Xenon-Arc Exposure of Plastics Designed for Indoor/Outdoor Applications by ASTM D4459, ASTM D2565, and ASTM G155 methods. As per the performance criteria of concern, the parameters compared are Haze, Transmission, Yellowness Index, Color Change, and/or physical properties such as Impact Strength.
Accelerated weathering simulates the harmful and hazardous effects of long-term outdoor exposure of materials and coatings. The test samples are exposed to the most aggressive weather conditions like rain, wind, sand and dust, icing, light, moisture, heat, and many more. A direct correlation between accelerated weathering duration and actual outdoor exposure time does not exist. Quality comparisons under the regulated conditions of accelerated weathering can be made with a recorded performance of materials and coatings that have been exposed to end-use for long periods of time.
A xenon arc light source is used in a Weather-Ometer to create a radiation spectrum that mimics natural sunlight. The light spectrum is modified by glass filters around the xenon arc to mimic the required end-use conditions. A humidifier and direct spray provide moisture, and heaters regulate the temperature. The radiation applied to the test samples is monitored and precisely regulated by microprocessors. Up to 60 test samples are placed in the Xenon Arc and exposed to various combinations of light, humidity, temperature, and water spray for a period of exposure. Depending on the intended end-use application, various cycles are specified by the relevant requirements.
To track and verify the equipment’s results, Polystyrene Lightfastness Standards are included among the test samples. These loops will be repeated over and over for thousands of hours, simulating even longer periods of time in the real world.
Specimens are normally, 69 mm × 145 mm in size. Smaller or slightly larger sizes may be accommodated, but actual parts are not readily accepted by this equipment.
Exposed samples can be compared to unexposed control samples thanks to accelerated weathering. Several exposure periods (such as 500, 1000, and 2000 hours) can often be compared. Such a comparison can include measurements of Haze, Transmission, Yellowness Index, Color Change, and/or physical properties such as Impact Strength, depending on the performance criteria of concern.