1、Designation: D 5208 01Standard Practice forFluorescent Ultraviolet (UV) Exposure of PhotodegradablePlastics1This standard is issued under the fixed designation D 5208; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t 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. Scope *1.1 This practice covers the specific procedures applicablefor fluorescent Ultraviolet (UV) exposure of photodegradablepla
3、stics conducted in accordance with Practices G 151 andG 154. This practice also covers the preparation of test speci-mens and the evaluation of test results.NOTE 1Previous versions of this practice referenced fluorescent UVdevices described by Practice G 53, which described very specificequipment de
4、signs. Practice G 53 has been withdrawn and replaced byPractice G 151, which describes performance criteria for all exposuredevices that use laboratory light sources and by Practice G 154, whichgives requirements for exposing nonmetallic materials in fluorescent UVdevices.1.2 Practice D 4329 covers
5、fluorescent UV exposures ofplastics intended for long term use in outdoor applications.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety problems, if any, associa
6、ted with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 2There is no ISO standard equivalent to this practice.2. Referenced Documents2.1 ASTM Standards:D
7、3826 Practice for Determining Degradation End Point inDegradable Polyolefins Using a Tensile Test2D 3980 Practice for Interlaboratory Testing of Paint andRelated Materials3D 5870 Practice for Calculating the Property RetentionIndex of Plastics4E 691 Practice for Conducting an Interlaboratory Study t
8、oDetermine the Precision of a Test Method5G 53 Practice for Operating Light- and Water-ExposureApparatus (Fluorescent UV/Condensation Type) for Expo-sure of Nonmetallic Materials6G 113 Terminology Relating to Natural and ArtificialWeathering Tests of Nonmetallic Materials7G 141 Guide for Addressing
9、Variability in Exposure Testingon Nonmetallic Materials7G 147 Practice for Conditioning and Handling of Nonme-tallic Materials for Natural and Artificial Weathering Tests7G 151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices that Use Laboratory Light Sources7G 154 Practice f
10、or Operating Fluorescent Light Apparatusfor UV Exposure of Nonmetallic Materials7G 169 Guide for Application of Basic Statistical Methods toWeathering Tests73. Terminology3.1 The definitions given in Terminology G 113 are appli-cable to this practice.4. Significance and Use4.1 Materials made from ph
11、otodegradable plastics are in-tended to show relatively rapid deterioration of chemical,physical, and mechanical properties when exposed to light,heat, and water after fulfilling their intended purpose. Thispractice is intended to induce property changes associated withconditions that might be exper
12、ienced when the material isdiscarded as litter, including the effects of sunlight, moisture,and heat. The exposure used in this practice is not intended tosimulate the deterioration caused by localized weather phe-nomena such as atmospheric pollution, biological attack, andsalt water exposure.4.2 Ca
13、utions Variation in results may be expected whenoperating conditions are varied within the accepted limits ofthis practice. Therefore, no reference to the use of this practiceshould be made unless accompanied by a report prepared in1This practice is under the jurisdiction of ASTM Committee D20 on Pl
14、astics andis the direct responsibility of Subcommittee D20.96 on Environmentally DegradablePlastics.Current edition approved December 10, 2001. Published February 2002. Origi-nally published as D 5208 91. Discontinued February 2000 and reinstated asD 5208 01.2Annual Book of ASTM Standards, Vol 08.02
15、.3Discontinued; see 1997 Annual Book of ASTM Standards, Vol 06.01.4Annual Book of ASTM Standards, Vol 08.03.5Annual Book of ASTM Standards, Vol 14.02.6Discontinued; see 2001 Annual Book of ASTM Standards, Vol 14.04.7Annual Book of ASTM Standards, Vol 14.04.1*A Summary of Changes section appears at t
16、he end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.accordance with Section 9 that describes the specific operatingconditions used. Refer to Practice G 151 for detailed informa-tion on the caveats applicable to use
17、 of results obtained inaccordance with this practice.NOTE 3Additional information on sources of variability and onstrategies for addressing variability in the design, execution and dataanalysis of laboratory accelerated exposure tests is found in Guide G 141.4.3 Exposure of a similar material of kno
18、wn performance (acontrol) at the same time as the test specimens provides astandard for comparative purposes. Use of a control to rank thestability of test materials greatly improves agreement betweendifferent laboratories.8,9It is recommended that at least threereplicates of each material evaluated
19、 be exposed to allow forstatistical evaluation of results.4.4 Test results will depend upon the care that is taken tooperate the equipment in accordance with Practice G 154.Significant factors include regulation of line voltage, tempera-ture of the room in which the device operates, temperaturecontr
20、ol, and condition and age of the lamps.5. Apparatus5.1 Use of fluorescent UV apparatus that conform to therequirements defined in Practices G 151 and G 154 is requiredto conform to this practice.5.2 The spectral power distribution of the fluorescent UVlamp shall conform to the requirements in Practi
21、ce G 154 for aUVA 340 lamp.5.3 Test Chamber Location:5.3.1 Locate the apparatus in an area maintained between 18and 27C (65 and 80F). Measure ambient temperature at amaximum distance of 150 mm (6 in.) from the plane door ofthe apparatus. Control of ambient temperature is particularlycritical when on
22、e apparatus is stacked above another, becausethe heat generated from the lower unit can interfere with theoperation of the units above.5.3.2 Place the apparatus at least 300 mm from walls orother apparatus. Do not place the apparatus near a heat sourcesuch as an oven.5.3.3 Ventilate the room in whic
23、h the apparatus is located toremove heat and moisture.6. Test Specimens6.1 The size and shape of specimens to be exposed will bedetermined by the specifications of the particular test methodused to evaluate the effects of the exposure on the specimens;the test method shall be determined by the parti
24、es concerned.Where practical, it is recommended that specimens be sized tofit specimen holders and racks supplied with the exposureapparatus. Unless supplied with a specific backing as anintegral part of the test, specimens shall be mounted so thatonly the minimum specimen area required for support
25、by theholder shall be covered. This unexposed surface must not beused as part of the test area.6.2 For specimens of insulating materials, such as foams,maximum specimen thickness is 20 mm in order to allow foradequate heat transfer for condensation.6.3 To provide rigidity, attach flexible specimens
26、to abacking panel made of aluminum, 0.635 mm (0.025 mm) thick.Suggested aluminum alloys are 5052, 6061, or 3003.6.4 Seal any holes in specimens larger than two mm and anyopenings larger than one mm around irregularly shaped speci-mens to prevent loss of water vapor. Attach porous specimensto a solid
27、 backing such as aluminum that can act as a vaporbarrier.6.5 Unless otherwise specified, expose at least three repli-cate specimens of each test and control material.6.6 Follow the procedures described in Practice G 147 foridentification and conditioning and handling of specimens oftest, control, an
28、d reference materials prior to, during, and afterexposure.6.7 Do not mask the face of a specimen for the purpose ofshowing on one panel the effects of various exposure times.Misleading results may be obtained by this method, since themasked portion of the specimen is still exposed to temperatureand
29、humidity cycles that, in many cases, will affect results.6.8 Since the thickness of a specimen may markedly affectthe results, thickness of test and control specimens shall bewithin 610 % of the nominal dimensions.NOTE 4This is especially important when mechanical properties arebeing investigated.6.
30、9 Retain a supply of unexposed file specimens of allmaterials tested.6.10 Specimens should not be removed from the exposureapparatus for more than 24 h and then returned for additionaltests, since this may not produce the same results on allmaterials as tests run without this type of interruption. A
31、nyelapsed time should be reported as noted under Section 9.NOTE 5Since the stability of the file specimen may also be time-dependent, users are cautioned that over prolonged exposure periods, orwhere small differences in the order of acceptable limits are anticipated,comparison of exposed specimens
32、with the file specimen may not be valid.Instrumental measurements are recommended whenever possible.7. Procedure7.1 When the test and control specimens do not completelyfill the specimen racks, fill all empty spaces with blank panelsto maintain the test conditions within the chamber.7.2 Unless other
33、wise specified, control irradiance at 0.78 60.02 W/(m2 nm) at 340 nm.NOTE 6In devices without irradiance control operated at 50 6 3Cuninsulated black panel temperature the irradiance at 340 nm is 0.78 60.12 W/(m2 nm).7.3 Unless otherwise specified, program the device to one ofthe following test cycl
34、es. Operate the device continuously.7.3.1 Cycle A20 h UV with uninsulated black paneltemperature controlled at 50 6 3C.4 h condensation with uninsulated blackpanel temperature controlled at 40 6 3C.8Fischer, R., “Results of Round Robin Studies of Light- and Water-ExposureStandard Practices,” Acceler
35、ated and Outdoor Durability Testing of OrganicMaterials, ASTM STP 1202, Warren D. Ketola and Douglas Grossman, Eds.,American Society for Testing and Materials, Philadelphia, 1993.9Ketola, W., and Fischer, R., “Characterization and Use of Reference Materialsin Accelerated Durability Tests,” VAMAS Tec
36、hnical Report No. 30. Available fromNIST, Gaithersburg, MD.D52080127.3.2 Cycle B4 h UV with uninsulated black panel tem-perature controlled at 50 6 3C.4 h condensation with uninsulated blackpanel temperature controlled at 40 6 3C.7.3.3 Cycle Ccontinuous UV with uninsulated blackpanel temperature con
37、trolled at 50 6 3C.NOTE 7The set points and tolerances for 7.2 and Cycles A, B, and Crepresent an operational control point for equilibrium conditions at asingle location in the cabinet which may not necessarily represent theuniformity of those conditions throughout the cabinet. ASTM CommitteeG03 is
38、 working to refine these tolerances and address the uniformity issue.7.3.4 Use Cycle C for materials that will be used for toxicitytesting after exposure. This is essential because cycles that usecondensation may wash away by-products of photochemicaldegradation.7.4 Unless otherwise specified, repos
39、ition specimens asfollows in order to minimize any effects from temperature orUV light variation. Figure 1 shows a diagram of the specimenrepositioning.7.4.1 Reposition the specimens horizontally at least everythird day by (1) moving the two extreme right hand holders tothe far left of the exposure
40、area, and (2) sliding the remainingholders to the right.7.4.2 Reposition the specimens vertically so that each speci-men spends the same amount of exposure time in each verticalposition within the specimen holder. For instance, if twospecimens are stacked vertically in each holder, then the topand b
41、ottom specimens should switch places halfway throughthe test. If four specimens are stacked vertically, then thespecimens should be repositioned vertically three times duringthe test.7.5 Identification of any control specimen used shall accom-pany the report.8. Periods of Exposure and Evaluation of
42、Test Results8.1 If a standard or specification for general use requires adefinite property level after a specific time or radiant exposurein an exposure test conducted in accordance with this practice,base the specified property level on results from round-robinexperiments run to determine the test
43、reproducibility from theexposure and property measurement procedures. Conduct theseround-robins in accordance with Practice E 691 or Test MethodD 3980 and include a statistically representative sample of alllaboratories or organizations who would normally conduct theexposure and property measurement
44、. The precision and biassection contains results from such a round-robin.8.1.1 If a standard or specification for use between two orthree parties requires a definite property level after a specifictime or radiant exposure in an exposure test conducted inaccordance with this practice, base the specif
45、ied property levelon two independent experiments run in each laboratory todetermine the reproducibility for the exposure and propertymeasurement process. The reproducibility of the exposure/property measurement process is then used to determine theminimum level of property after the exposure that is
46、 mutuallyagreeable to all parties.8.2 When reproducibility in results from an exposure testconducted in accordance with this practice have not beenestablished through round-robin testing, specify performancerequirements for materials in terms of comparison (ranked) toa control material. The control
47、specimens shall be exposedsimultaneously with the test specimen(s) in the same device.All concerned parties must agree on the specific controlmaterial used.8.2.1 Conduct analysis of variance to determine whetherany differences between test materials and control materials arestatistically significant
48、. Expose replicates of the test specimenand the control specimen so that statistically significant per-formance differences can be determined.NOTE 8Fischer illustrates use of rank comparison between test andcontrol materials in specifications.10NOTE 9Guide G 169 includes examples showing use of anal
49、ysis ofvariance to compare materials.8.3 In most cases, periodic evaluation of test and controlmaterials is necessary to determine the variation in magnitudeand direction of property change as a function of exposure timeor radiant exposure.8.4 The time or radiant exposure necessary to produce adefined change in a material property can be used to evaluateor rank the stability of materials. This method is preferred overevaluating materials after an arbitrary exposure time or radiantexposure.8.4.1 Exposure to an arbitrary time or radiant exposure maybe used for the
