ACCELERATED TESTING | MATERIALS
glass filter and associated hardware – into a single, factory-sealed unit.
Advanced equipment that enables real-time
virtual monitoring of material properties while accelerated field testing is in progress is becoming increasingly popular, according to Atlas, as it provides a viable alternative to on-site visits, so saving time and travel expense. The company’s offering in this sector is VIEW (Virtual Inspection and Evaluation of Weathering), a remote service that first went on the market last autumn. Using VIEW, clients can remotely interact with technicians and experts while observing the effects of weathering on their specimens in real time. The next VIEW generation is WXView II, a web-based application that allows users to securely access their instrument test data from anywhere in the world. This method of data collection allows researchers to identify critical points of degrada- tion at key junctures and to better understand the progression of ageing mechanisms. The EYE Super UV Tester uses a proprietary high-output UV lamp to generate ultraviolet light and is among the latest introductions from Applied Optix. Its UV-irradiation intensity is 30 or more times greater than that of sunlight and convention- al weatherometers and, to achieve better solar correlation, the company says UV radiation below 295nm (UVC) is removed from the light source using a custom filter. Removing this radiation, which in natural sunlight does not reach earth, is said to result in an acceleration in deterioration that more closely resembles true outdoor exposure. The versatile tester can not only be used for plastics and polymers, but also for testing automo- tive materials, in building and construction, paint and coatings, and composite applications. As a screening tool, it is claimed to be able to generate five years of UV exposure in ten days, offering the opportunity to save money and considerably speed up the time to market for new products.
UVC exposure While UVC radiation may not be a component of natural sunlight, there are areas where plastics are exposed and potentially damaged by it. UK-based specialist polymer additives developer Radical Materials uses accelerated testing techniques and says UVC radiation testing now plays a key role in its business. UVC radiation has been used for many years to disinfect water supplies, pharmaceutical products, and general surfaces — the method is called Ultraviolet Germicidal Irradiation (UVGI). In recent times, and especially since COVID, there has been
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a dramatic increase in the use of this technology in industries such as transportation, retail, food processing and healthcare, where it is used to kill bacteria and viruses. “Whilst UVA and UVB radiation will reach the
earth’s surface as components of sunlight along with infrared and visible light, UVC never does as it is filtered naturally by the ozone layer, “ says Chris Vince, Technical Director at the company. “Many materials used are therefore not designed to withstand UVC, which is higher in energy than either UVA or UVB and potentially more damaging. UVC exposure can lead to significant degradation if the material is not designed for it, and the speed and extent of this degradation is still largely unexplored. UVGI doses received in-service can be extremely unpredictable and their application and subsequent material testing is currently poorly standardised.” Standard accelerated weathering tests focus on
UVA and UVB and tend to filter out the higher energy UVC element. Therefore, a conventional weathering test will tell a manufacturer or user very little about the effect of UVC on a particular material, and it can be a huge challenge to deter- mine whether the material is fit-for-purpose based solely upon its degradation over repeated UVC exposure cycles. Due to the increasing use of UVGI and its largely undocumented effect on material performance, new dedicated UVC test machines have been developed. Radical says these machines are not designed to administer UVGI, but rather to simulate and accelerate the UVC dosage of repeated UVGI cycles and subsequently test the effects on defined material parameters and properties. A typical method of utilising such a machine would be to develop a simulation based upon the UVC cycles the material is expected to be exposed to while in service. For example, if it is assumed that
September 2023 | COMPOUNDING WORLD 47
Above: UVC testing of samples in progress at Radical Materials
IMAGE: RADICAL MATERIALS
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