Four types of problems often appear in the aging test of xenon lamps First, the selection of artificial accelerated aging test conditions : This problem can be understood as the aging factor that should be simulated. During the use of polymer materials, many factors in the climatic environment may have an effect on the aging of polymer materials. If the main factors causing aging are known in advance, the test method can be selected in a targeted manner. We can determine the test method from the aspects of transportation, storage, use environment and aging mechanism of the material. For example, a hard polyvinyl chloride profile is made of polyvinyl chloride as a raw material, and is added with additives such as stabilizers and pigments, and is mainly used for outdoor use. Considering the aging mechanism of polyvinyl chloride, PVC is easily decomposed by heat; considering the use environment; oxygen, ultraviolet light, heat and moisture in the air cause the aging of the profile. Therefore, the national standard GB/T8814-2004 "unplasticized polyvinyl chloride ( PVC-U ) profiles for doors and windows ", not only specifies the photo- oxidation aging test method, using GB/T16422.2 "plastic laboratory light source exposure test" method II: xenon arc lamp "4000h or 6000h of aging, ultraviolet and visible simulated outdoor, temperature, humidity, rainfall and other factors, but also provides thermal aging items: the heated state, placing 30min 150 ℃, visual Observe the presence of bubbles, cracks, pitting or separation to investigate the heat resistance of the profile. Another example is China's competitive products in the international market: foreign trade exports shoes. During use, the ultraviolet rays in the sun are the main cause of discoloration and fading of the shoes. Therefore, it is necessary to use a UV light box to test the yellowing resistance. The commonly used footwear yellowing test chamber uses a 30W UV lamp, the sample is 20cm away from the light source , and the color change is observed after 3 hours of irradiation . At the same time, in the transportation process, the harsh environment of the hot and humid inside the container may cause discoloration, spots and even deterioration of the upper, the sole and the glue. Thus, prior to shipment, it is necessary to consider for heat aging test, the container simulated heat, high humidity environment, at 70 ℃, 95% relative humidity, 48h after the appearance of experimental observation, the color change. Second, the choice of artificial accelerated aging light source : The laboratory light source exposure test is a commonly used artificial accelerated aging test method because it can simultaneously simulate the light, oxygen, heat and rainfall in the atmosphere visible in a test chamber. Among these simulation factors, The light source is the most important. Experience has shown that the wavelengths that cause the polymer material to break in the sun are mainly concentrated in ultraviolet light and some visible light. The artificial light sources currently used strive to make the energy spectrum distribution curve in this wavelength range close to the solar spectrum. The simulation and acceleration magnification are the main basis for selecting artificial light sources. After about a century of development, the laboratory light source has a variety of light sources such as closed carbon arc lamps, sunlight-type carbon arc lamps, fluorescent ultraviolet lamps, xenon arc lamps, and high-pressure mercury lamps. The technical committees related to polymer materials in the International Organization for Standardization ( ISO ) mainly recommend the use of sunlight-type carbon arc lamps, fluorescent ultraviolet lamps, and xenon arc lamps. 1 , xenon arc lamp It is currently believed that the spectral energy distribution of a xenon arc lamp in a known artificial light source is most similar to the ultraviolet and visible light portions of sunlight. By selecting the appropriate filter, most of the short-wave radiation present in the surface sunlight can be filtered out. The xenon lamp has a strong radiation in the near-infrared region of 1000 nm to 1200 nm , which generates a large amount of heat. Therefore, you must choose the appropriate cooling device to take away this part of the energy. At present, there are two cooling methods for the xenon lamp aging test device on the market: water-cooled and air-cooled. In general, the cooling effect of the water-cooled xenon lamp device is better than that of the air-cooled type, and the structure is also complicated and the price is relatively expensive. Since the ultraviolet light energy of the xenon lamp is less than that of the other two light sources, it is the lowest in terms of the acceleration magnification. 2.2 fluorescent UV lamp Theoretically, short-wave energy from 300 nm to 400 nm is the main cause of aging. If you increase this part of the energy, you can achieve the effect of rapid test. The spectral distribution of fluorescent UV lamps is mainly concentrated in the ultraviolet light, so In order to achieve a higher acceleration rate. However, fluorescent UV lamps not only increase the UV energy in natural daylight, but also the radiant energy that is not found in natural daylight when measured on the Earth's surface, and this part of the energy causes unnatural damage. Further fluorescent light source in addition to a very narrow spectral lines of mercury, no energy greater than 375nm, so that the energy of longer wavelength UV sensitive material may change as exposure to sunlight does not occur in nature. These inherent defects can lead to unreliable results. Therefore, the fluorescent ultraviolet lamp is inferior in simulation. However, due to its high rate of acceleration, rapid screening of specific materials can be achieved by selecting the appropriate type of lamp. 2 , sunlight type carbon arc lamp Sunlight-type carbon arc lamps are currently used less in China, but they are widely used in Japan. Most JIS standards use sunlight-type carbon arc lamps. Many of China's auto companies that are joint ventures with Japan still recommend the use of such light sources. The spectral energy distribution of the sunlight-type carbon arc lamp is also closer to that of sunlight, but it is concentrated at 370 nm - 390 nm , and the simulation is inferior to that of the xenon lamp. The acceleration ratio is between the xenon lamp and the ultraviolet lamp. Third, the test time is determined : 1. Refer to the relevant product standard regulations Relevant product standards already makes provision for aging test of time, we just need to find the relevant standard, the time to implement the provisions of the press in the face on the line. This is stipulated in many national standards and industry standards. Table 1 lists some of the common product standards provisions of the aging time. 3.2 Based on known correlations Studies have shown that the color stability of ABS is evaluated by the change of color and yellowing index , and the artificial accelerated aging has a good correlation with natural atmospheric exposure, and the acceleration rate is about 7 . If you want to know the color change of an ABS material after one year of outdoor use, use the same test conditions, you can refer to the acceleration rate to determine the accelerated aging time 365x24/7=1251h . For a long time, a lot of researches have been carried out on related sexual issues at home and abroad, and many conversion relationships have been obtained. However, due to the diversity of polymer materials and the different aging test equipment and methods, the differences in climate at different times and regions have led to a complicated conversion relationship. Therefore, when selecting the conversion relationship, it is necessary to pay attention to the specific materials, aging equipment, test conditions, performance evaluation indicators and other factors of the correlation. 3 , control the amount of artificial accelerated aging radiation is equivalent to the total amount of natural exposure radiation For some products that have no corresponding standard regulations and no reference correlation, the radiation intensity of the actual use environment can be considered, and the total amount of artificial accelerated aging radiation is controlled to be equivalent to the total amount of natural exposure radiation. The following example shows how to control the total amount of radiation accelerated by artificial acceleration: A plastic product is used in the Beijing area, and it is expected that the total amount of artificially accelerated aging radiation will be equivalent to one year of outdoor exposure. Step: As the product is a plastic article, and for outdoor use, opt GB / T16422.2-1996 "Test methods of exposure to laboratory light sources Plastics second part: Xenon arc lamp" in the A method. The test conditions are: irradiation intensity 0.50W/m2 (340n m), black panel temperature 6 5 ℃, the temperature of the housing 4 0 ℃, relative humidity of 50% water time / no water spray time 18min / 102min, continuous light; Step two: shows the total amount of radiation a year in Beijing from Table 2, as 5609MJ / m2, based on comparative international norms artificial light source and nature of the spectral distribution of solar radiation CIENo85-1989 (see Table 3, GB / T16422.1-1996 "Plastics Laboratory Light Source Exposure Test Method Part I: Xenon Arc Lamp" is quoted ) ; the ultraviolet region and the visible region ( 300n m - 800nm ) account for 62.2% , or 3489MJ/m2 . The third step: According to GB/T16422.2-1996 , when the 340nm irradiation intensity is 0.50W/m2 , the irradiation intensity of the infrared region and the visible region ( 300nm to 800nm ) is 550W/m2 ; the irradiation time can be calculated as 3489X106/550=6.344X106s , which is 1762h . According to this calculation method, the acceleration magnification is about 5 . Since natural aging is not a superposition of simple irradiance, only when it is determined that sunlight is causing the material. Fourth, the selection of performance evaluation indicators : The selection of performance evaluation indicators is mainly considered from the aspects of the use of materials and the characteristics of the materials themselves. 4.1 Determine evaluation indicators based on material use For the same materials, the evaluation indicators may be chosen differently depending on their uses. For example, the same coating material, if it is used for decoration, it is necessary to consider the change in the appearance of the key. In GB / T1766-1995 "Paints and varnish coating aging rating" in details the gloss, color change, chalking, gold pan, and other changes in appearance rating method. For some functional coatings, such as anti-corrosion coatings, a certain degree of color and appearance change are acceptable. At this time, when selecting the evaluation index, the cracking resistance and the degree of chalking are mainly considered. The same is polyvinyl chloride ( PV C ) . If it is used to make the upper, it must consider its yellowing resistance. If it is used for rain downpipes, the requirements for appearance change are not high, and the physical and mechanical properties of the material change, such as The change in tensile strength is the main indicator. 4.2 Determine the evaluation index according to the characteristics of the material itself For the same material, the decline in performance during the aging process is not constant. In other words, some properties are sensitive to the environment and fall the fastest, which is the main factor causing material damage. These sensitive properties should be selected when selecting evaluation indicators. Studies have shown that for most engineering plastics, the impact strength is the most significant and the most obvious decline in natural aging test. Therefore, in the aging test of engineering plastics, priority should be given to selecting the drop in impact strength as an evaluation index. Impact strength is also quite sensitive to the aging of polypropylene [4] , which is the main indicator for assessing aging performance. For polyethylene materials, the drop in elongation at break is the most obvious and is a preferred indicator of evaluation. For polyvinyl chloride, tensile strength and impact strength are reduced relatively quickly, and one of them should be selected according to the actual situation. In GB GB / T8814-2004 "doors, windows made of unplasticized polyvinyl chloride (PVC-U) profile", select the impact strength retention after aging rate of ≥ 60% as determined eligible index; in light industry standard QB / T2480-2000 hard PVC for construction (PVC-U) Rainwater pipes and fittings, the select aging retention of tensile strength ≥ 80% as acceptable determination index. Ningbo Kebao Test Equipment Co., Ltd. is a professional production enterprise. The company mainly produces: programmable constant temperature and humidity test chamber, programmable high and low temperature test chamber, thermal shock test chamber, large walk-in constant temperature and humidity chamber, precision high temperature aging. Test chamber, salt spray test chamber, ultraviolet accelerated aging test machine, xenon weathering test chamber, various IP grade rain test chambers, simulated transport vibration test bench, drop test machine and other test equipment are welcome. 3 Blade Ceiling Fan,40 Inch 3 Blade Ceiling Fan,3 Blade Ceiling Fan Without Lamp,3 Balde Dc Ceiling Fan Guangdong Shunde Liangci Electric CO.,LTD , https://www.marckeez.com