Black panel temperature

An industrial standard method has been developed to test the lightfastness of polymers in accelerated test equipment [103]. The apparatus consists of a quartz-xenon tube with a special optical filter between the light source and the specimen to produce light that resembles window glass-filtered daylight [104], Samples are mounted at a specific distance from the arc and are supported on a frame which revolves around the arc 1 to 5 times per minute for uniform exposure. A blower unit in the base provides a flow of air which makes it possible to maintain a black panel temperature of 45°C, measured by a black panel thermometer which is positioned at level with the samples. A black panel unit consists of a bimetallic thermometer mounted on a steel frame. Both faces of the frame plate and also the stem of the thermometer are coated with a heat-resistant glossy black enamel. The relative humidity level in the exposure cabinet is closely controlled. 

Accelerated exposure equipment may also be used to test for weatherfastness in plastic materials [106], The natural destructive agents inherent in weather are approximated by filtering the radiation emitted by the xenon arc lamp and by spraying the sample with water under standardized conditions [106], Test programs are designed to relate to actual outdoor exposure to rain and humidity. In a standard program, a 3 minute wet cycle typically alternates with a 17 minute dry period. Weatherfastness tests are carried out and evaluated like lightfastness tests the black panel temperature and other parameters are the same in both procedures. 

The temperature of exposed samples is dependent on both the air temperature in the cabinet and the absorbance of direct radiation. Temperature is usually measured with a black panel thermometer, which gives the surface temperature of a perfectly absorbing material. White panel thermometers are also commonly used which measure the other extreme. The actual temperature reached by a test piece depends on the material and its colour. It will also depend on the air temperature and velocity so that both the air and black panel temperatures should be controlled. ISO 11403-3 [23] defines three sets of conditions in air with the black standard temperature at 65 °C (ISO 4892-2 Method A [27]), behind glass at the same temperature (ISO 4892-2 Method B [27]), and behind glass at 100 °C. 

The black panel temperature is measured with a thermocouple mounted on a flat black painted panel which is placed on the sample rack of the Weather-Ometer. As such, the temperature registered is meant to indicate a maximum temperature of the specimens under the same irradiation. 

Light Exposures. Silk fabric samples, 0.25 m x 0.17 m, were mounted in Atlas Electric Devices aluminum sample holders according to AATCC Test Method 16E-1982 (7). An Atlas Ci-35 Weather-Ometer xenon-arc was used on continuous light cycle. Exposures were conducted at an irradiance of 0.35 W/m2 measured at 340 nm and the irradiance was monitored and controlled automatically. Borosilicate inner and outer filters were used to simulate the solar spectrum. The relative humidity was maintained at 65% and the black panel temperature was 50°C. The actual fabric temperature during the irradiation was measured, using small thermocouples threaded into the fabric, and was found to be 35 C. Control samples for these tests were kept in the dark at 35°C and 65% RH for the same time period as the illuminated samples. 

Calculated from L,a,b values on a Hunter color difference meter (average of six readings on each sample) exposure in Weatherometer is listed in kilojoules per square meter (ambient dry bulb temperature, 85°F 3° wet bulb temperature, 70°F 4°, black panel temperature 100°F % relative humidity, 50 8%). Each 110 kJ/m2 corresponds to about 20 h exposure to noon sunlight conditions. 

Exposure of Bleached Pulp. Bleached pulp, based on 50% hardwood and 50% softwood kraft, jordaned to a Canadian standard freeness of 300-350 mL, was kindly supplied by Andrew Chase of the University of Maine. Unaged handsheets made from this pulp contained 85% a-cellulose (3) and 5% hot-1%-alkali-soluble matter (4). In the experiment illustrated in Figure 1, sheets were exposed in the Atlas 6500-W xenon-arc Fade-ometer equipped with Pyrex-glass filters the air temperature was 31 °C, and the relative humidity was 27% the black-panel temperature was 65 °C. Halfway through the reported period of... 

The fluorescent lamps were mounted 3 % in. above the samples in a room maintained at 50% rh and 21.1 °C (70 °F). Under these conditions the temperature of the handsheets reached 24 °C. In the 6500-W Fade-ometer, the air temperature was 31 °C, the relative humidity was about 27%, and the black-panel temperature was 65 °C. 

A 6000W xenon arc Atlas Weather-Ometer (] ) equipped with Corning No. 77 +0 horosilicate inner and outer filters was used as a laboratory light source because its emission spectrum is similar to that of sunlight, as illustrated in Fig. 1. The Weather-Ometer was operated with the lamp on continuously and the exposure chamber was maintained at a black panel temperature of ll+5 5°F and a relative humidity of 30 5. ... 

Ca-stearate (HALS-III, without AO-II). Test specimens compression-molded plates (2.0 mm thick). Weathering test sunshine carbon arc lamp weather meter (WEL-SUN-HC, Suga Test Instruments Co., Ltd.). Black panel temperature 63 3 C, without water spray. Failure criterion time to 507, loss of original elongation (half life time = H.L.T.). IF = H.L.T. with stabilizer/H.L.T. without stabilizer. (b) Test specimens compression-molded sheets (0.5 mm thick). Aging test forced air circulation oven at 150 C. 

Samples were exposed in a Weather-Ometer Model 65-WR (Atlas Electric Device Company) which uses a filtered-xenon source of UV radiation with automatic regulation for constant irradiance, 50% relative humidity, 60°C black panel temperature, and 18 minutes of water spray every two hours. 

The UV test exposure procedure corresponded to the cycle A [4] and provided an 8-hour UV exposure test with uninsulated black panel temperature control at 60 3°C. 

FIGURE 17.14 Yellowness index after 1600 h exposure in a Xenon Weather-Ometer (black panel temperature 63 3°C, without water spray) of HALS (LMW-HALS-1), UVA (UVA-BZT-6), and combinations (for combination total 0.3 wt%) [124]. 

Artificial weathering of plasticized PVC 1 mm (40 mil) thick. Plasticizer 50 phr OOP. Stabilizer systems Curve 1, no stabilizer Curve 2, ESO 3 phr, Ba/Cd/Zn/organic phosphite 2.25 phr Curve 3, same as for Curve 2 plus 1 phr of 2-hydroxy-4-raethoxybenzophenone UV absorber. Weathering Carbon Arc Weather-Ometer, black panel temperature 145 °F (63 °C), water spray 18 min every 2 h (52). 

Figure 1.46 Fading of commercial WPG boards in terms of lightness (L in the Hunter Lab color scale) shift after 1000 h of accelerated weathering (vertical axis) in Q Sun-3000 weathering chamber at 0.35 W/m at 340 nm, 102 18 min (UV light UV light -I- water spray) cycle, 63°C black panel temperature. AL values vary from 0.4 to 35 units/1000 h, that is in almost 100 times, for the boards available on the market. Since some boards can be outdated compared to current manufacturing, they are not named but numbered.

It is rather difficult, if possible at all, to quantitatively translate the fading in the weathering box to the real world. However, some very approximate comparisons can be made. Depending on the material color, one day in the weathering box under standard conditions (340 nm, 0.35 W/m, 102 18 cycle, 63°C black panel temperature) often corresponds to 9 + 4 days of natural weathering in the U.S. Midwest and New England. This figure is often called the acceleration factor. In Arizona and Florida, the acceleration factor is about 40% of the above, that is, around 3.5. 

Two GeoDeck hollow boards with the OIT of 3 min were kept in the weathering box for 8640 h (360 days) and 9140 h (381 days) at standard conditions (0.35 W/m at 340 nm, 102 18 min cycle, 63°C black panel temperature). Samples were taken from different parts of the boards, and results are shown in Table 15.33. 

TABLE 16.2 Acceleration factors for some polymers, exposed in Atlas CiSOOO Xenon-arc weatherometer according to ASTM G26 (102 min UV 18 min UV + water spray 340 nm, 0.35 W/m, black panel temperature of 63°C) and on a weathering rack in Milwaukee, WI, oriented to face south at an inclination of 45°... 

Weathering was conducted in Q-Sun 3000 weathering chamber according to ASTM D 2565 (340 nm, 0.35 W/m, 102 18 cycle, 63°C black panel temperature). Data by the author. 

Light only for 102 min, and light and water spray for 18 min. Same irradiance and black panel temperature as in Cycle No. 1 Cycle No. 3... 

Compared to ASTM D 2565, which lists five test cycles commonly used for xenon-arc exposure testing of plastics, ASTM G 155 describes 12 tests. However, the mostly used Cycle 1 of ASTM D 2565 (0.35 W/m at 340 nm, 102 min (UV light) 18 min (UV light + water spray, 63°C black panel temperature) is identical to Cycle 1 of ASTM G 155. 

Bonds with plastics, 142 Calcium carbonate in, 112, 141 Cellulose in, 112 Chemical composition, 112 Cost of, 112 Granules, 141 Ingredients, 141 Kaolin clay in, 112 Mold shrinkage, effect on, 142 Oil absorption, 141 Porosity, 141 Shape of particles, 142 Speciflc gravity, 142 Tensile modulus, effect on, 142, 143 Thermal expansion-contraction coefficient, 142 Biodegradable plastics, 79 Biodegradable wood-plastic composites, 91 Bioresistance, 42 Biotite, 146 Black Algae, 426 Black mold, 29, 31, 424, 429 Black panel temperature, 41, 132 Black panel thermometer, 612 Black panel, 41, 132 Bleached cellulose, 11, 14, 180 Cost, 14... 

The black panel temperature is measured with a thermocouple mounted on a flat black painted panel which is placed on the sample rack of tire Weatlier-Ometer. As such, the temperature registered is meant to indicate a maximum temperature of the specimens under tire same iiTadiation. Kockett, D., Factors of weathering. Presentation given at tire Atlas School of Natural and Accelerated Weathering (ASNAW) course, Miami, FL, 27-30 April, 1999, Atlas Electric Devices company, Chicago, IL, 1999. 

Weathering Procedures. Samples (7 x 12 cm) of untreated and formladehyde-treated wools were exposed to simulated sunlight weathering in an Atlas Weather-ometer, Model C135W equipped with a filtered xenon arc. The samples were irradiated continuously for 168 hours total with 18 minute water spray following every 102 minutes of Irradiation throughout the cycle. The fabric surface received 0.67 w/m irradiation at a black panel temperature of 63°C and 45% RH during the irradiation. 

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