1、Designation: D4674 02a (Reapproved 2010)Standard Practice forAccelerated Testing for Color Stability of Plastics Exposedto Indoor Office Environments1This standard is issued under the fixed designation D4674; the number immediately following the designation indicates the year oforiginal adoption or,
2、 in the case 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. Scope1.1 This practice covers the basic principles and operatingprocedures for using fluo
3、rescent light to determine colorstability of plastics when materials are exposed in typical officeenvironments where fluorescent overhead lighting andwindow-filtered daylight are used for illumination and wheretemperature and humidity conditions are in accordance withAmerican Society of Heating, Ref
4、rigerating, and Air-conditioning Engineers (ASHRAE) recommendations forworkers comfort.1.2 This practice describes four methods where specimensare exposed to fluorescent light under controlled environmentalconditions. Two of the methods use an exposure device thatprovides for mixing of fluorescent l
5、amps and two of themethods use devices that comply with Practice G154.NOTE 1Method I uses cool white fluorescent lamps and window glassfiltered fluorescent UVB lamps and is the same method described inprevious versions of this standard.1.3 Specimen preparation and evaluation of the results arecovere
6、d in ASTM methods or specifications for specificmaterials. General guidance is given in Practice G151. Morespecific information about methods for determining the changein properties after exposure and reporting these results isdescribed in Practice D5870.1.4 The values stated in SI units are to be r
7、egarded as thestandard.1.5 Unless otherwise specified, all dimensions are nominal.1.6 This practice may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, is any, associated with itsuse. It is the responsibility of the user o
8、f this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Section 7.NOTE 2There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D172
9、9 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque MaterialsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD3980 Practice for Interlaboratory Testing of Paint andRelated Materials3D5870
10、Practice for Calculating Property Retention Index ofPlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG113 Terminology Relating to Natural andArtificial Weath-ering Tests of Nonmetallic MaterialsG141 Guide for Addressing Variability in Exposure T
11、estingof Nonmetallic MaterialsG147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering TestsG151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices that Use Laboratory Light SourcesG154 Practice for Operating Fluorescent Light
12、Apparatusfor UV Exposure of Nonmetallic MaterialsG169 Guide for Application of Basic Statistical Methods toWeathering Tests3. Terminology3.1 DefinitionsThe definitions given in TerminologyG113 are applicable to this practice.4. Summary of Practice4.1 This practice provides for the exposure of specim
13、ens tofluorescent light under controlled environmental conditions.Radiant energy is provided by one of the following fluorescentlight sources: (1) VHO cool-white fluorescent lamps and glassfiltered fluorescent UV lamps, (2) VHO cool-white fluorescent1This practice is under the jurisdiction ofASTM Co
14、mmittee D20 on Plastics andis the direct responsibility of Subcommittee D20.50 on Durability of Plastics.Current edition approved Oct. 1, 2010. Published March 2011. Originallyapproved in 1987. Last previous edition approved in 2002 as D4674 - 02a. DOI:10.1520/D4674-02AR10.2For referenced ASTM stand
15、ards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
16、hohocken, PA 19428-2959, United States.lamps alone, (3) standard output cool white fluorescent lampsalone, or (4) UVA-351 fluorescent UVA lamps.4.1.1 Method I is intended to simulate the conditions in anoffice environment plus a portion of solar UV radiationtransmitted by window glass. Methods II an
17、d III are intendedto simulate only the indoor lighting component of a typicaloffice environment. Method IV is intended to simulate only theeffects of a portion of solar UV radiation transmitted throughwindow glass.NOTE 3A comparison of the four listed methods has not beenperformed, and as such, resu
18、lts obtained from each method cannot beconsidered as equivalent.NOTE 4For more information on the use of fluorescent UV lamps tosimulate solar UV radiation behind window glass, refer to Annex A1 ofPractice G154.4.1.2 Do not compare Comparison of results obtained fromspecimens exposed using the metho
19、ds described should not bemade unless correlation has been established between themethods being compared for the materials being tested.4.2 Color change is determined periodically throughout thecourse of the exposure by comparison of the exposed speci-mens to unexposed specimens, using either visual
20、 or instru-mental procedures.5. Significance and Use5.1 Tests conducted in accordance with this practice areintended to induce property changes associated with useexposure to light and heat in typical office environments. Theseexposures are not intended to simulate the deterioration causedby localiz
21、ed phenomena such as handling, dirt contamination,etc.NOTE 5Caution: Caution: Refer to practice G151 for full cautionaryguidance applicable to all laboratory weathering devices. Additionalinformation on sources of variability and on strategies for addressingvariability by design and data analysis of
22、 laboratory accelerated exposuretests is found in Guide G141.5.2 Variation in results may be expected are possible be-tween the different methods described in this practice. Forexample, differences in spectral distribution of the lamps usedand variations in the irradiance for a single type of lamp c
23、ancause significant differences in test results. Therefore, any noreference to the use of this practice should be made unlessaccompanied by a report prepared in accordance with Section12 that describes needs to include a reference to the methodused.5.3 Reproducibility of test results between laborat
24、ories hasbeen shown to be good when the stability of materials isevaluated in terms of performance ranking compared to othermaterials or to a control. Therefore, exposure of a similarmaterial of known performance (a control) at the same time asthe test materials is strongly recommended. It is recomm
25、endedthat at least three replicates of each material be exposed toallow for statistical evaluation of results.6. Apparatus6.1 Test ChamberUnless otherwise specified, the testchamber shall comply with the requirements of Practice G151.6.1.1 The test chamber used for Methods I and II shall bedesigned
26、so that simultaneous operation of VHO cool whiteand glass filtered UV fluorescent lamps is possible, and shall beequipped with a radiometer complying with the requirementsof Practice G151 and calibrated from 250 to 400 nm. AnnexAnnex A1 contains more information about the design of theapparatus used
27、 for Methods I and II.6.1.2 The test chamber used for Methods III and IV shallconform to the requirements of Practice G154.6.2 The spectral distribution of the UVB-313, UVA-340,and UVA-351 shall comply with the requirements of practiceG154. The spectral power distribution of the cool white lampsused
28、 shall comply with the requirements given inAnnexAnnexA2.6.3 Window glassUnless otherwise specified the windowglass shall be good grade clear, flat, drawn “single strength”sheet glass free of bubbles or other imperfections and between2.0 and 2.5 mm in thickness. The glass shall be preaged in thedevi
29、ce for at least 24 hours prior to use.6.4 For Methods I and II, place the apparatus in an envi-ronment that meets ASHRAE recommendations of 20 to25.5C and 40 to 50 % relative humidity. For Methods III andIV follow the requirements of Practice G154 for the area inwhich the instruments are used.6.5 In
30、strument CalibrationTo ensure standardization andaccuracy, the instruments associated with the exposure appa-ratus (for example, timers, thermometers, UV sensors, andradiometers) require periodic calibration to ensure repeatabilityof test results. Whenever possible, calibration should needs tobe tra
31、ceable to national or international standards. Unlessotherwise specified, calibration schedule and procedure shallbe in accordance with manufacturers instructions.7. Hazards7.1 Never look directly at the operating lamps unlesswearing UV protective eyewear. The apparatus specified inSection 6 shall b
32、e constructed so that the operator will not beexposed to hazardous levels of UV radiation.7.2 Discard or recycle lamps in accordance with any rel-evant local ordinances when they are no longer suitable for thetests described.8. Test Specimens8.1 The recommended specimen size is a rectangular flatpie
33、ce 50 by 80 by 4 mm (minimum thickness). This size isadequate for visual or instrumental evaluation. Other specimendimensions may be used by mutual agreement among theparties concerned but exposed surfaces need to be coplanar formost consistent results.9. Test Conditions9.1 Conduct exposures in acco
34、rdance with one of thefollowing exposure methods.9.1.1 Method I:9.1.1.1 Use apparatus conforming to the requirements de-scribed in Annex Annex A1.NOTE 6For Method I, the contribution of fluorescent UV lampradiation to the total UV actinic exposure is adjusted by changing thepercentage of time the sp
35、ecimens are exposed to the various lamp types.9.1.1.2 This method provides for exposure of specimens toradiant energy from an array of very high output (VHO) coolD4674 02a (2010)2white fluorescent lamps plus intermittent radiant energy fromwindow glass filtered fluorescent UV lamps. The total UVradi
36、ant exposure from both sources is calculated by determin-ing the total UV irradiance from each type of lamp separatelyand calculating the product of the total UV irradiance andexposure time in Watt-hours/m2(W-h/m2).9.1.1.3 Place test specimens in the exposure area, leaving atleast a 25 mm empty bord
37、er around the exposure area.9.1.1.4 Run the device with both the cool white and fluo-rescent UV lamps on for at least 20 minutes, then turn off thefluorescent UV lamps and record the UV irradiance with onlythe cool white lamps operating (CWE in W/m2, 250-400 nm).Calculate the exposure time required
38、for the desired CWEradiant exposure as follows:CWt5CWHCWE(1)where:CWt= exposure time for cool white lamps,CWH= desired UV radiant exposure for cool white lampsalone, andCWE= UV irradiance measured with only with the coolwhite lamps operating.9.1.1.5 Run the device with only the fluorescent UV lampso
39、n and record the UV irradiance (UVE in W/m2, 250-400 nm).The UV actinic exposure from the filtered fluorescent UVlamps is set at 12 % of the UV actinic exposure for the coolwhite lamps. Calculate the total operating time for the fluores-cent UV lamps as follows:UVt50.12 3 CWHUVE(2)where:UVt= exposur
40、e time for fluorescent UV lamps,CWH= desired UV radiant exposure for cool white lampsalone, andUVE= UV irradiance measured with only with the fluo-rescent UV lamps operating.NOTE 7Although an office environment sees some UV exposure dueto sunlight through window glass, most photodegradation originat
41、es fromfluorescent lighting. The 12 % is an estimate of a representative officeenvironment.9.1.1.6 Calculate the fraction of time per hour for which thefluorescent UV lamps are turned off (UVOFF) as follows:UVOFF5CWt UVtUVt(3)(1) Replace the cool white lamps if UVOFFis greater thanor equal to one.9.
42、1.1.7 Program the device so that the cool white lampsoperate continuously and the fluorescent UV lamps are turnedon once per hour for the fraction of time calculated in section9.1.1.6. Continue the exposure for the total time calculated insection 9.1.1.4.9.1.1.8 Reposition the specimens at time inte
43、rvals equal to25 6 5 % of the total time calculated in section 9.1.1.4. Movespecimens just to the right of the center line of the exposurearea to the position farthest to the right in the exposure area andmove remaining specimens one position to the left. Movespecimens just to the left of the center
44、 line of the exposure tothe position farthest to the left in the exposure area and moveremaining specimens in this half one position to the right.9.1.1.9 Maintain chamber air temperature between 30 and40C during the exposure. If the air temperature exceeds 40C,the device must be shut off and the cau
45、se for the hightemperature corrected before exposures can continue.9.1.1.10 Conduct exposures for a total time agreed upon byall interested parties. Periodically remove test and controlspecimens for color measurement and relevant physical prop-erty tests.9.1.2 Method II:9.1.2.1 Use apparatus conform
46、ing to the requirements ofAnnex A, but without the fluorescent UV lamps.9.1.2.2 Place test specimens in the exposure area, leaving atleast a 25 mm empty border around the exposure area.9.1.2.3 Operate the device for at least 20 minutes thenrecord the UV irradiance (CWUV,inW/m2, 250-400 nm).Calculate
47、 the exposure time necessary for the desired coolwhite UV irradiance exposure in accordance with section9.1.1.4.9.1.2.4 Reposition the specimens during the exposure asdescribed in section 9.1.1.8.9.1.2.5 Maintain chamber air temperature between 30 and40C during the exposure. If the air temperature e
48、xceeds 40C,the device must be shut off and the cause for the hightemperature corrected before exposures can continue.9.1.2.6 Conduct exposures for a total time agreed upon byall interested parties. Periodically remove test and controlspecimens for color measurement and relevant physical prop-erty te
49、sts.9.1.3 Method III:9.1.3.1 Use apparatus conforming to the requirements ofPractice G154 and equipped with F40T12 cool white lamps.Place specimens in the devices, and fill all spaces not used bytest specimens with blank metal panels. Operate the devicewith lamps on continuously and with the black panel tempera-ture controlled at 50 6 3C.9.1.3.2 Specimen RepositioningPeriodic repositioning ofthe specimens during exposure is not necessary if the irradi-ance at the positions farthest from the center of the specimenarea is at least 90 % of that measured at the center
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