Standard Practice for Outdoor Weathering of Plastics

ASTM D 1435 Standard Practice for Outdoor Weathering of Plastics  

This standard considers the stability of plastics when they are exposed outdoors. The relative durability of plastics in outdoor use can be very different depending on the location of the exposure because of the differences in UV radiation, wetness, temperature, pollutants (acid rains, for example), and many other factors. Hence, exposure in several locations with different climates that represent a broad range of anticipated service conditions are recommended by this ASTM. Still, because of year-to-year climatological variations, resnlts of exposure in 1 year cannot be used to predict the absolute rate at which a material degrades. Therefore, several years of repeated exposure to get an average test result for a given location is recommended. 

According to the standard, unless otherwise specified, exposure racks should face the equator. The standard considers rack position at different latitudes, and the respective rack adjustments at certain periods of the year, and indicates that in most nondesert areas maximum annual UV exposure is provided by exposure at an angle of the latitude angle minus 10°. Besides, the standard considers at-latitude racks, 45° racks, 90° racks, horizontal racks (instead, 5° south exposure is recommended, to provide moisture runoff), and other angle racks. Materials and types of construction of test racks are also considered, as well as instruments for measuring solar radiation, ambient temperature and relative humidity, and their calibration procedures. 

The procedure recommends to measure and express total solar irradiance and total UV irradiance in MJ/m. As an example, it lists typical average (based on several years of measurements) UV radiant exposure for 12 months to be 308 MJ/m in subtropical climate at 5° exposure, and 333 MJ/m in desert climate at latitude exposure, both between 295 and 385 nm. 

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ASTM D 1435-85 Standard Practice for Outdoor Weathering of Plastics, 7 pp, (DOD Adopted) (FSC 9330) (MR) (Comm D-20)... 

Standard practice for outdoor weathering of plastics. ASTM D1435-05, 1985... 

ASTM D4364 Standard Practice for Conducting Accelerated Outdoor Weathering of Plastic Materials Using Concentrated Natural Sunlight ... 

ASTM D 4364 [209] Standard Practice for Performing Outdoor Accelerated Weathering Tests of Plastics Using Concentrated Sunlight... 

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