ASTM D5272-92(1999)
(Practice)Standard Practice for Outdoor Exposure Testing of Photodegradable Plastics
Standard Practice for Outdoor Exposure Testing of Photodegradable Plastics
SCOPE
1.1 This practice defines test conditions applicable when Practices D1435 and G7 are employed for the outdoor exposure testing of photodegradable plastics.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Note 1-There is no ISO standard that is equivalent to this standard.
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Designation:D5272–92 (Reapproved 1999)
Standard Practice for
Outdoor Exposure Testing of Photodegradable Plastics
This standard is issued under the fixed designation D5272; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope exposure angle used in this practice represents typical condi-
tions for degradation experienced by litter.
1.1 This practice defines test conditions applicable when
4.2 Thispracticerequirescharacterizationofthedurationof
Practices D1435 and G7 are employed for the outdoor
exposure in terms of solar-ultraviolet radiation. Solar-
exposure testing of photodegradable plastics.
ultraviolet radiation varies considerably as a function of
1.2 This standard does not purport to address all of the
location and time of year. This can cause dramatic differences
safety concerns, if any, associated with its use. It is the
inthetimerequiredtoproduceaspecifiedlevelofdegradation
responsibility of the user of this standard to establish appro-
in a polymer. Daro has shown that when the same lot of
priate safety and health practices and determine the applica-
polyethylenecontaininganiron-saltprodegradantisexposedat
bility of regulatory limitations prior to use.
various times of the year in a single location, the time required
NOTE 1—There is no ISO standard that is equivalent to this standard.
to produce an average of two chain scissions per molecule
varied by over 130%. Daro, and Zerlaut and Anderson have
2. Referenced Documents
shown that this variability can be significantly reduced when
2.1 ASTM Standards:
total solar or solar-ultraviolet radiation, or both, is used to
D882 Test Methods for Tensile Properties of Thin Plastic
characterize the exposure increments.
Sheeting
4.3 In addition to variations in level of daylight and solar-
D883 Terminology Relating to Plastics
ultraviolet radiation, there are significant differences in tem-
D1435 Practice for Outdoor Weathering of Plastics
perature,andmoisturestressesbetweendifferentlocations,and
D1898 Practice for Sampling of Plastics
between different years, or periods within a single year, at a
D3593 Test Method for Molecular Weight Averages and
singlelocation.Becauseofthisvariability,resultsfromthistest
Molecular Weight Distribution of Certain Polymers by
cannot be used to predict the absolute rate at which photode-
Liquid Size-Exclusion Chromatography (Gel Permeation
gradable plastics degrade. Results from this test can be used to
Chromatograph GPC) Using Universal Calibration
compare relative rates of degradation for materials exposed at
D3826 Practice for Determining Degradation End Point in
the same time in the same location. Results from multiple
Degradable Polyolefins Using a Tensile Test
exposures of a common lot of material (during different
E772 Terminology Relating to Solar Energy Conversion
seasons over several years) at different sites can be used to
G 7 Practice for Atmospheric Environmental Exposure
compare the relative rates at which a particular photodegrad-
Testing of Nonmetallic Materials
able plastic will degrade in each location.
3. Terminology
NOTE 2—Aninherentlimitationinsolar-radiationmeasurementsisthat
they do not reflect the effects of variations in temperature and moisture
3.1 The terminology given in Terminology E772 and Ter-
exposure, which often can be as important as solar radiation. The same
minology D883 is applicable to this practice.
solar-ultraviolet radiation increment will not necessarily give the same
changes in properties of the test specimen in different exposure sites.
4. Significance and Use
Results from this practice must be regarded as giving only a general
4.1 When discarded as litter, articles made using photode-
indication of the degree of degradability and should always be considered
gradable plastics are subject to attack by daylight (particularly in terms of characteristics of the exposure site as well.
solar-ultraviolet radiation), oxygen, heat, and water. The 5°
4.4 Where measurement of total solar-ultraviolet radiation
is not possible, exposure duration can be determined by the
This practice is under the jurisdiction of ASTM Committee D-20 on Plastics
and is the direct responsibility of Subcommittee D20.96 on Environmentally
Degradable Plastics. Daro,A.,etal,“DegradationofPolymerBlendsIV,NaturalWeatheringofLow
Current edition approved July 15, 1992. Published September 1992. DensityandLinearLowDensityPolyethylene,”EuropeanPolymerJournal,Vol26,
Annual Book of ASTM Standards, Vol 08.01. No. 1, 1990, pp. 47–52.
3 7
Annual Book of ASTM Standards, Vol 08.02. Zerlaut, G. L., and Anderson, T. A., “Ultraviolet Radiation as a Timing
Annual Book of ASTM Standards, Vol 12.02. TechniqueforOutdoorWeatheringofMaterials,”SocietyofAutomotiveEngineers,
Annual Book of ASTM Standards, Vol 14.02. SAE Technical Paper Number 850348, 1985.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5272
FIG. 1 Typical Rack Construction for Exterior Exposures of Photodegradable Plastics
numberofdays,weeks,ormonthsexposed.Whenthispractice lay (MDO) or high-density overlay (HDO) plywood are
isused,areferencematerialwhosedegradationpropertieshave satisfactory substrates and will require less frequent replace-
been well established must be exposed at the same time as the ment than plywood with no overlay.
other materials being tested. The reference material used must
NOTE 4—There is less air circulation around the specimens when Rack
be agreed upon by all interested parties.The time to produce a
Bexposuresareused.DegradationratesfromexposuresusingRackBwill
specified level of degradation for each material in this simul-
be somewhat faster than those using Rack A because specimen tempera-
taneousexposureisthencompared.Itisalsoagoodpracticeto
tures will be higher. Comparisons between materials should only be made
with exposures conducted at the same time and using the same rack type.
usereferencematerialswhenexposurelengthisdeterminedby
total solar or solar UV radiant exposure.
5.3 Solar Radiometers:
5.3.1 Ultraviolet Radiometer—A total ultraviolet (UV) ra-
NOTE 3—Areference material can be a single lot of material which has
shown consistent results after a number of exposures. It is not necessary diometer that measures ultraviolet radiation in the wavelength
that the composition or properties of the reference material be character-
region from 295 to 385 nm should be used. Calibrate the
ized and certified by a recognized standards agency or group.
radiometerinsuitableradiometricunits,preferablyinwattsper
−2 −1
square metre per volt (Wm V ), and shall be maintained in
5. Apparatus
at least semiannual calibration against a standard source of
5.1 Use exposure racks constructed in accordance with the 9
special irradiance. Narrow band radiometers (for example,
requirements of Practice G7. Unless otherwise specified,
with 20 nm bandpass) can also be used if agreed upon by all
position the exposure racks so that specimens face the equator
interested parties. Narrow band radiometers must also be
and so that the exposed surfaces are 5° from the horizontal. If
calibrated at least semiannually against a standard source of
other exposure rack orientations are used, they must be
spectralirradiance.Acertificateofcalibrationshallbeprovided
reported.
with all total solar-ultraviolet or narrow band irradiance mea-
5.2 Use one of the following rack constructions for expos-
surements. It is recommended that calibrations be traceable to
ing photodegradable plastic specimens:
a recognized national standards agency such as the National
5.2.1 Exposure Rack A—Positionable mounting bars used
Institute for Science and Technology in the United States.
for attaching specimens shall be arrayed over a regular mesh
NOTE 5—The use of narrow band filter UV
...
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