1、Designation: D 5272 08Standard Practice forOutdoor Exposure Testing of Photodegradable Plastics1This standard is issued under the fixed designation D 5272; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、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 D 1435 and G7 are employed for the outdoorexposure testing of photodeg
3、radable 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 limitations prior to us
4、e.NOTE 1There is no ISO standard that is equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D 882 Test Method for Tensile Properties of Thin PlasticSheetingD 883 Terminology Relating to PlasticsD 1435 Practice for Outdoor Weathering of PlasticsD 3593 Test Method for Molecular Wei
5、ght Averages andMolecular Weight Distribution of Certain Polymers byLiquid Size-Exclusion Chromatography (Gel PermeationChromatography GPC) Using Universal Calibration3D 3826 Practice for Determining Degradation End Point inDegradable Polyethylene and Polypropylene Using a Ten-sile TestE 772 Termino
6、logy Relating to Solar Energy ConversionG7 Practice for Atmospheric Environmental ExposureTesting of Nonmetallic MaterialsG 169 Guide forApplication of Basic Statistical Methods toWeathering TestsG 183 Practice for Field Use of Pyranometers, Pyrheliom-eters and UV Radiometers3. Terminology3.1 The te
7、rminology given in Terminology E 772 and Ter-minology D 883 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 5exp
8、osure angle 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
9、year. This 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
10、 average of 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
11、 of daylight and solar-ultraviolet radiation, there are significant differences in tem-perature, and moisture stresses between different locations, andbetween different years, or periods within a single year, at asingle location. Because of this variability, results from this testcannot be used to p
12、redict the absolute rate at which photode-gradable plastics degrade. Results from this test can be used tocompare relative rates of degradation for materials exposed atthe same time in the same location. Results from multipleexposures of a common lot of material (during differentseasons over several
13、 years) at different sites can be used to1This 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 Aug. 1, 2008. Published September 2008. Origi
14、nallyapproved in 1992. Last previous edition approved in 1999 as D 5272 - 92(1999).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 Document Summary pa
15、ge onthe ASTM website.3Withdrawn4Daro,A., et al, “Degradation of Polymer Blends IV, Natural Weathering of LowDensity and Linear 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 Outd
16、oor Weathering of Materials,” Society ofAutomotive Engineers,SAE Technical Paper Number 850348 , 1985 .1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Spare the relative rates at which a particular photodegrad-able plastic will degrade in e
17、ach location.NOTE 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 samesolar-ultraviolet radiation increment will not necessarily give the samechan
18、ges 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 characteristics of the exposure site as well.4.4 Where measurement of total sola
19、r-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 established must be exposed at the same time as theother materials being tested. The
20、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 reference materials when exposure length is determined bytotal solar or solar
21、UV radiant exposure.NOTE 3Areference 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 be character-ized and certified by a recognized standards agency or group.5. Ap
22、paratus5.1 Use exposure racks constructed in accordance with therequirements of Practice G7. Unless otherwise specified,position the exposure racks so that specimens face the equatorand so that the exposed surfaces are 5 from the horizontal. Ifother exposure rack orientations are used, they must ber
23、eported.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 meshexpanded-metal (aluminum or stainless steel) sheet backing.Use 1618 gage metal with
24、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-als used for the mounting bars. Fig. 1 is a top view showingtypical rack construction
25、.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 produce sharpedges and damage exposed specimens. Medium-density over-lay (MDO) or high
26、-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. Degradation rates from exposures using Rack B willbe somewhat faster than those u
27、sing 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 Ultraviolet RadiometerUnless otherwise specified,use a total UV radiometer that measures ultr
28、aviolet radiationfrom 295 to 385 mm. Operate the radiometer in accordancewith Practice G 183. Narrow band radiometers (for example,with 20 nm bandpass) can also be used if agreed upon by allinterested parties. Operate narrow band radiometers in accor-dance with Practice G 183.NOTE 5The use of narrow
29、 band filter UV radiometers having selec-tive spectral 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 photodegradation of the plastic material, whichis a result of a complex interaction of
30、 many factors, including sensitivityacross a broad wavelength region.FIG. 1 Typical Rack Construction for Exterior Exposures of Photodegradable PlasticsD52720826. Sampling6.1 Sample using a statistically acceptable procedure agreedupon by interested parties.7. Procedure7.1 Attach the ends of specime
31、ns of photodegradable plasticto be exposed to the positionable mounting bars or plywoodrack. Films or specimens that are nearly flat can be attachedusing a pressure sensitive tape with a durable adhesive andbacking. Staples may be used with plywood racks or withwood mounting bars. Specimens with odd
32、 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 identifying number, letter, or symbol.Expose at least three replicate specimens for each m
33、aterial 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 exposure rack.7.2 Ensure that the UV radiometer is mounted at an angle of5 from the horizon
34、tal, 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 prescribed level of total solar-ultravioletradiation. It is recommended that a series of ex
35、posure 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 solar-ultraviolet radiation incident on 5surfaces in representative humid subtropical and
36、 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 exposures in joules per square metre, with datareported to four significant figures. If agree
37、d 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 employed to follow exposure increments.7.5 After specimens are exposed for the desired amou
38、nt oftotal solar-ultraviolet radiation, measure the specified propertyor properties. Typical properties measured are molecularweight (in accordance with Test Method D 3593) and tensilestrength and elongation (in accordance with Test MethodsD 882). For polyolefins, degree of oxidation can be monitore
39、dusing 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). The degradation end pointof polyolefins can be determined by a tensile test in accord
40、ancewith Practice D 3826. 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 materials as a function ofthe time to produce a specific degree of degradation in the
41、reference material.NOTE 7Guide G 169 provides information about using statisticalanalysis techniques to compare properties of exposed and unexposedspecimens.8. Report8.1 Report the following information for each materialexposed:8.1.1 Complete identification and description (for example,dimensions) o
42、f 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, ormonths).8.1.4 Solar-ultraviolet radiant exposure:8.1.4.1 If total ultraviolet radiati
43、on 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 used to char-acterize the properties on unexposed samples of each materialbeing expos
44、ed.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 replicate specimens.8.1.7 Complete description or reference to characterizationtests u
45、sed 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 specific propertiesbeing measured. The precision and bias for the individual testmethod
46、s can be used in the analysis of data from exposuresused to assess the differences in materials.TABLE 1 Average Monthly Solar-Ultraviolet Radiation (295 to 385nm) on a 5 SurfaceANOTEThe climate data for Miami also meets the criteria for a tropicalsummer rain climate given in the Koppen Climate Class
47、ification System.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 37.7September 24.7 32.1
48、October 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.D52720839.2 Because of the variability in solar radiation, tempera-ture, and moisture levels between sites and between diffe
49、renttimes at the same site, results from this practice should only beused to compare relative rates of degradation for materialsexposed at the same time in the same location using the sameexposure 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 mentionedin this standard. Users of this standard are expressly advised that determination o
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