1、Designation: D5208 14Standard Practice forFluorescent Ultraviolet (UV) Exposure of PhotodegradablePlastics1This standard is issued under the fixed designation D5208; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 specific procedures applicablefor fluorescent Ultraviolet (UV) exposure of photodegradableplastic
3、s conducted in accordance with Practices G151 andG154. This practice also covers the preparation of test speci-mens and the evaluation of test results.1.2 Practice D4329 covers fluorescent UV exposures ofplastics intended for long term use in outdoor applications.1.3 The values stated in SI units ar
4、e to be regarded asstandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices an
5、d determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D3826 Practice for Determining Degradation End Point inDegradable Polyethylene and Polypropylene Using a Ten-sile TestD4329 Practic
6、e for Fluorescent Ultraviolet (UV) Lamp Ap-paratus Exposure of PlasticsD5870 Practice for Calculating Property Retention Index ofPlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG113 Terminology Relating to Natural and Artificial Weath-ering Tes
7、ts of Nonmetallic MaterialsG141 Guide for Addressing Variability in Exposure Testingof Nonmetallic MaterialsG147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering TestsG151 Practice for Exposing Nonmetallic Materials in Accel-erated Test Devices t
8、hat Use Laboratory Light SourcesG154 Practice for Operating Fluorescent Ultraviolet (UV)Lamp Apparatus for Exposure of Nonmetallic MaterialsG169 Guide for Application of Basic Statistical Methods toWeathering Tests3. Terminology3.1 The definitions given in Terminology G113 are appli-cable to this pr
9、actice.4. Significance and Use4.1 Materials made from photodegradable 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 proper
10、ty changes associated withconditions that might be experienced 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 pol
11、lution, biological attack, andsalt water exposure.4.2 CautionsVariation in results can be expected whenoperating conditions are varied within the accepted limits ofthis practice. Therefore, no reference to the use of this practiceshall be made unless accompanied by a report prepared inaccordance wit
12、h Section 9 that describes the specific operatingconditions used. Refer to Practice G151 for detailed informa-tion on the caveats applicable to use of results obtained inaccordance with this practice.NOTE 2Additional information on sources of variability and onstrategies for addressing variability i
13、n the design, execution and dataanalysis of laboratory accelerated exposure tests is found in Guide G141.4.3 Exposure of a similar material of known performance (acontrol) at the same time as the test specimens provides astandard for comparative purposes. Use of a control to rank thestability of tes
14、t materials greatly improves agreement between1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.96 on Environmentally DegradablePlastics and Biobased Products.Current edition approved April 1, 2014. Published April 2014. Ori
15、ginallyapproved in 1991. Last previous edition approved in 2009 as D5208 - 09. DOI:10.1520/D5208-14.2For referenced ASTM standards, 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 Do
16、cument Summary page onthe ASTM website.*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 States1different laboratories.3,4It is recommended that at least threereplicates of each
17、material evaluated 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 G154.Significant factors include regulation of line voltage, tempera-ture of the room in which the device operates,
18、 temperaturecontrol, and condition and age of the lamps, if exposure isconducted in a device without irradiance control.5. Apparatus5.1 Use of fluorescent UV apparatus that conform to therequirements defined in Practices G151 and G154 is required toconform to this practice.5.2 The spectral power dis
19、tribution of the fluorescent UVlamp shall conform to the requirements in Practice G154 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). Control of ambient temperature isparticularly critical when one apparatus is stacked abo
20、veanother, because the heat generated from the lower unit caninterfere with the operation 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 which the apparatus is located
21、 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 parties concerned.Where practic
22、al, 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 by theholder shall be cove
23、red. 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 to abacking panel made of
24、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 backing such as aluminum
25、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 G147 foridentification and conditioning and handling of specimens oftest, control, and reference materials prior
26、 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 can be obtained by this method, since themasked portion of the specimen is still exposed to temperatureand humidity cycles that, in ma
27、ny cases, will affect results.6.8 Since the thickness of a specimen can markedly affectthe results, thickness of test and control specimens shall bewithin 610 % of the nominal dimensions.NOTE 3This is especially important when mechanical properties arebeing investigated.6.9 Retain a supply of unexpo
28、sed file specimens of allmaterials tested.6.10 Specimens shall not be removed from the exposureapparatus for more than 24 h and then returned for additionaltests, since this will not produce the same results on allmaterials as tests run without this type of interruption. Reportany elapsed time as no
29、ted under Section 9.NOTE 4Since the stability of the file specimen can 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 with the file specimen are not neces-sa
30、rily valid. Instrumental measurements are recommended wheneverpossible.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 otherwise specified, control irrad
31、iance at 0.89W/(m2 nm) at 340 nm.NOTE 5In devices without irradiance control operated at 50 6 3Cuninsulated black panel temperature the typical irradiance at 340 nm is0.89 W/(m2 nm). (See Note 1 of Table X2.1 in Practice G154 for a fullexplanation of the current default irradiance.)7.2.1 During equi
32、librium operation, the allowed deviationfrom the 340 nm set point is 60.02 W/(m2 nm). If theindicated irradiance is outside the tolerance, stop the test andcorrect the problem before continuing.7.3 Unless otherwise specified, program the device to one ofthe following test cycles.7.3.1 Cycle A20 h UV
33、 (light only) with uninsulated blackpanel temperature controlled at 50C.4 h Dark/condensation with uninsulated blackpanel temperature controlled at 40C.Repeat this 24-hour cycle continuously until the desired totalexposure is reached.3Fischer, R., “Results of Round Robin Studies of Light- and Water-
34、ExposureStandard Practices,” Accelerated and Outdoor Durability Testing of OrganicMaterials, ASTM STP 1202, Warren D. Ketola and Douglas Grossman, Eds.,American Society for Testing and Materials, Philadelphia, 1993.4Ketola, W., and Fischer, R., “Characterization and Use of Reference Materialsin Acce
35、lerated Durability Tests,” VAMAS Technical Report No. 30. Available fromNIST, Gaithersburg, MD.D5208 1427.3.2 Cycle B4 h UV (light only) with uninsulated blackpanel temperature controlled at 50C.4 h Dark/condensation with uninsulated blackpanel temperature controlled at 40C.Repeat this 8-hour cycle
36、continuously until the desired totalexposure is reached.7.3.3 Cycle Ccontinuous UV with uninsulated black paneltemperature controlled at 50C. Operate continuously until thedesired total exposure is reached.7.3.4 During equilibrium operation, the maximum allow-able deviation from the uninsulated blac
37、k panel temperature setpoint is 63C. If the indicated temperature of the uninsulatedblack panel is outside these limits, stop the test and correct theproblem before continuing.NOTE 6The set points and tolerances for 7.2 and Cycles A, B, and Crepresent an operational control point for equilibrium con
38、ditions at asingle location in the cabinet, which does not necessarily represent theuniformity of those conditions throughout the cabinet. ASTM CommitteeG03 is working to refine these tolerances and address the uniformity issue.7.3.5 Use Cycle C for materials that will be used for toxicitytesting af
39、ter exposure. This is essential because cycles that usecondensation can wash away by-products of photochemicaldegradation.7.4 Unless otherwise specified, reposition specimens asfollows in order to minimize any effects from temperature orUV light variation. Figure 1 shows a diagram of the specimenrep
40、ositioning.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 area, and (2) sliding the remainingholders to the right.7.4.2 Reposition the specimens vertically so that each speci-men spends the same amou
41、nt of exposure time in each verticalposition within the specimen holder. For instance, if twospecimens are stacked vertically in each holder, then the topand bottom specimens shall switch places halfway through thetest. If four specimens are stacked vertically, then repositionthe specimens verticall
42、y three times during the test.7.5 Identification of any control specimen used shall accom-pany the report.8. Periods of Exposure and Evaluation of Test Results8.1 If a standard or specification for general use requires adefinite property level after a specific time or radiant exposurein an exposure
43、test conducted in accordance with this practice,base the specified property level on results from round-robinexperiments run to determine the test reproducibility from theexposure and property measurement procedures. Conduct theseround-robins in accordance with Practice E691 and include astatistical
44、ly representative sample of all laboratories or orga-nizations who would normally conduct the exposure andproperty measurement. The precision and bias section containsresults from such a round-robin.8.1.1 If a standard or specification for use between two orthree parties requires a definite property
45、 level after a specifictime or radiant exposure in an exposure test conducted inaccordance with this practice, base the specified property levelon two independent experiments run in each laboratory todetermine the reproducibility for the exposure and propertymeasurement process. The reproducibility
46、of the exposure/property measurement process is then used to determine theminimum level of property after the exposure that is mutuallyagreeable to all parties.8.2 When reproducibility in results from an exposure testconducted in accordance with this practice have not beenestablished through round-r
47、obin testing, specify performancerequirements for materials in terms of comparison (ranked) toa control material. The control 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 anal
48、ysis of variance to determine whetherany differences between test materials and control materials arestatistically significant. Expose replicates of the test specimenand the control specimen so that statistically significant per-formance differences can be determined.NOTE 7Fischer illustrates use of
49、 rank comparison between test andcontrol materials in specifications.5NOTE 8Guide G169 includes examples showing use of analysis 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 a
