1、Designation: D4364 05D4364 13Standard Practice forPerforming Outdoor Accelerated Weathering Tests ofPlastics Using Concentrated Sunlight1This standard is issued under the fixed designation D4364; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers the use of Fresnel-reflecting concentrators that use the sun as a sourc
3、e of ultraviolet (UV) and longerwavelength radiation. Such devices are used in the outdoor accelerated exposure testing of plastics.1.2 This practice provides a procedure for performing outdoor accelerated exposure testing of plastics using a Fresnel-reflectoroutdoor accelerated weathering test mach
4、ine. The apparatus is described herein and in Practice G90 more completely.1.3 This practice is applicable to a range of plastic materials including, but not limited to, plastic films, sheets, laminates, andextruded and molded products in a variety of shapes and sizes, as specified in 8.2 and 8.3.1.
5、4 This practice describes test conditions that attempt to simulate plastics exposures in desert and subtropical climates.Specimen preparation, property testing procedures, and the evaluation of results are covered in existing test methods orspecifications for specific materials.1.5 The values stated
6、 in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and
7、 health practices and determine the applicability of regulatorylimitations prior to use. Specific precautionary statements are given in Section 7.NOTE 1This standard and ISO 877.2-1991, Method C, are technically equivalent.is equivalent to ISO 877-3: 2009.2. Referenced Documents2.1 ASTM Standards:2D
8、859 Test Method for Silica in WaterD883 Terminology Relating to PlasticsD1435 Practice for Outdoor Weathering of PlasticsD1600 Terminology for Abbreviated Terms Relating to PlasticsD1898 Practice for Sampling of Plastics (Withdrawn 1998)3D4141 Practice for Conducting Black Box and Solar Concentratin
9、g Exposures of CoatingsD4517 Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption SpectroscopyE772 Terminology of Solar Energy ConversionE824 Test Method for Transfer of Calibration From Reference to Field RadiometersG7 Practice for Atmospheric Environmental Exp
10、osure Testing of Nonmetallic MaterialsG24 Practice for Conducting Exposures to Daylight Filtered Through GlassG90 Practice for Performing Accelerated Outdoor Weathering of Nonmetallic Materials Using Concentrated Natural SunlightG113 Terminology Relating to Natural and Artificial Weathering Tests of
11、 Nonmetallic Materials2.2 ISO Standard:4ISO 877.2-1991,877-3: 2009 Method C, Methods of Exposure to Direct Weathering, to Weathering Using Glass-FilteredDaylight, and to Intensified Weathering Using Fresnel MirrorsPlasticsMethods of exposure to solar radiationPart 3:1 This practice is under the juri
12、sdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.50 on Durability of Plastics.Current edition approved Sept. 15, 2005July 15, 2013. Published October 2005August 2013. Originally approved in 1984. Last previous edition approved in 20022005as D4364 02.D43
13、64 05. DOI: 10.1520/D4364-05.10.1520/D4364-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last appr
14、oved version of this historical standard is referenced on www.astm.org.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM stan
15、dard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by AST
16、M is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Intensified weathering using concentrated solar radiation3. Terminology3.1 De
17、finitionsFor definitions of technical terms pertaining to plastics used in this practice, see Terminologies D883, D1600,E772, and G113 (for weathering terminology).4. Significance and Use4.1 This practice involves the concentration of sunlight by a system of plane mirrors, arranged to simulate a par
18、abolic troughfocused on an air-cooled target board on which the test specimens are mounted. Exposure cycles with and without water spray thatare commonly used for this method are described in Table 1. Other exposure cycles not listed in Table 1 can be used, uponconsensual agreement between intereste
19、d parties.4.1.1 Accelerated outdoor exposure tests performed using this practice in an absence of a programmed moisture cycle areintended to simulate conventional exposure testing on racks facing the equator in desert and arid regions.4.1.2 Accelerated outdoor exposure tests performed using this pra
20、ctice with a programmed moisture cycle shall possess thefeature of spraying high purity water on the specimens in a regular, periodic fashion that is intended to simulate the results ofconventional exposure testing on fixed racks facing the equator in subtropical, semi-humid, and temperate regions.
21、Water-spraycycles that are recommended by this practice are given in Table 1.4.2 The effectiveness of the Fresnel-reflector accelerated outdoor weathering test machines depends primarily on the amountand character of the UV in the direct-beam component of sunlight.NOTE 2Use of the apparatus in regio
22、ns of moderate- to high-diffuse irradiance will reduce the test machines effectiveness substantially for providingconcentrated UV in the target (specimen) area.4.3 Testing to specific levels (quantities) of solar ultraviolet radiant exposure is recommended. Elapsed time exposure-leveldeterminations
23、shall not be used for testing with this practice. Testing to specific levels of UV irradiation, whether to total UV orwithin selected wavebands, is an effective method for improving agreement between wintertime and summertime testing on theFresnel-reflector weathering-test machines. Other seasonal f
24、actors such as temperature and time of wetness can affect theweathering of test specimens significantly.4.4 The weathering machines described provide for specimen cooling that reduces thermal problems in most materials. It isrecommended that monthly temperature measurements be performed on heat-sens
25、itive plastics to record the typical monthly testspecimen temperatures.NOTE 3It is possible for heat-sensitive plastic materials and thick specimens that are self-insulating to exhibit thermal-induced degradation that isunrealistic compared to natural weathering. Clear, thin-film photodegradable pla
26、stics are not recommended for testing with this practice for this reason.4.5 Since the natural environment varies with respect to time, geography, and topography, it can be expected that the effects ofnatural exposure will vary accordingly. Furthermore, all materials are not affected equally by incr
27、eased irradiance and temperature.The quantitative correlation between exposures conducted in accordance with this practice and those conducted under specifiednatural exposure conditions will therefore vary with the type and composition of the material.4.6 While reference materials tested in accordan
28、ce with this practice and Practices G7 and D1435 are useful for providinginformation on the relationship between accelerated and real-time tests, the acceleration factor found for the reference materialcannot be used to extrapolate results of the accelerated test to predict lifetimes under natural e
29、xposure except for the specificmaterial for which the relationship has been established.5. Apparatus5.1 The testing apparatus shall be a Fresnel-reflecting device possessing ten flat mirrors that focus direct sunlight onto anair-cooled specimen area. A more complete description of the apparatus can
30、be found in Practice G90. See Fig. 1. (Single AxisTracking) and Fig. 2 (Dual Axis Tracking).TABLE 1 Fresnel-Reflector Test Machine Standard Spray CyclesCycle Daytime NighttimeSpray Duration Dry-Time Duration Cycles, h Spray Duration Dry-Time Duration Cycles, hWater is sprayed on the test specimens a
31、t:1 8 min 52 min 1 8 min 172 min 9:00 p.m.12:00 midnight3:00 a.m.2 no water spray used no water sprayused3A no water spray used 3 min 12 min 4 cycles per hour(from 7PM to 5 AM)A This is the cycle specified in Procedure C of Practice D4141.D4364 132NOTE 4The apparatus should be operated in dry, sunny
32、 climates receiving 3500 to 4000 h or more of sunshine per year and an average annual relativehumidity of approximately 30 % or less.5.2 Water Quality:5.2.1 The purity of water used for specimen spray is very important. Without proper treatment to remove cations, anions,organics, and particularly si
33、lica, exposed panels will develop spots or stains that do not occur in exterior exposures.5.2.2 Water used for specimen spray shall leave no objectionable deposits or stains on the exposed specimens. It is stronglyrecommended that the water contain below 1 ppm solids and below 0.2 ppm silica. Silica
34、 levels should be determined inaccordance with the procedures in Test Methods D859 or D4517. Prepackaged analysis kits are commercially available that arecapable of detecting silica levels of below 200 ppb. A combination of deionization and reverse-osmosis treatment can producewater with the desired
35、 purity effectively. The solids and silica levels must be reported if the spray water used is above 1 ppm solids.5.2.3 If specimens are found to have deposits or stains after exposure in the apparatus, the water purity must be checked todetermine if it meets the requirements above. On some occasions
36、, exposed specimens can be contaminated by deposits frombacteria that can grow in the purified water used for specimen spray. If bacterial contamination is detected, the entire system usedfor specimen spray must be flushed with chlorine and thoroughly rinsed before resuming exposures. Although it do
37、es not alwayscorrelate with silica content, it is recommended that resistivity of water used for specimen spray be continuously monitored andthat exposures be discontinued whenever the resistivity falls below 1 M.6. Reagents and Materials6.1 Water shall conform to the specifications presented in 5.2
38、.1-5.2.3.FIG. 1 Schematic of a Fresnel-Reflecting Concentrator-Accelerated Weathering Machine Single Axis TrackingD4364 1336.2 The mirrors used on Fresnel-reflector test machines shall be flat and have a specular UV reflectance of 65 % or greater at310 nm wavelength.7. Safety Precautions7.1 Suitable
39、 eye protection shall be required when working with Fresnel-reflector test machines to prevent UV and infrareddamage. Manipulation of the reflectors for daily maintenance, or for the purpose of specimen mounting, dismounting, andinspection, can reflect the concentrated sunlight on the face accidenta
40、lly.The use of sunglasses that absorb most of the UVradiationbelow 360-nm wavelength is essential; aluminized glasses will prevent accidental burning of the retina by infrared.7.2 Suitable clothing or sunscreen ointments having an SPF of 15 or higher, or both, should be used to cover exposed skin fo
41、rpersons working with the test machines described in this practice.7.3 The squirrel-cage blower shall be covered with a heavy-duty protective screen to prevent accidental injury and to keep looseclothing from the fan during startup, shutdown, maintenance, inspection, or specimen exchange.8. Test Spe
42、cimens8.1 It is strongly recommended that users of this accelerated outdoor exposure practice follow the statistical procedures forsampling presented in Practice D1898.FIG. 2 Schematic of Fresnel-Reflecting Concentrator Accelerated Weathering Machine Dual Axis TrackingD4364 1348.2 The target dimensi
43、ons presently used for most Fresnel-reflector accelerated weathering machines are 130 by 1400 mm. Thetarget dimensions shall dictate the test specimen dimensions.8.3 It is strongly recommended that the maximum specimen thickness used is 13 mm. The air cooling process and mechanismdictates that the t
44、hickness of test specimens be limited to 13 mm. The adequacy of cooling can be questionable for test specimensthicker than 13 mm.8.4 Test specimens smaller than the maximum size shall be arranged as shown in Practice G90.9. Procedures9.1 Mounting:9.1.1 Mount the test specimens in a suitable frame su
45、ch that a minimum of the test specimen is covered by the clamping fixtureused.NOTE 5A masked area or specimen overlapping should not be used in an attempt to estimate the effects of a dark exposure at the same temperaturesince a masked area or specimen overlapping is not unexposed and the temperatur
46、e may actually be higher than the unmasked areas.9.1.2 Mount the framed test specimens approximately 5 mm off the target board. Position the specimen such that adequateclearance is maintained between the air delivery slot and the frame.Adjust the machines air deflector to provide a clearance from6 t
47、o 13 mm between the exposed surface of the test specimen and the air deflector lip. Plastic test specimens with widely disparatethicknesses shall not be mounted on the same test machine in order to provide for uniform cooling.9.1.3 When mounting plastic specimens under glass to simulate the types of
48、 exposures under glass covered in Practice G24,ensure that the solar spectral transmittance (particularly in the UV region from 295 to 385-nm wavelength) of the glass used isessentially identical to that used in natural weathering with which it is being compared, or that its spectral transmittance i
49、s thatrequired for the application. Mount the glass covers, or plastic transparencies (if the application calls for a transparency other thanglass), such that they cover the entire specimen with respect to the reflected light from all of the mirrors. Mount the transparentcovers at a distance of 25 to 32 mm from the specimen surface. Common practice is to mount the transparent cover at a distanceof 25 mm from flat, plastic specimens, and to use a greater distance for non-flat specimens (see Fig. 23). This distance is closeenough to the specimen to block all reflec
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