ASTM D6954-04(2013)
(Guide)Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation
Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation
SIGNIFICANCE AND USE
5.1 This guide is a sequential assembly of extant but unconnected standard tests and practices for the oxidation and biodegradation of plastics, which will permit the comparison and ranking of the overall rate of environmental degradation of plastics that require thermal or photooxidation to initiate degradation. Each degradation stage is independently evaluated to allow a combined evaluation of a polymer’s environmental performance under a controlled laboratory setting. This enables a laboratory assessment of its disposal performance in, soil, compost, landfill, and water and for use in agricultural products such as mulch film without detriment to that particular environment.Note 5—For determining biodegradation rates under composting conditions, Specification D6400 is to be used, including test methods and conditions as specified.
5.2 The correlation of results from this guide to actual disposal environments (for example, agricultural mulch films, composting, or landfill applications) has not been determined, and as such, the results should be used only for comparative and ranking purposes.
5.3 The results of laboratory exposure cannot be directly extrapolated to estimate absolute rate of deterioration by the environment because the acceleration factor is material dependent and can be significantly different for each material and for different formulations of the same material. However, exposure of a similar material of known outdoor performance, a control, at the same time as the test specimens allows comparison of the durability relative to that of the control under the test conditions.
SCOPE
1.1 This guide provides a framework or road map to compare and rank the controlled laboratory rates of degradation and degree of physical property losses of polymers by thermal and photooxidation processes as well as the biodegradation and ecological impacts in defined applications and disposal environments after degradation. Disposal environments range from exposure in soil, landfill, and compost in which thermal oxidation may occur and land cover and agricultural use in which photooxidation may also occur.
1.2 In this guide, established ASTM International standards are used in three tiers for accelerating and measuring the loss in properties and molecular weight by both thermal and photooxidation processes and other abiotic processes (Tier 1), measuring biodegradation (Tier 2), and assessing ecological impact of the products from these processes (Tier 3).
1.3 The Tier 1 conditions selected for thermal oxidation and photooxidation accelerate the degradation likely to occur in a chosen application and disposal environment. The conditions should include a range of humidity or water concentrations based on the application and disposal environment in mind. The measured rate of degradation at typical oxidation temperatures is required to compare and rank the polymers being evaluated in that chosen application to reach a molecular weight that constitutes a demonstrable biodegradable residue (using ASTM International biometer tests for CO2 evolution appropriate to the chosen environment). By way of example, accelerated oxidation data must be obtained at temperatures and humidity ranges typical in that chosen application and disposal environment, for example, in soil (20 to 30°C), landfill (20 to 35°C), and composting facilities (30 to 65°C). For applications in soils, local temperatures and humidity ranges must be considered as they vary widely with geography. At least one temperature must be reasonably close to the end use or disposal temperature, but under no circumstances should this be more than 20°C away from the removed that temperature. It must also be established that the polymer does not undergo a phase change, such as glass transition temperature (Tg) within the temperature range of testing.
1.4 The residues resulting from the oxidations are then exposed to appropriate disposal o...
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Designation: D6954 − 04 (Reapproved 2013)
Standard Guide for
Exposing and Testing Plastics that Degrade in the
Environment by a Combination of Oxidation and
Biodegradation
This standard is issued under the fixed designation D6954; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope (20 to 35°C), and composting facilities (30 to 65°C). For
applications in soils, local temperatures and humidity ranges
1.1 This guide provides a framework or road map to
must be considered as they vary widely with geography. At
compare and rank the controlled laboratory rates of degrada-
least one temperature must be reasonably close to the end use
tion and degree of physical property losses of polymers by
or disposal temperature, but under no circumstances should
thermal and photooxidation processes as well as the biodegra-
this be more than 20°C away from the removed that tempera-
dation and ecological impacts in defined applications and
ture. It must also be established that the polymer does not
disposal environments after degradation. Disposal environ-
undergo a phase change, such as glass transition temperature
ments range from exposure in soil, landfill, and compost in
(Tg) within the temperature range of testing.
which thermal oxidation may occur and land cover and
agricultural use in which photooxidation may also occur. 1.4 The residues resulting from the oxidations are then
exposed to appropriate disposal or use environments in stan-
1.2 In this guide, establishedASTM International standards
dard biometric test methods to measure the rate and degree of
are used in three tiers for accelerating and measuring the loss
biodegradation (Tier 2).
in properties and molecular weight by both thermal and
photooxidation processes and other abiotic processes (Tier 1), 1.5 The data generated under Tier 1 evaluation and the
measuring biodegradation (Tier 2), and assessing ecological determined time for the biodegradation in the chosen environ-
impact of the products from these processes (Tier 3). ment (Tier 2) allow ranking relative to other polymers evalu-
ated under similar environmental conditions with this guide.
1.3 TheTier 1 conditions selected for thermal oxidation and
The degree and time for biodegradation should be consistent
photooxidation accelerate the degradation likely to occur in a
with ASTM International methods, and any residues from the
chosen application and disposal environment. The conditions
intermediate oxidation stage and from biodegradation must be
should include a range of humidity or water concentrations
showntobeenvironmentallybenignandnotpersistent(Tier3).
based on the application and disposal environment in mind.
NOTE 1—The intended use of this guide is for comparison and ranking
The measured rate of degradation at typical oxidation tempera-
of data to aid in the design and development and the reduction of
tures is required to compare and rank the polymers being
environmental impacts of polymers that require no more than 24 months
evaluated in that chosen application to reach a molecular to oxidize and biodegrade in the intended use and disposal options and
create no harmful or persistent residues under the appropriate disposal
weight that constitutes a demonstrable biodegradable residue
conditions (for example, two seasons of crop-growing conditions in soil).
(using ASTM International biometer tests for CO evolution
appropriate to the chosen environment). By way of example, 1.6 Itiscautionedthattheresultsofanylaboratoryexposure
in this guide cannot be directly extrapolated to actual disposal
accelerated oxidation data must be obtained at temperatures
and humidity ranges typical in that chosen application and environments; confirmation to real world exposure is ulti-
mately required as with all ASTM International standards.
disposalenvironment,forexample,insoil(20to30°C),landfill
1.7 The values stated in SI units are to be regarded as
standard.
This guide is under the jurisdiction of ASTM Committee D20 on Plastics and
isthedirectresponsibilityofSubcommitteeD20.96onEnvironmentallyDegradable
NOTE2—ThereisnoISOstandardthatistheequivalentofthisstandard
Plastics and Biobased Products.
guide. Note this changed all subsequent Note numbers.
Current edition approved Jan. 1, 2013. Published January 2013. Originally
1.8 This standard does not purport to address all of the
approved in 2004. Last previous edition approved in 2004 as D6954 - 04. DOI:
10.1520/D6954-04R13. safety concerns, if any, associated with its use. It is the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6954 − 04 (2013)
responsibility of the user of this standard to establish appro- 3. Terminology
priate safety and health practices and determine the applica-
3.1 Definitions:
bility of regulatory requirements prior to use.
3.1.1 Definitions of most terms applicable to this guide
appear in Terminology D883 and Guide D6002.
2. Referenced Documents
3.2 Definitions of Terms Specific to This Standard:
2.1 ASTM Standards:
3.2.1 environmental degradation of a plastic, n—abiotic or
D883 Terminology Relating to Plastics
biotic degradation process or both that occurs in a given
D3826 Practice for Determining Degradation End Point in
environment and includes photodegradation, oxidation,
Degradable Polyethylene and Polypropylene Using a Ten-
hydrolysis, and biodegradation. Living organisms effect biotic
sile Test
degradation processes and abiotic degradation processes are
D3987 Practice for Shake Extraction of Solid Waste with
nonbiological in nature.
Water
3.2.1.1 Discussion—Term not defined in Terminology
D5071 Practice for Exposure of Photodegradable Plastics in
D883.
a Xenon Arc Apparatus
3.2.2 gels, n—cross-linked polymer structures insoluble in
D5208 Practice for Fluorescent Ultraviolet (UV) Exposure
solventsthatdonotbreaktheprimaryorcross-linkingbondsin
of Photodegradable Plastics
the polymer. Cross-links created during oxobiodegradadation
D5272 Practice for Outdoor Exposure Testing of Photode-
of polymers are chemical bonds created by the degradation
gradable Plastics
process, mostly carbon-carbon bonds, and thus extremely
D5338 Test Method for Determining Aerobic Biodegrada-
resistant to solvent degradation.
tion of Plastic Materials Under Controlled Composting
3.2.3 oxidation, n—process promoted thermally or by irra-
Conditions, Incorporating Thermophilic Temperatures
diation in the presence of oxygen.
D5510 Practice for Heat Aging of Oxidatively Degradable
Plastics (Withdrawn 2010)
4. Summary of Guide
D5526 Test Method for DeterminingAnaerobic Biodegrada-
tion of Plastic Materials Under Accelerated Landfill Con-
4.1 This guide may be used to compare and rank the rate
ditions
and degree of thermal oxidative degradation of a plastic
D5951 Practice for Preparing Residual Solids Obtained Af- material relatively to a molecular weight range that can be
ter Biodegradability Standard Methods for Plastics in
established as biodegradable in a chosen environment.
Solid Waste for Toxicity and Compost Quality Testing Subsequently, the biodegradation of these degraded polymers
(Withdrawn 2011)
in diverse environments such as soil, compost, landfill, and
D5988 Test Method for Determining Aerobic Biodegrada- water may be compared and ranked using standard biometric
tion of Plastic Materials in Soil
test methods and measuring carbon dioxide evolution.
NOTE 3—If composting is the designated disposal route, Specification
D6002 Guide for Assessing the Compostability of Environ-
D6400 is the only ultimate and definitive applicable specification for
mentally Degradable Plastics (Withdrawn 2011)
measuring biodegradation or compostability. Oxidation followed by
D6400 Specification for Labeling of Plastics Designed to be
biodegradation under the conditions found in this guide does not confer
Aerobically Composted in Municipal or Industrial Facili-
thedesignation“compostable”oranyconnotationthattheapplicationsare
ties
acceptable for composting in a commercial or municipal composting
facility.
E1440 Guide for Acute Toxicity Test with the Rotifer Bra-
chionus
4.2 This guide uses a tiered criteria-based approach to
assesstheconsecutiveoxidationandbiodegradabilityofplastic
2.2 Other Standards:
productsandecologicalimpactsindefinedapplications.Thisis
EPA TITLE 40 CFA 40CFR62, 40CFR50-189, 40CFR260-
shown schematically in Section 6. Each tier in this guide
299, 40CFR300-399, 700-799, and 49CFR100-180
includes objectives and a summary that presents test methods,
OECD Guideline 207 Earthworm, Acute Toxicity Tests
method principles, test duration, and interpretation of results.
OECD Guideline 208 Terrestrial Plants, Growth Test
ORCA Guidelines for the Evaluation of Feedstock for
4.3 The tiered approach is chosen in the laboratory for
Source Separated Biowaste Composting and Biogasifica-
convenient separation of oxidative degradation,
tion
biodegradation, and ecological impact stages even though in
the real world all three are likely to be concurrent rather than
consecutive.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.4 Tiered Methodology:
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.4.1 Tier 1 measures the rate and extent of molecular
Standards volume information, refer to the standard’s Document Summary page on
weight loss resulting from oxidation that is indicative of losses
the ASTM website.
The last approved version of this historical standard is referenced on
in physical properties from oxidation. Tier 1 requires either
www.astm.org.
accelerated testing or long-term testing over a range of relative
Available from United States Environmental Protection Association (EPA),
Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460.
Available from OECD, 2 rue Andre Pascal, F-75775 Paris Cedex 16, France.
6 7
Available from ORCA, Avenue E. Mounier 83, Box 1, Brussels, Belgium Vollmert, B., Polymer Chemistry, Springer-Verlag, NewYork, 1973, p. 27, also
B-1200. pp. 543- 561.
D6954 − 04 (2013)
humidity or amount of moisture. Accelerated testing must be 5. Significance and Use
performed under conditions and temperatures that are accept-
5.1 This guide is a sequential assembly of extant but
ably typical of the specific application and disposal environ-
unconnected standard tests and practices for the oxidation and
ments under consideration. Practices D5208, D5510, and
biodegradation of plastics, which will permit the comparison
D5071 may be used to specify the oxidative conditions and
and ranking of the overall rate of environmental degradation of
Practice D3826 may be used to define the point of embrittle-
plastics that require thermal or photooxidation to initiate
ment.
degradation. Each degradation stage is independently evalu-
ated to allow a combined evaluation of a polymer’s environ-
NOTE 4—For measuring the extent of disintegration/fragmentation, a
mental performance under a controlled laboratory setting. This
sieve test is required. In this tier, the fragments are subjected to molecular
enables a laboratory assessment of its disposal performance in,
weight analysis and a total mass balance is obtained in the process.
Exposure temperatures may range from 20 to 70°C in the presence of air
soil, compost, landfill, and water and for use in agricultural
andspecifiedmoistureorwaterlevelsforselectedperiodsoftime.Atleast
productssuchasmulchfilmwithoutdetrimenttothatparticular
one temperature must be reasonably close to the end use or disposal
environment.
temperature, but under no circumstances should this be more than 20°C
NOTE 5—For determining biodegradation rates under composting
away from that temperature. It must also be established that the polymer
conditions, Specification D6400 is to be used, including test methods and
doesnotundergoaphasechange,suchasglasstransitiontemperature(Tg)
conditions as specified.
within the temperature range of testing. As an alternate degradation
5.2 The correlation of results from this guide to actual
process, the test samples may be exposed to photooxidation in air as per
Practices D5208 or D5071 and the mass change of the plastic recorded
disposal environments (for example, agricultural mulch films,
after exposure.
composting, or landfill applications) has not been determined,
and as such, the results should be used only for comparative
4.4.2 Tier 1 accelerated oxidation tests are not indicators of
and ranking purposes.
biodegradability and should not be used for the purpose of
meeting the specifications as described in Specification D6400
5.3 The results of laboratory exposure cannot be directly
and claiming compostability or biodegradation during com-
extrapolated to estimate absolute rate of deterioration by the
posting. (If oxidation is thought to be sufficiently rapid in Tier
environment because the acceleration factor is material depen-
1, suggesting that composting may be a disposal environment,
dent and can be significantly different for each material and for
then Specification D6400 must be done and all the specifica- differentformulationsofthesamematerial.However,exposure
of a similar material of known outdoor performance, a control,
tions in Section 6 (Detailed Requirements) must be met.
atthesametimeasthetestspecimensallowscomparisonofthe
4.5 Gel Formation and Consequences During Oxidation
durability relative to that of the control under the test condi-
Phase—Discussion:
tions.
4.5.1 Gel formation is a frequent side reaction of the
6. Procedures
oxidativedegradationofpolymers,especiallypolyolefins.Gels
are cross-linked structures arising from the free radical nature 6.1 Test sample selected to be in the thickness of the
of oxidative degradation. They are insoluble in nonreactive application form.
solvents, that is, solvents that do not break additional bonds.
6.2 The tier testing procedure is outlined schematically in
Normally, gels are not available to biodegradation. Some gels
Fig. 1.
dissolveonfurtheroxidativedegradationandbecomeavailable
6.3 In Tier 1, the test sample is exposed to several discrete
forultimatebiodegradation.However,theprooxidant(catalyst)
temperatures (one being within 20°C of the end use tempera-
may be excluded from the gel structure because of solubility
ture)withintherangeof20to70°Cinthepresenceofspecified
changes in gel phase. In this case, the gel would become a
levels of air and specified moisture or water levels for defined
nondegradable or very s
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