UV aging belongs to sunlight radiation aging.

UV is the abbreviation of Ultraviolet (ultraviolet). It is usually used to evaluate the aging speed of products under ultraviolet light. Sunlight radiation aging is the main aging damage suffered by materials used outdoors. For materials used indoors, it is also It will be subject to a certain degree of aging caused by sunlight radiation or ultraviolet rays from artificial light sources (such as ultraviolet lamps, ultraviolet bands in fluorescent lamps, etc.). UV radiation includes the visible and ultraviolet portions of the solar spectrum. Ultraviolet light is divided into A rays, B rays and C rays (referred to as UVA, UVB and UVC), with wavelength ranges of 400-315nm, 315-280nm and 280-190nm respectively. According to UV aging related standards, UV (ultraviolet) cannot simulate full spectrum sunlight. Its principle is that for durable materials exposed to the outdoors, the short-band wavelength of ultraviolet rays of 300 to 400nm is the main cause of aging damage. In the short-wavelength region of ultraviolet light, from 365nm to the lowest wavelength band of sunlight, UV fluorescent lamps simulate sunlight well.

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UV aging test modes

The UV aging test can set three aging modes: light, condensation and spray.

1

The light stage simulates the daytime light length in the natural environment (usually between 0.35W/㎡～1.35W/㎡, the solar light intensity at noon in summer is about 0.55W/㎡) and test temperature (50℃～85℃), In order to simulate various usage environments of products and meet the testing requirements of different regions and industries.

2

The condensation stage simulates the phenomenon of fogging on the sample surface at night. During the condensation stage, the fluorescent UV lamp is turned off (dark state), only the test temperature (40~60℃) is controlled, and the sample surface humidity is 95~100% RH.

3

The spray stage simulates the process of rain by continuously spraying water on the sample surface. Since artificial ultraviolet accelerated aging test conditions are much harsher than those in the natural environment, aging damage that takes several years to occur in the natural environment can be simulated and reproduced in a few days or weeks. According to different spectral distribution, fluorescent ultraviolet lamps can be divided into UVA and UVB lamps. UVA lamps emit light energy below 300nm, which is less than 2% of the total output light energy, while UVB lamps emit light energy below 300nm. Greater than 10% of the total output light energy.

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Introduction to UV aging lamps

UVA-340: The main purpose is to simulate the short and medium wavelength range in the ultraviolet part of sunlight. It is generally used for photoaging tests of outdoor products.

UVA-351: The main purpose is to simulate the short and medium wavelength range in the ultraviolet part of sunlight filtered by window glass. It is generally used for indoor products.

UVB-313: They emit considerable amounts of radiation below 300nm, which is the nominal cutoff wavelength for solar radiation. This will cause some aging phenomena that do not occur outdoors. It is not recommended to use this lamp to simulate sunlight. This test is widely used primarily for accelerated durability testing of materials as a qualitative comparison of two or more materials.

The irradiation intensity of the lamp UVA-340 is as follows (reference):

0.69w/m^2@340nm is equivalent to the sunshine at noon in summer, getting fast results;

1.38w/m^2@340nm is equivalent to the maximum value of the sun, getting fast results;

0.35w/m^2@340nm is equivalent to March/September sunlight, suitable for ordinary testing or low UV light intensity testing.

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What are the common reference standards for UV aging?

GB/T 16422.3 Plastics - Laboratory light source exposure test methods - Part 3: Fluorescent ultraviolet lamps

ISO 4892-3 Plastics - Laboratory light source exposure methods - Part 3: Fluorescent ultraviolet lamps

ASTM 154 Standard Practice for Operating Fluorescent Ultraviolet Lamp Apparatus for Exposing Non-Metallic Materials