MATERIALS | ACCELERATED TESTING
ISO are currently considering developing more appropriate standards. Despite some unknowns, suppliers of plastic compounds and parts need to begin to estimate the effect of UVC on the durabil- ity of their products. The Atlas UVCTest is a new device designed to test the durability of materials exposed to UV radiation from UVC-254 lamps (centered at 254nm radiation). These are designed to simulate the UVGI used by many sterilisation devices, says McGreer. Atlas scientists have also developed an Excel- based “UVC Test Duration Calculator” that calcu- lates the accumulated radiant exposure simulated by the equipment. Users can input variables, such as the level of radiant exposure per application and the number of expected applications, to determine appropriate times to expose materials in the test device. Exposed samples can then be measured to determine how much degradation has taken place.
Data acquisition Atlas also released a new web-based data acquisi- tion system in July 2021. The WXView II application remotely collects test parameter, control system and other data outputs in real time from any Atlas Ci4400 instrument connected to the user’s local area network. “The application allows users to access the information from their instrument from anywhere in the world, and the data is secure and encrypted,” says McGreer. “Data files from archived tests can be viewed, downloaded and imported into other applications for more detailed analysis and report generation. Instrument status and information on alarms, mainte- nance, and instrument configuration may also be displayed on the touchscreen user interface,” he adds. The current version resides on a company network but future versions may be Cloud-based. Launched by Q-Lab earlier this year, the QUV/ uvc accelerated weathering tester uses a UVC
Examples of various vinyl flooring samples before and after 24hrs exposure to UVC radiation in Q-Lab’s QUV/ uvc system
lamp with light concentrated at 254nm. The new QUV model has additional light baffles and safety features to prevent UVC light from exiting the device. The company has also added UVC testing capabilities using the new device at its Florida (US) and Saarbrücken (Germany) contract test laboratories. Bill Tobin, Senior Technical Marketing Specialist
at Q-Lab Corporation, described UVC testing in a presentation at the Compounding World Expo held in North America in November. He pointed out that the UVC-254nm lamp produces much higher irradiance at 254nm than xenon and fluorescent UV, so the test times to simulate UVC exposure will be much faster than standard weathering tests. For initial tests using the new device, Q-Lab researchers chose an irradiance of 6 mW/cm2
, a
35°C black panel (using active cooling to keep the panel close to room temperature), and ran continu- ously for 200 hours. It was expected that UVC light could cause more degradation because of the higher energy of UVC photons, and testing showed this to be the case. For example, a vinyl flooring material showed discoloration after just 24 hours of UVC testing.
Based on estimates of normal UVGI exposure,
daily UVGI cleaning accumulated over one year would correspond to about 17 hours of QUV UVC irradiance (at 6 mW/cm2
); 100 test hours would
represent about 5.9 years of daily UVGI exposure. Weekly UVGI cleaning for one year would be simulated in 2.4 hours of accelerated testing. More testing needs to be done to determine if higher irradiance testing can provide good correlation to the degradation caused in real world UVGI exposure.
Under pressure A high-pressure autoclave test (HPAT) is being studied for accelerating ageing of plastics at Germany’s SKZ. The test is particularly aimed at
Image: Q-Lab 60 COMPOUNDING WORLD | December 2021
www.compoundingworld.com
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