Artificial aging test

Artificial aging test refers to an artificial accelerated aging test method that simulates and strengthens the main factors in the atmospheric environment, and can obtain the results of similar conventional atmospheric exposure in a short period of time. This method simulates changes in various appearances or properties that occur during the irradiation of sunlight, temperature, humidity, and rain in the atmosphere.

(1) Preparation before test The sample should be adjusted according to the actual conditions used before the test. At the same time, the appearance gloss, color, etc. of the sample should be inspected and records should be made. Each group of samples should be prepared with an appropriate number of consistent samples ( Usually 4), one for use as a standard sample, and the rest for artificial weathering; all samples should be permanently marked in a suitable manner, if necessary, the edge of the sample is coated with a protective coating with high mechanical strength; In the preparation process, the surface of the paint film should be clean and free from dirt. You can use alcohol to clean it and wear disposable gloves for operation.

(2) Selection of light source The principle of light source selection is that the spectral characteristics of the artificial light source should be similar to the wavelengths that cause the material to be aged and destroyed, and it should be considered in conjunction with the purpose of the test and the use environment of the material. Studies have shown that radiation in the near-ultraviolet (300-400nm) wavelength range of sunlight is a major factor in the degradation of plastics. Generally, the intensity of ultraviolet radiation increases, and the aging rate of the material increases. Therefore, the closer to the sun's spectral line in the ultraviolet spectrum of the artificial light source, the better the simulation of the light source. Now three types of light sources are recommended internationally: xenon arc lamps, carbon arc lamps, and fluorescent UV lamps.

(3) Test temperature setting The test temperature setting shall be based on the maximum temperature of the environment in which the material is used. Normally, it is selected at about 50°C. The selection of the temperature of the xenon lamp black board should be based on the highest temperature of the material surface in the use environment. Generally, it is selected at (63±3)°C. The sample irradiation temperature should not be too high, especially for temperature-sensitive materials. Because the temperature is too high, the test results may not be the result of aging due to light, but the result of thermal effects. Therefore, when the xenon lamp ages, care must be taken to prevent the sample from overheating. For open carbon arc lamps, the air flow must be strengthened to avoid excessive temperature rise.

(4) Relative humidity setting The effect of relative humidity on material aging varies according to the type of material. The relative humidity should be set based on the annual average relative humidity of the environment in which the material is used. Normally, it is selected between 50% and 70%.

(5) Selection of Rainfall or Dewfall Cycle The choice of rainfall cycle is based on rainfall data from natural climates. The international rainfall time/no rainfall time is more than 18min/102min or 12min/48min, 3min/17min, and 5min/25min. However, the presence of water in the form of condensation may have a greater impact on accelerating exposure tests, so exposures with cycles of light and dark often require condensation time.

(6) Irradiation Selecting different kinds of plastics is selective for the absorption of the spectrum, that is, it has a particularly sensitive spectral region. Excessively high irradiance does not necessarily accelerate aging degradation, but may cause unexpected results. Therefore, the choice of irradiance should be appropriate.