifically designed to transmit UV rays to allow natural lighting for their livestock plots and test.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 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 (polyozymethylene, 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 Acetal Delrin® 107 and Delrin® 507. DuPont has developed 20-year exposure data on these materials. Nylon (all types) Non-pigmented resins will degrade upon exposure to sunlight, as evidenced by discoloration and embrittlement. Formulations containing carbon black particles provide the best UV stability. Rigid PolyurethaneThermoplastic polyurethane has good aging characteristics. Upon exposure to UV rays, it undergoes a color change, but there is a minimal change in mechanical properties. PolycarbonateUnmodified polycarbonate resins (Hydex® 4301, Lexan®, Makrolon®) will degrade upon exposure to sunlight. Polycarbonate will yellow and become cloudy after 1 year of exposure. UV resistant grades are available.PBTPolybutylene terephthalate (PBT) (also known as Hydex® 4101, Valox®, Celanex®, Ultraform®) is “inherently” UV resistant. Supplier data indicates that there is little degradation of mechanical properties after several years of exposure. Black pigmented resins have better property retention. PEIPolyetherimide (Ultem®) is inherently resistant to ultraviolet rays. After 1000 hours. exposure, no measurable change with tensile strength. ABSABS is not suitable for applications.