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Comparison of UVA-340 Outdoors and UV aging

2021-11-18

The UVA-340 lamp is well simulated with the solar light of the wavelength of 360 nm, as the UVA-340 lamp can simulate most of the destruction The sunlight of the spectral zone of the polymer, so at least in theory it can expect it to obtain a reasonable correlation with the outdoor exposure results. Therefore, different polymeric materials samples were exposed to Florida, Arizona and Ohio. The same samples were tested in two irradiation and two humidity cycles in the laboratory to accelerate the aging test chamber, and then compared to artificially accelerated aging and nature exposure. In addition to the mildew, the material accelerated in laboratory with humidity cycles. Similar to the degradation mode of outdoor aging, in 15 materials of the test, 9 materials were accelerated in the manual aging test chamber due to increased irradiation. In addition, the study also confirmed that the acceleration factor and the material itself were greatly associated.

UVA-340, UV aging, accelerated aging, artificial aging, ASTM G53, ASTM G7, weather resistance test Introduction

The correlation between the laboratory accelerated aging and the natural aging test results have long been the focus of debates and disputes. Under normal circumstances, industry users want to get accelerated aging test results faster, but also hope to have good correlation between laboratory simulation and real outdoor exposure results. Unfortunately, these two goals seem to be reversed. Thisbecause the three main methods of accelerating aging results (ie, the temperature is higher than normal exposure, the spectral wavelength is less than natural light and the irradiance is higher than normal irradiance) will reduce this correlation, so the debate has not been reached Consistent.

But the industry seems to have reached some degree of consensus. If the light source used by the manual accelerated aging equipment can realize the distribution of solar spectral energy of the test material sensitive spectral zone, artificial aging usually gives outdoor exposure Close results. The filtered xenon lamp can well simulate most of the wavelength bands of the solar spectroscopy, especially ultraviolet rays that are visible and long-wavelength. The UVA-340 fluorescent ultraviolet tube is capable of highly analoging short-wave ultraviolet (lt; 365 nm) in the spectrum.

As shown in FIG. 1, the UVA-340 tube is well simulated of the solar light of the wavelength of 360 nm, as the UVA-340 lamp can simulate the sunlight of the spectral area of most polymers, so At least in theory, it can be expected to obtain a reasonable correlation with outdoor exposure results. In order to verify the theory, aging exposure procedures is developed, and the UVA-340 lamp tube can be used to compare the test results between outdoor aging and laboratory artificial aging.

15 different plastics and coatings are outdooted outdoor in three different places, laboratory in fluorescent ultraviolet and condensing devices Accelerated aging. Three different accelerated aging cycles, measurement and recording of gloss and color changes in outdoor natural aging and artificial accelerated aging.

Outdoor aging

It is well known that the factors that cause product degradation are often referred to as aging, which are very different from all over the world. In order to characterize Outdoor Aging in this study, 3 different outdoor places are selected: are the subtropical climate, desert climate, and northern industrial areas.

Select Florida Miami as the subtropical climate aging test site because the sun radiation intensity here is high, and the ultra-ultra-high-radiation intensity is high, the annual temperature is high, and the annual rainfall is high and humidity. Because these climatic conditions in Florida are often seen as worst, the state is often used as a benchmark site for outdoor aging test. Selecting Arizona Phoenix City as a desert climate aging test site is also because here utilitarian irradiation intensity is high and the annual temperature is high as a pole location. Choosing Ohio Clevelan as the northern industrial area aging test site is because here is located in the northern industrial area of the United States, with a typical hybrid industrial manufacturing environment. All outdoor aging is carried out according to the ASTM G7-non-metallic material environment exposure test standard specification. Test samples were mounted on a 1.6 mm (0.25 inches) exposure bracket, samples were 45 ° angles, facing south. Choosing 45 ° angle and facing south is because thisoften seen as a typical exposure angle, which is a test angle in many industries. For materials that do not have a specific tilt angle in actual use, 45 ° is most common.

The test material is the same as the material used in the last study, and the last study is to quantify high-radiation illumination to various common plastic and coating degradation. Speed effect. Most of these materials are commercially available products, and they may represent the generic types.

All laboratory artificial exposure

Sun is able to control and closed the loop feedback circuit QUV / SE UV aging test box equipment. Requirements for Standard Operations Specifications for Standards of Numerical ASTM G53 - Non - metallic Material Exposure Light and Water Test Equipment (Fluorescence UV - Condensed). UVA-340 lamps with a spectral peak of 343 nm, the cutoff is 295 nm. Select a single exposure temperature (50 ° C) to avoid any possible temperature affect interference. Laboratory aging exposure conditions are as follows:

Cycle 1: UVA-340 tube at 340 nm is 0.83 W / m2.4H ultraviolet light and 4H condensation cross-replacement, ultraviolet light and condensation cycle temperature It is 50 ° C.

The ultraviolet irradiation set in this cycle is the same as those in which the irradiance control is controlled, and the irradiance of the sun in 340 nm is substantially the same as the radiation of 340 nm in the summer.

Cycle 2: UVA-340 lamp tube at 340 nm is 1.35 W / m2.4H ultraviolet light and 4h condensation alternate, ultraviolet light and condensation cycle temperature It is 50 ° C. In addition to increasing the irradiance for determining whether the test can be accelerated without affecting the correlation, the other is the same as the cycle 1.

Cycle 3:

The irradiation at the UVA-340 tube at 340 nm is 1.35 W / m2. Only ultraviolet light (100% ultraviolet light, no moist, no dark cycle), the exposure temperature is 50 ° C.

UV Degradation Assessment:

Sample color and gloss were measured according to standard ASTM D2244 and standard D0523. These two standards are standard specifications and mirror gloss test methods for calculating color tolerance and color difference using instrumentation. Outdoor exposure samples were evaluated at 12 months and 24 months respectively. Depending on the speed of the test material and the degradation, the sample exposed in the G53 apparatus is tested at different time intervals.

PVC film: This material is a transparent unstable film that uses it The pressure-sensitive adhesive adheres to a white painted aluminum plate.

PVC film natural aging results (Figure 2):

This material varies small after 2 years of exposure of Ohio and Florida. In Arizona, this material aging was slightly yellow after 1 year, and it turned brown after 2 years. In Arizona, the first year is slower, the second year is accelerating.

Artificially accelerated aging results (Fig. 3):

No matter how high is low, QUV ultraviolet light accelerated in 4 h ultraviolet light / 4h condensation cycle After 2000h, the material changes very small. When the radiographic ultraviolet light is aging, the material begins to turn yellow after 1000 hours, and it turns brown after 2000 hours. Comparison: The QUV UV aging test chamber for ultraviolet light recycling is consistent with the exposure of Arizona. No changes have been observed for a long time in a long period of time, but the materials have occurred.The situation in rapid yellowing. Obviously, this material requires a certain amount of ultraviolet rays to excite the yellowing process. Once the ultraviolet energy is reached, the yellowing process will be very fast. This point occurs approximately 1200h at accelerated aging. When exposed to aging in Arizona, the time appeared approximately 1 year after aging. When Florida and Ohio exposure, the yellowing is not appeared when 4H ultraviolet light / 4h condensation cycle is aging. This may be due to the sufficient amount of ultraviolet irradiation required for the material that has not been required to excite the yellowing process.

Blue vinyl polymer film:

This material is a non-transparent blue glossy film, which is adhered to the aluminum plate with a pressure sensitive adhesive. Natural aging results (Figure 4):

The luster of this material has become almost dim in three different places outdoors. Although the luster of the three places has the same gloss, there is still a difference in the appearance of the sample. Among them, Ohio samples become black, Arizona samples are yellow, while Florida samples do not have other changes in addition to gloss.

Artificially accelerated aging results (Figure 5): The gloss of this material is dropped from 75 after each cycle of the QUV UV aging test chamber. To 55. Samples of ultraviolet light cycling were performed slightly yellow.

Comparison:

QUV UV aging test chamber exposed 2000 hours after 2000 h, the same gloss decreased with outdoor age. Thisthe slower speed in the 15 materials tested in this study. The yellowing phenomenon found in Arizona also appeared in the laboratory test (only the ultraviolet light cycle), but it is also a relatively slow acceleration speed.

Polystyrene plate: This material is a transparent plastic plate having a thickness of 2.8 mm. It is usually used as a reference material for monitoring ultraviolet radiation in an aging test machine.

Natural aging results (Figure 6): All three outdoor exposed phenomena occurred in a rapid and severe yellowing. All three places have almost the same speed.

Artificially accelerated age (Figure 7): The material appeared rapidly and severely yellowing during each cycle. The yellowing speed of the high-radiation illuminance ultraviolet light recycle is the fastest, followed by 4H high-radiation, ultraviolet light / 4h condensation cycle aging, and then 4H ordinary ultraviolet light / 4h condensation cycle aging. Only high-radiation illuminance ultraviolet light cycles also produce the most severe yellowing.

Comparison: The cycle containing condensing procedures is very energetic with all three outdoor exposure. The granulation of yellowing and outdoor age 2 years after aging 2000hCause the same. The cycle of ultraviolet light is carried out in the outdoor exposure to produce a more extreme yellow.

Green vinyl polymer film:

This material is a non-transparent green film that is adhered to the aluminum plate with a pressure sensitive adhesive.

Natural aging results (Fig. 8): This material has become a turquoise color after exposed to three years in three outdoor ages. This color change is a change in the blue direction, or the negative increment of B *. Aging rarely occurs when aging, but aging is very obvious for 2 years. Therefore, the change is mainly between the first and second years. In addition to Arizona and Ohio samples, due to some unknown reasons, there is almost the same change in the three places. The edges of the film also have a curl and is lifted from the aluminum plate.

Artificially accelerated aging results (Fig. 9): The material has a slight blue phenomenon after aging 2000 h with a condensation cycle. However, this phenomenon does not appear on the cycle of ultraviolet light.

Comparison: The same color change in the same color of the outdoor age was generated when the condensation process was circulated. Accelerated aging speeds inverted second in 15 materials studied. However, this material did not appear in the ultraviolet acceleration apparatus, the thin film edges similar to the outdoor aging were warped from the aluminum plate. Guess may be due to the surride of the sample. In order to simulate this phenomenon, the film edge should be exposed to the exposure area of the sample holder.

Epoxy resin: This material is a glossy, gray coating paint coated on a steel substrate.

Natural aging results (Figure 10):

All three outdoor exposure agents have a very rapid decline in gloss and powdering. The aging was detected after 1 year. Samples of the three test places also have rust phenomena. Florida samples are covered with rust, while Arizona and Ohio samples are partially rusty.

Artificially accelerated aging results (Fig. 11):

Materials in three accelerated aging cycles, rapidly decline in gloss. Compared with normal irradiance, the high-radiation recycle will cause half of the luster to completely lose half. The cycle containing the condensing procedure can produce powder, but only the cycle of ultraviolet light does not occur.

Comparison: The circulation of condensing procedures, the luster of the sample and the phenomenon of powdering are very energetic with outdoor exposure results. However, laboratory aging does not produce rust phenomena in outdoor aging. Ultraviolet accelerated aging equipment is used in pure cold, therefore may require a stronger corrosive liquid for corrosion resistance. It can be accomplished by using a circulating corrosion / aging program.

PolyurethaneCoatings: This material is a glossy, gray coating painted primer applied to the steel substrate.

Natural aging results (Figure 12):

This material has a phenomenon in which gloss is declining in all three outdoor agents. Among them, the rapid decline in gloss in Florida and Arizona samples. After 2 years of exposure, the test panels of the three aging scenes were completely disappeared. All 3 samples of aging scenes have some powdering. In addition, Florida's test panels have a rusty surface, while Ohio samples have a rustset, and Arizona samples do not have rust.

Artificially accelerated age (Figure 13):

The circulation containing the condensing procedure has a very rapid losing and powdering. A circulating sample for ultraviolet light will also drop, but the speed is much slow, and there is no powder.

Contrast: The decline in circulating gloss with condensing procedures is very enemied with outdoor exposure results. But the sample in the ultraviolet accelerated aging equipment did not appear in Florida samples.

Automotive coating: This material is an unknown auto-outer facade, which is blue, high gloss, sprayed on an aluminum plate.

Natural aging results (Figure 14): This material did not appear in three outdoor aging exposure, and the luster decreased.

Artificially accelerated age (Figure 15): This material did not change in three laboratory accelerated aging cycles. Gloss detection shows that there are several percentage of mild gloss to decline.

Comparison:

Because the laboratory aging and outdoor aging did not change significant changes, it was unable to compare.

Polyester coating:

Thisa coating coating with moderate luster, tan, sprayed aluminum.

Natural aging results (Figure 16): This material has a losing phenomenon in all three outdoor exposure. The luster of Arizona samples is the fastest, followed by Florida, then Ohio. Arizona and Florida samples were obvious in the exposure of 2 years, even though Ohio only decreased.

Artificially accelerated aging results (Figure 17):

This material has a losing phenomenon in all three laboratory accelerated aging cycles. The decrease in gloss of all three cycles is obvious, but the gloss of high-radiation is ultraviolet light 4H / condensation 4H cycle is the fastest and most serious.

Comparison: UV accelerated aging is very consistent with Florida and Arizona exposed results. Its aging 2000H sample appearance is similar to the appearance of Florida and Arizona sample aging. The results of laboratory also consistent with the results of Ohio exposure results, but manual aging speed is faster, because the gloss of the Ohio sample is slower.

Acrylic plastic sheet:

Thisa commercial transparent sheet having a thickness of 3.2 mm.

Natural aging results (Figure 18): This material did not appear in all three outdoor exposure. Delta B * Detects a very small amount of yellowing in the display material.

Artificially accelerated aging results (Fig. 19):

This material did not change in three accelerated aging cycles. Delta B * Detects a very small amount of yellowing in the display material.

Contrast: Laboratory accelerated aging with outdoor exposure results, UVA-340 lamp does not produce yellowing phenomenon with natural exposure.

Polycarbonate sheet: Thisa commercial transparent sheet having a thickness of 3.2 mm.

Natural aging results (Figure 20):

This material has a yellowing in all outdoor exposure. Among them, Florida and Arizona samples are faster than Ohio samples, but after 2 years, Ohio samples have rushed to Florida and Arizona samples.

Artificially accelerated aging results (Figure 21):

This material has a yellow phenomenon when all laboratory accelerates aging. However, the yellow variable speed between three test cycles is very large. The circulating yellow variable speed of high-radiation is the fastest, followed by 4H high-radiation, ultraviolet light / 4h condensation cycle, and then 4H normal irradiance ultraviolet light / 4h condensation cycle. Only high-radiation of ultraviolet light is also produced by the most serious yellow variation.

Contrast: Laboratory acceleration test containing condensation cycles and all three outdoor exposure results are consistent. The degree of yellowing after 2000 hours of laboratory is substantially the same as the outdoor exposure of 2 years. The cycle of ultraviolet light is carried out in the outdoor exposure to produce a more extreme yellow.

Polyethylene sheet: Thisa commercial ultra high molecular weight white sheet having a thickness of 3.2 mm.

Natural aging results (Figure 22):

This material did not appear in three outdoor exposure, Delta B * detection indicated that this material had very small amount of yellow.

Artificial accelerated aging results (Figure 23):

This material did not change in three laboratory accelerated aging cycles. Delta B * Test Indicates that the color color has a very small amount of change in the blue direction. Contrast:

Laboratory accelerated aging is quite anastomotive with outdoor exposure. Although the results of color detection instruments have some deviations, there is no difference between the laboratory accelerated aging and outdoor exposure results.

ABS sheet: Thisa commercial acrylonitrile-butadiene-styrene-styrene-styrene-styrene-styrene-styrene-free sheet having a thickness of 3.2 mm.

Natural aging results (Figure 24): This material has a yellowing in all outdoor exposure. The yellow-variety of Arizona samples is slightly faster than Florida and Ohio sample yellow. Moreover, Arizona samples have been larger than 2 years after 2 years.

Artificially accelerated age (Figure 25): This material has a yellowing in all laboratory accelerated aging cycles. Only ultraviolet photographic circulating materials produce the fastest and most serious yellow change.

Comparison:

Laboratory accelerated aging test containing condensation cycles and three outdoor exposure results are consistent. The degree of yellowing in the laboratory accelerated 2000h is roughly the same as the outdoor exposure for 2 years. The cycle of ultraviolet light is carried out in the outdoor exposure to produce a more extreme yellow.

CAB sheet: Butyl acetate butyrate is a commercially transparent sheet having a thickness of 3.2 mm.

Natural aging results (Figure 26): This material has a clear yellowing in all outdoor exposure. Among them, the yellowing speed of Florida and Arizona samples is faster than Ohio samples. However, after 2 years of exposure, the yellow-modified degree of Ohio sample was substantially the same as Florida and Arizona samples.

Artificially accelerated aging results (Figure 27): This material has a significant yellow phenomenon in each UVA-340 exposure cycle. However, only ultraviolet light recycle yellow variable speed is much faster, and the most serious yellow change is produced.

Contrast: UVA-340 exposure test is very consistent with the results of three outdoor exposure. There is no significant difference in yellowness of all exposed aging.

Polypropylene sheet:

This material is a commercial white sheet having a thickness of 4.7 mm.

Natural aging results (Figure 28): This material has a significant yellow phenomenon when the outdoor exposure is 1 year.Arizona samples were yelloweding in Florida and Ohio samples. But the plate is a bit different after exposure for 2 years. Ohio sample will continue to yellow, Florida samples make moldy and become very dark, Arizona sample exposed 2 years than exposed 1 year of yellowness. At all 3, the material is degraded to the surface that can be easily scheduted by the finger, wherein the samples of Ailisana have the most serious degradation.

Artificially accelerated age (Figure 29): All three laboratory accelerated aging materials began to turn yellow. A circulating material for ultraviolet light is turned into yellow throughout the accelerated aging of 2000H. In the 2 cycles of the condensation process, the aging aging is about 700 h, the material begins to become yellow, and it will continue in the remaining time of 2000H accelerated aging. The material also degrades the extent that the surface can be easily scratched by the finger, which occurs in all three cycles, but the high-intensity irradiation cycle aging is even more such.

Contrast: Accelerated aging with condensation cycles is very consistent with outdoor exposure results, except for Florida samples. The material appearance in UV accelerated aging equipment is the same as all outdoor exposure. Accelerated aging samples containing condensation cycles will also become yellow, and then change in reverse, yellowing is shallow, as Arizona appears.

Nylon sheet:

This material is a commercial, 6/6 unsatisfactory sheet (light brown) having a thickness of 4.7 mm. Natural aging results (Figure 30):

This material initial color is light brown, and the color brightened or yellow in Arizona and Ohio exposed. The Sample of Florida has hined, but later starts moldy, color is black. After two years of exposure, the materials of all three places will also degrade the extent that the surface can be easily broken by a finger.

Artificially accelerated aging (Fig. 31): The accelerated aging of 2 condensation cycles, the material becomes brighter (yellow shallow). The material degrades to the surface that can be easily broken by a finger. Conversely, only the accelerated aging of the ultraviolet light cycle, the material becomes yellow, the surface has not become easily removed by the finger.

Contrast: Accelerated aging with condensation cycles is very consistent with outdoor exposure results, except for Florida samples. The color of the laboratory accelerates aging samples is even more false, the surface degradation of the material is the same as the outdoor exposure. However, the accelerated aging results of ultraviolet light cycle are not very energetic and either outdoor exposure. This indicates that humidity is key parameters affecting this material, and must be considered when simulating natural aging manually accelerated aging.

Contrast:

UV accelerated aging equipment using UVA-340 lamps QUV to all 15 materials can produce degradation results with outdoor exposure . The only difference is the mold and rust phenomenon that the laboratory accelerates aging cannot be exposed to the sun. But in order to achieve the consistency of these two aging tests, the exposure cycle must be included in the condensing process. If the condensation cycle is not included, 5 of these 15 materials have different laboratory accelerated aging degradation modes and outdoor aging degradation modes. In addition, the other three materials have very serious degradation. Therefore, if there is no condensation cycle, only 7 of these materials are agreed with outdoor exposure. When the test cycle includes a condensing process, all 15 materials of the laboratory accelerated aging results can be well matched with outdoor exposure results. UVA-340 lamp does not generate any yellow variants that appear when the fluorescent UV-B lamp exposure is exposed.

Acceleration:

This study confirmed that acceleration factors were closely related to the material itself. As a very rough calculation method, 1000 hours of laboratory accelerated aging degradation is about 1 year outdoor exposure (9: 1 accelerated aging). However, the range can be 2: 1 to 35: 1. It is clear that there is no unique acceleration factor for this data.

High radiation illuminance can accelerate the test results of certain materials. The high-radiation illumination exposure of the 15 materials of the test produced faster test results than the normal irradiance exposure. In any case, high irradiance does not affect the correlation between laboratory aging and outdoor aging. There is no doubt that not all materials are true, but 15 materials in this study are true. It is proven that only an ultraviolet light cycle is a bad accelerated aging method. Although the ultraviolet radiation is 2 times that of humidity aging cycle test. There are only five materials in 15 materials to produce faster degradation results in a cycle of ultraviolet light. The strange thing is that there are 3 degradation speeds in 15 materials. Therefore, it is recommended that ultraviolet accelerated aging of almost all materials seems reasonable for condensation cycles.

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