1、Designation: D 4674 02aStandard Practice forAccelerated Testing for Color Stability of Plastics Exposedto Indoor Office Environments1This standard is issued under the fixed designation D 4674; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the basic principles and operatingprocedures for using fluorescent light t
3、o 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, Refrigerating, and
4、 Air-conditioning Engineers (ASHRAE) recommendations forworkers comfort.NOTE 1There is no equivalent ISO standard.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
5、for mixing of fluorescent lamps and two of themethods use devices that comply with Practice G 154.NOTE 2Method 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 evaluat
6、ion of the results arecovered in ASTM methods or specifications for specificmaterials. General guidance is given in Practice G 151. Morespecific information about methods for determining the changein properties after exposure and reporting these results isdescribed in Practice D 5870.1.4 The values
7、stated in SI units are to be regarded 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 th
8、e responsibility of the user of 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 7.2. Referenced Documents2.1 Specification for ASTM Standards:D 1729 Practi
9、ce for Visual Appraisal of Colors and ColorDifferences of Diffusely Illuminated Opaque Materials2D 2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinates2D 3980 Practice for Interlaboratory Testing of Paint andRelated Materials3D 5870 Pra
10、ctice for Calculating the Property RetentionIndex of Plastics4E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method5G 113 Terminology Relating to Natural and ArtificialWeathering Tests of Nonmetallic Materials6G 141 Guide for Addressing Variability in Expo
11、sure Testingon Nonmetallic Materials6G 147 Practice for Conditioning and Handling of Nonme-tallic Materials for Natural and Artificial WeatheringTests6G 151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices that Use Laboratory Light Sources6G 154 Practice for Operating Fluores
12、cent Light Apparatusfor UV Exposure of Nonmetallic Materials6G 169 Guide for Application of Basic Statistical Methods toWeathering Tests63. Terminology3.1 DefinitionsThe definitions given in TerminologyG 113 are applicable to this practice.4. Summary of Practice4.1 This practice provides for the exp
13、osure of specimens tofluorescent light under controlled environmental conditions.Radiant energy is provided by one of the following fluorescentlight sources: (1) VHO cool-white fluorescent lamps and glass1This practice is under the jurisdiction of ASTM Committee D20 on Plastics andis the direct resp
14、onsibility of Subcommittee D20.50 on Durability of Plastics.Current edition approved December 10, 2002. Published February 2003. Origi-nally approved in 1987. Last previous edition approved in 2002 as D 4674 - 02.2Annual Book of ASTM Standards,Vol06.01.3Discontinued; see 1997 Annual Book of ASTM Sta
15、ndards,Vol06.01.4Annual Book of ASTM Standards,Vol08.03.5Annual Book of ASTM Standards,Vol14.02.6Annual Book of ASTM Standards,Vol14.04.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.filtered fluorescent UV lamps, (2) VHO cool-white
16、 fluorescentlamps 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 and III are intendedto simula
17、te 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, results obtained from each meth
18、od 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 G 154.4.1.2 Do not compare Comparison of results obtained fromspecimens exposed using the methods described should not be
19、made 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 or instru-mental procedur
20、es.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 localized phenomena such as handl
21、ing, dirt contamination,etc.NOTE 5Caution: Caution: Refer to practice G 151 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 laboratory accelerated e
22、xposuretests is found in Guide G 141.5.2 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 cancause significant diff
23、erences 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 laboratories hasbeen shown to b
24、e 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 recommendedthat at least three
25、 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 G 151.6.1.1 The test chamber used for Methods I and II shall bedesigned so that simultaneous op
26、eration of VHO cool whiteand glass filtered UV fluorescent lamps is possible, and shall beequipped with a radiometer complying with the requirementsof Practice G 151 and calibrated from 250 to 400 nm. AnnexAnnex A1 contains more information about the design of theapparatus used for Methods I and II.
27、6.1.2 The test chamber used for Methods III and IV shallconform to the requirements of Practice G 154.6.2 The spectral distribution of the UVB-313, UVA-340,and UVA-351 shall comply with the requirements of practiceG 154. The spectral power distribution of the cool white lampsused shall comply with t
28、he requirements given in Annex AnnexA2.6.3 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 thedevice for at least 24
29、 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 G 154 for the area inwhich the instruments are used.6.5 Instrument Calibrat
30、ionTo 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 traceable to nationa
31、l 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 be constructed so
32、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 flatpiece 50 by 80 by 4
33、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 accordance with one o
34、f 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 theD 4674 02a2percentage of time the specimen
35、s 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) coolwhite fluorescent lamps plus intermittent radiant energy fromwindow glass filtered fluorescent UV lamps. The total UVradiant exposure from both
36、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 border around the exposure
37、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 for the desired CWEradi
38、ant 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 lampson and record the UV irr
39、adiance (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= exposure time for fluorescent
40、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 originates fromfluorescent ligh
41、ting. 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.9.1.1.7 Program the devic
42、e 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 intervals equal to25 6 5 %
43、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 line of the exposure t
44、othe 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 cause for the hightemperat
45、ure 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 conforming to the requirements
46、 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, in W/m2, 250-400 nm).Calculate the exposure time ne
47、cessary 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 exceeds 40C,the device
48、 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 tests.9.1.3 Method III:
49、9.1.3.1 Use apparatus conforming to the requirements ofPractice G 154 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 of theexposure area. I
