What are the Light aging Tests

It is well known that millions of economic losses are caused by aging every year. Aging often causes changes in the physical properties of textiles, coatings, plastics and other organic substances, mainly manifested in discoloration, loss of light, loss of strength, cracking, peeling, pulverization and oxidation. We know that sunlight, especially short-wavelength ultraviolet light, high temperatures, rain, dew and moisture in the form of high humidity are the main factors responsible for the above damage.

The Purpose of Light Aging Test

(1) In order to comply with relevant quality and technical standards;

(2) Avoid losses caused by aging;

(3) To enhance the reputation of the product;

(4) Check the quality of the supplier's products;

(5) Improve the weather resistance of products;

(6) Significantly reduce material costs;

(7) Expand the variety of products;

(8) To facilitate access to new markets;

(9) Win the competition;

How to Perform Light Aging Test?

Outdoor natural aging test

The results of the outdoor aging test are one of the closest tests to natural aging. Depending on the conditions of use of the product, we can choose different locations for outdoor exposure testing, such as Q-PANEL in the United States in two iconic locations: Florida and Arizona Sunshine Field. Florida has a typical subtropical climate with high irradiation intensity, high temperature, and high humidity. The harsh climate is ideal for outdoor exposure testing, especially for moisture-sensitive materials such as coatings, building materials and plastics. Also, Florida is very good for mold resistance testing.

Arizona provides harsher exposure to products. Compared to Florida, high ultraviolet light, extremely high temperatures, large daily temperature fluctuations, and low humidity levels are the most typical desert climates. In Arizona, annual irradiance is 20% higher than in Florida; Maximum temperatures are usually 15 °C higher. For most materials, degradation in this harsh environment is much faster than in Florida. It has a significant influence on the color of coatings, the thermal aging and physical properties of plastics, the lightfastness of plastic coatings, and the tensile strength of textiles.

Because these two natural exposure sites exhibit more rapid degradation processes than milder climates, "Florida weather resistance" and "Arizona weather resistance" are often used as benchmarks for durability testing.

In daily life, sunlight exposure is a very common environmental phenomenon. During the long-term use of coatings and plastics, polymer materials such as coatings and plastics often appear discoloration, pulverization, blistering, cracks, and shedding during long-term use under sunlight, which seriously affects the mechanical properties and appearance of the product. Therefore, in the research and development of coatings, plastics, and some automotive interiors, which are often exposed to light, it is necessary to simulate natural use conditions, that is, to conduct photoaging tests to evaluate them to provide an evaluation basis. At the same time, in order to quickly evaluate the performance of materials, the method of artificially accelerated photoaging is often used in the photoaging test of new materials.

Laboratory accelerated aging test

Because the natural aging test takes several years to determine the aging result, it is a great test for your time, schedule, and funds. At the same time, due to the ever-changing climatic conditions in various places, the same tested material may get very different results. Large aging results, the repeatability and reproducibility of the experimental results are not very good. Therefore, people tend to use laboratory equipment to artificially accelerate aging, which not only shortens the test cycle, has good repeatability, and can be used for quality control and material stability testing. At the same time, this method has a wide range of applications because it is only used indoors. , can not be limited by natural conditions, only the influence of human factors can be considered, and the whole test process can be completed by the test box. Artificial accelerated aging can be roughly divided into three categories: carbon arc lamp simulation acceleration, ultraviolet light accelerated artificial aging, and xenon arc lamp accelerated aging. The carbon arc lamp simulated accelerated aging test chamber was the first to appear. Because of the shortcomings of high maintenance costs, inability to correct, and narrow simulated spectral range, there are not many people who rarely use it now.

Three Light Aging Test Methods

Light aging test methods mainly include:

carbon arc lamps,

fluorescent ultraviolet lamps,

xenon arc lamps,

carbon arc lamps

The ultraviolet carbon arc lamp device uses a suitable voltage between the upper and lower parts of the carbon rod in the instrument, and the current generates a larger energy generated by the arc, and can emit continuous spectrum ultraviolet light. The difference of the solar carbon arc lamp device is that the carbon rod contains a special metal element, so the spectral energy emitted is closer to sunlight. However, the short-wave ultraviolet rays of the solar carbon arc lamp are too strong, and there is no sunlight on the earth's surface, which does not match the real environment. Moreover, the difference between long-wave ultraviolet rays and visible light and sunlight is still large, so it is not widely used.

fluorescent ultraviolet lamps,

Fluorescent UV lamps can accelerate damage to many products. Because the light it produces exists on the Earth's surface and is radiant energy not found in natural sunlight, fluorescent installations can cause unnatural damage. Also, materials sensitive to longer wavelength UV energy may not change as much as they would when exposed to natural sunlight due to the absence of longer wavelength spectral energy. Fluorescent ultraviolet lamp equipment is a device that uses low-pressure mercury vapor arc discharge to excite fluorescent substances to produce ultraviolet light corrosion, which can generate continuous spectra in relatively narrow wavelength intervals. Fluorescent UV lamps are electrically similar to ordinary cold fluorescent lamps for lighting, but generate more ultraviolet light than visible or infrared light. Common fluorescent ultraviolet lamps include UVA-340, UVA-351, and UVB313. Among them, the light emitted by UVA-340 lamps is the closest to the ultraviolet part of natural light, which is more suitable for testing conditions that simulate actual lighting. The ultraviolet light emitted by the UVB-313 lamp tube is stronger than the ultraviolet light in natural light, so it is more suitable for comparative tests or destruction tests.

xenon arc lamps,

The xenon arc lamp device is considered to be the most able to simulate the full solar spectrum test device, because it can produce ultraviolet, visible and infrared light, and the spectral energy distribution of the gas arc lamp is closest to that of sunlight in the ultraviolet and visible band. Because of this, xenon arc irradiation is now the most widely used technique to simulate optical burn-in testing,

Xenon arc lamp device is a device filled with high purity xenon arc discharge lamp as the light source, the lamp tube is made of a transparent quartz glass tube, each end is sealed with a metal electrode, when the electrode is added to the appropriate high voltage and filtered by the filter plate will produce a spectrum closer to the sunlight.

The unfiltered xenon arc light in the xenon arc lamp device is not a good model of the natural exposure of the Earth's surface, and the spectrum of the sample is generally simulated by several optical filters. When using borosilicate glass internal and external filters (daylight filters), the spectral energy distribution emitted by the xenon arc lamp device is similar to the outdoor natural sunlight, and when the external filter is changed to sodium-calcium glass (window glass filters), it is close to the natural sunlight filtered by the glass window. When the inner filter is changed to quartz glass (extended UV filter), the spectrum has shorter shortwave UV rays that are not present in outdoor sunlight.

The three different types of lighting conditions each have their own advantages and disadvantages. The choice of which test method should be based on the characteristics of the product itself and the external environment during actual use. Carrying out artificial accelerated light aging test can have a more accurate and in-depth understanding of product performance and lifespan, and promptly eliminate products with poor quality or poor light resistance. In addition, when choosing different types of lighting conditions for testing, you must first understand the structure of the sample and the purpose of the test, such as whether you want to simulate the actual lighting conditions or do destructive lighting conditions, or want to do full-spectrum lighting The conditions still want to focus on simulating the ultraviolet light conditions, so that the correct photoaging conditions and testing equipment can be selected accordingly.

The Chambers Needed to Perform the Tests

1.UV Accelerated Weathering Test Chamber

In the 1970s, ultraviolet accelerated aging test chambers appeared. We know that ultraviolet rays in sunlight, especially peaks below 360 nm in the spectrum, are the main cause of material aging.LIB’s UV accelerated weathering test chamber emits ultraviolet spectrum through ultraviolet lamps to simulate the ultraviolet part of sunlight to accelerate the aging of materials. The peak wavelength of its fluorescent UVB lamp (UVB-313) is around 313 nm, and its energy is almost entirely concentrated between 280 and 360 nm. The wavelength range of the energy distribution is shorter than that of sunlight, which can speed up the experiment to the greatest extent. For UVA-340 lamps, the ray wavelengths are mainly concentrated between 295 and 360 nm, and the short-wave radiation of UVA-340 lamps is very similar to direct sunlight below 325 nm. According to different aging requirements for materials, customers can choose different UV lamps. In addition, the LIB’s UV accelerated weathering test chamber also has a high-precision photometric control system, which allows users to choose the desired illuminance level. With the help of the system, the light intensity can be controlled. Continuous monitoring, automatic and precise maintenance. When choosing a UVA-340 lamp with an intensity of 0.68 W/m2/nm and a wavelength of 340, it can match the intensity of sunlight at noon in summer. At the same time, LIB’s UV accelerated weathering test chamber can also simulate the influence of rain and dew, which can be achieved in two ways: condensation and water spray. Condensation is consistent with natural humidity. Through the accelerated test process by increasing the temperature, the condensation product produced is pure water-no water stains or impurities are produced on the sample. Spraying simulates mechanical erosion due to steady temperature fluctuations and rain wash-off.

International standards applicable to UV accelerated aging testing mainly include ISO 4892-1:1999 "Plastic Laboratory Light Source Exposure Test Method Part 1: General Rules"; ISO 4892-3:1994 "Plastic Laboratory Light Source Exposure Test Method Part 3: Fluorescent UV Lamp"; ASTM G-151 "Test Standard for Non-metallic Materials Laboratory Light Source Exposure Accelerated Test Device"; ASTM G-154 "Ultraviolet Fluorescent Light Source Exposure Test Method for Non-metallic Materials", etc.

2.Xenon Arc Accelerated Weathering Test Chamber

In the 1950s, the first xenon arc lamp simulated accelerated aging tester appeared in the world. Xenon arc lamps use the full sunlight spectrum as the light source, and the use of properly filtered xenon arc lamps is the best way to test the sensitivity of products to long-wave ultraviolet and visible light in direct sunlight or sunlight through glass. It can not only simulate the light resistance of indoor materials, but also simulate the climate environment. At present, the most widely used xenon lamp aging machine has two categories: rotating drum testing machine and testing machine with static sample placement. The rotating drum is designed so that a light tube is placed in the center of the container, surrounded by a rotating sample holder, which rotates around the light source. Such sample placement systems are often described as "rotating drums".

In the aging test chamber where the sample is statically placed, the tested sample is left still, and the aging is strictly controlled through various control methods, including xenon lamps that simulate the complete sunlight spectrum, a variety of filter systems and ISO 9000 Standard calibration, black panel temperature control system, test methods meeting ISO and ASTM requirements, three-dimensional sample holder and water spray function.

Due to the variety of xenon arc testing chambers that can be selected at present, most standardization organizations (including ISO and ASTM) tend to develop performance-based testing methods and methods. These methods define the test conditions (such as irradiation, spectrum, temperature, humidity, etc.) and acceptable performance ranges.

Contact LIB

Which Light Aging Test chambers do you need? LIB can provide you with:

the best Light Aging Test chamber,

the most professional solution,

the most desirable service

according to your testing requirements and standards.