1、Designation: D5272 08 (Reapproved 2013)Standard Practice forOutdoor Exposure Testing of Photodegradable Plastics1This standard is issued under the fixed designation D5272; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 defines test conditions applicable whenPractices D1435 and G7 are employed for the outdoor expo-sure te
3、sting of photodegradable plastics.1.2 This standard does not purport to address all of thesafety concerns, if any, associated 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 limita
4、tions prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D882 Test Method for Tensile Properties of Thin PlasticSheetingD883 Terminology Relating to PlasticsD1435 Practice for Outdoor Weathering of PlasticsD3593 Test Method for Molecular W
5、eight Averages/ Distri-bution of Certain Polymers by Liquid Size-ExclusionChromatography (Gel Permeation Chromatography GPC)Using Universal Calibration (Withdrawn 1993)3D3826 Practice for Determining Degradation End Point inDegradable Polyethylene and Polypropylene Using a Ten-sile TestE772 Terminol
6、ogy of Solar Energy ConversionG7 Practice for Atmospheric Environmental Exposure Test-ing of Nonmetallic MaterialsG169 Guide for Application of Basic Statistical Methods toWeathering TestsG183 Practice for Field Use of Pyranometers, Pyrheliom-eters and UV Radiometers3. Terminology3.1 The terminology
7、 given in Terminology E772 and Ter-minology D883 is applicable to this practice.4. Significance and Use4.1 When discarded as litter, articles made using photode-gradable plastics are subject to attack by daylight (particularlysolar-ultraviolet radiation), oxygen, heat, and water. The 5exposure angle
8、 used in this practice represents typical condi-tions for degradation experienced by litter.4.2 This practice requires characterization of the duration ofexposure in terms of solar-ultraviolet radiation. Solar-ultraviolet radiation varies considerably as a function oflocation and time of year. This
9、can cause dramatic differencesin the time required to produce a specified level of degradationin a polymer. Daro4has shown that when the same lot ofpolyethylene containing an iron-salt prodegradant is exposed atvarious times of the year in a single location, the time requiredto produce an average of
10、 two chain scissions per moleculevaried by over 130 %. Daro, and Zerlaut and Anderson5haveshown that this variability can be significantly reduced whentotal solar or solar-ultraviolet radiation, or both, is used tocharacterize the exposure increments.4.3 In addition to variations in level of dayligh
11、t and solar-ultraviolet radiation, there are significant differences intemperature, and moisture stresses between different locations,and between different years, or periods within a single year, ata single location. Because of this variability, results from thistest cannot be used to predict the ab
12、solute rate at whichphotodegradable plastics degrade. Results from this test can beused to compare relative rates of degradation for materialsexposed at the same time in the same location. Results frommultiple exposures of a common lot of material (duringdifferent seasons over several years) at diff
13、erent sites can beused to compare the relative rates at which a particularphotodegradable plastic will degrade in each location.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.96 on Environmentally DegradablePlastics and B
14、iobased Products.Current edition approved April 1, 2013. Published April 2013. Originallyapproved in 1992. Last previous edition approved in 2008 as D5272 - 08. DOI:10.1520/D5272-08R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceast
15、m.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Daro,A., et al, “Degradation of Polymer Blends IV, Natural Weathering of LowDensity and Lin
16、ear Low Density Polyethylene,” European Polymer Journal, Vol 26,No. 1, 1990, pp. 4752.5Zerlaut, G. L., and Anderson, T. A., “Ultraviolet Radiation as a TimingTechnique for Outdoor Weathering of Materials,” Society ofAutomotive Engineers,SAE Technical Paper Number 850348 , 1985.Copyright ASTM Interna
17、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 2An inherent limitation in solar-radiation measurements is thatthey do not reflect the effects of variations in temperature and moistureexposure, which often can be as important as solar radiation. The s
18、amesolar-ultraviolet radiation increment will not necessarily give the samechanges in properties of the test specimen in different exposure sites.Results from this practice must be regarded as giving only a generalindication of the degree of degradability and should always be consideredin terms of c
19、haracteristics of the exposure site as well.4.4 Where measurement of total solar-ultraviolet radiationis not possible, exposure duration can be determined by thenumber of days, weeks, or months exposed. When this practiceis used, a reference material whose degradation properties havebeen well establ
20、ished must be exposed at the same time as theother materials being tested. The reference material used mustbe agreed upon by all interested parties. The time to produce aspecified level of degradation for each material in this simul-taneous exposure is then compared. It is also a good practice touse
21、 reference materials when exposure length is determined bytotal solar or solar UV radiant exposure.NOTE 3A reference material can be a single lot of material which hasshown consistent results after a number of exposures. It is not necessarythat the composition or properties of the reference material
22、 be character-ized and certified by a recognized standards agency or group.5. Apparatus5.1 Use exposure racks constructed in accordance with therequirements of Practice G7. Unless otherwise specified, posi-tion the exposure racks so that specimens face the equator andso that the exposed surfaces are
23、 5 from the horizontal. If otherexposure rack orientations are used, they must be reported.5.2 Use one of the following rack constructions for expos-ing photodegradable plastic specimens:5.2.1 Exposure Rack APositionable mounting bars usedfor attaching specimens shall be arrayed over a regular meshe
24、xpanded-metal (aluminum or stainless steel) sheet backing.Use 1618 gage metal with approximately 0.5-in. openings. Itis recommended that the surface area of the expanded metal be60 to 70 % open. Use a noncorroding material for the mountingbars. 6061T6 aluminum or untreated wood are typical materi-al
25、s used for the mounting bars. Fig. 1 is a top view showingtypical rack construction.5.2.2 Exposure Rack BUnpainted exterior-grade plywoodforms the rack surface to which specimens are directly at-tached. Replace the plywood when there is any evidence ofdelamination or fiber separation which could pro
26、duce sharpedges and damage exposed specimens. Medium-density over-lay (MDO) or high-density overlay (HDO) plywood aresatisfactory substrates and will require less frequent replace-ment than plywood with no overlay.NOTE 4There is less air circulation around the specimens when RackB exposures are used
27、. Degradation rates from exposures using Rack B willbe somewhat faster than those using Rack A because specimen tempera-tures will be higher. Comparisons between materials should only be madewith exposures conducted at the same time and using the same rack type.5.3 Solar Radiometers:5.3.1 Ultraviole
28、t RadiometerUnless otherwise specified,use a total UV radiometer that measures ultraviolet radiationfrom 295 to 385 mm. Operate the radiometer in accordancewith Practice G183. Narrow band radiometers (for example,with 20 nm bandpass) can also be used if agreed upon by allinterested parties. Operate
29、narrow band radiometers in accor-dance with Practice G183.NOTE 5The use of narrow band filter UVradiometers having selectivespectral sensitivity may not be sensitive to all variations of solar-ultraviolet radiation. Monitoring at a narrow band (for example, 20 nm)may not relate to the total photodeg
30、radation of the plastic material, whichis a result of a complex interaction of many factors, including sensitivityacross a broad wavelength region.6. Sampling6.1 Sample using a statistically acceptable procedure agreedupon by interested parties.7. Procedure7.1 Attach the ends of specimens of photode
31、gradable plasticto be exposed to the positionable mounting bars or plywoodFIG. 1 Typical Rack Construction for Exterior Exposures of Photodegradable PlasticsD5272 08 (2013)2rack. Films or specimens that are nearly flat can be attachedusing a pressure sensitive tape with a durable adhesive andbacking
32、. Staples may be used with plywood racks or withwood mounting bars. Specimens with odd shapes can beattached directly to the expanded metal or plywood usingnonferrous bolts and large washers or by any other suitablemethod. Ensure that the test specimens are inscribed orotherwise labeled with an iden
33、tifying number, letter, or symbol.Expose at least three replicate specimens for each material andexposure increment used.NOTE 6Pressure sensitive tapes with aluminum foil backing andacrylic pressure sensitive adhesives have been found to be suitable forattaching flat films and specimens to the expos
34、ure rack.7.2 Ensure that the UV radiometer is mounted at an angle of5 from the horizontal, facing the equator. If specimens areexposed at a different angle, mount the UV radiometer at thesame angle as the specimens.7.3 Mount the specimens on the exposure rack for the timedesired to produce the presc
35、ribed level of total solar-ultravioletradiation. It is recommended that a series of exposure incre-ments be used for each material being tested to determine therate of degradation as a function of total solar or solar-ultraviolet radiant energy dose. Table 1 shows monthly andannual average total sol
36、ar-ultraviolet radiation incident on 5surfaces in representative humid subtropical and desert cli-mates.7.4 If total ultraviolet radiant energy is used to determineexposure increments, measure the increments using the instru-mentation in accordance with 5.3.1. Express total solar-ultraviolet exposur
37、es in joules per square metre, with datareported to four significant figures. If agreed on by allinterested parties, the ultraviolet radiant energy in specifiednarrow wavelength intervals (or bands) that closely conform tospectral regions where the plastic material is most sensitivemay also be emplo
38、yed to follow exposure increments.7.5 After specimens are exposed for the desired amount oftotal solar-ultraviolet radiation, measure the specified propertyor properties. Typical properties measured are molecularweight (in accordance with Test Method D3593) and tensilestrength and elongation (in acc
39、ordance with Test MethodsD882). For polyolefins, degree of oxidation can be monitoredusing a carbonyl index, which is the ratio of carbonyl infraredabsorbance at approximately 1715 cm1to an invariant absor-bance characteristic of the polymer (for example, C-H stretchat approximately 30002840 cm1). T
40、he degradation end pointof polyolefins can be determined by a tensile test in accordancewith Practice D3826. Measure the same properties of anunexposed specimen of each material being tested. If areference material is used, determine its properties and expressthe time to degradation for all other ma
41、terials as a function ofthe time to produce a specific degree of degradation in thereference material.NOTE 7Guide G169 provides information about using statisticalanalysis techniques to compare properties of exposed and unexposedspecimens.8. Report8.1 Report the following information for each materi
42、alexposed:8.1.1 Complete identification and description (for example,dimensions) of material tested.8.1.2 Location of exposure and type of exposure rack used.8.1.2.1 Any exposure angle other than 5.8.1.3 Dates exposure started and completed.8.1.3.1 Total time exposed (expressed in days, weeks, ormon
43、ths).8.1.4 Solar-ultraviolet radiant exposure:8.1.4.1 If total ultraviolet radiation is used, it shall beexpressed in joules per square metre. Record manufacturer andmodel of UV radiometer employed, date of last calibration, andcalibrating laboratory.8.1.5 General appearance and results of tests use
44、d to char-acterize the properties on unexposed samples of each materialbeing exposed.8.1.6 General appearance and results of tests used to char-acterize the properties of specimens from each exposureincrement. Report the average and standard deviation fromeach test used to measure properties of repl
45、icate specimens.8.1.7 Complete description or reference to characterizationtests used to evaluate material properties.9. Precision and Bias9.1 It is not practicable to specify the precision of theprocedure in this practice because it is dependent upon theASTM test methods used to determine the speci
46、fic propertiesbeing measured. The precision and bias for the individual testmethods can be used in the analysis of data from exposuresused to assess the differences in materials.9.2 Because of the variability in solar radiation,temperature, and moisture levels between sites and betweendifferent time
47、s at the same site, results from this practiceshould only be used to compare relative rates of degradationTABLE 1 Average Monthly Solar-Ultraviolet Radiation (295 to 385nm) on a 5 SurfaceANOTE 1The climate data for Miami also meets the criteria for atropical summer rain climate given in the Koppen C
48、limate ClassificationSystem.MonthAverage Solar-Ultraviolet Radiation (MJ/m2, 295385 nm)Subtropical ClimateMiami, FL (26N latitude)Desert ClimatePhoenix, AZ (34N latitude)January 19.6 16.6February 21.6 19.5March 28.4 29.0April 32.2 36.1May 33.3 41.1June 28.6 41.7July 29.8 40.3August 27.6 37.7Septembe
49、r 24.7 32.1October 23.5 25.7November 18.7 18.0December 17.5 15.3Annual 305.5 352.5AData in this table are the averages for monthly total solar UV radiation datareported from 1985 to 2005.D5272 08 (2013)3for materials exposed at the same time in the same locationusing the same exposure rack construction.10. Keywords10.1 aging; degradable plastic; exterior exposure; outdoorexposure; photodegradation; ultraviolet radiation; weatheringASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedi
