ASTM D3826-98(2002)
(Practice)Standard Practice for Determining Degradation End Point in Degradable Polyethylene and Polypropylene Using a Tensile Test
Standard Practice for Determining Degradation End Point in Degradable Polyethylene and Polypropylene Using a Tensile Test
SIGNIFICANCE AND USE
The tensile elongation property determined by this practice is of value for the characterization of degradable materials. The tensile elongation property may vary with specimen thickness, method of preparation, speed of testing, type of grips used, and manner of measuring test extension. Consequently, where precise comparative results are desired, these factors must be carefully controlled.
The tensile elongation property may be utilized to provide data for research and development and engineering design as well as quality control specifications. However, data from such tests cannot be considered significant for applications differing widely from the load-time scale of the test employed.
Materials that fail by tearing give anomalous data that cannot be compared with those from normal failure.
Before proceeding with this test method, reference should be made to the specifications of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters or a combination thereof, covered in the material specifications shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.
SCOPE
1.1 This practice covers the determination of a degradation-end point (a brittle point) for degradable polyethylene/polypropylene films and sheeting less than 1.0 mm (0.04 in.) thick. This practice is not intended for determination of the rate of degree of degradation of a polyethylene/polypropylene film or sheet, but rather, to assess when in the course of its degradation under some condition, a brittle point is reached. If one wishes to monitor tensile elongation during the degradation process (such as when the tensile elongation is significantly greater than 5 %), Test Method D 882 is recommended. This practice should not be considered the only way of determining a degradation-end point.
1.2 Tensile properties of plastics 1.0 mm (0.04 in.) or greater in thickness shall be determined in accordance with Test Method D 638.
1.3 Use a static weighing-constant rate of grip separation test. This procedure employs a constant rate of separation of the grips holding the sample and a static load cell.
Note 1—This procedure is based on the use of grip separation as a measure of extension; however, the desirability of using extension indicators accurate to ±1.0 % or better as specified in Test Method D 638 is recognized, and a provision for the use of such instrumentation is incorporated in the procedure.
1.4 This procedure has been successful for determining the degradation end point of ethylene-carbon-monoxide copolymers and has screened successfully two other additive-type polyethylenes in a round robin test.
1.5 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.6 This standard does not purport to address all of the safety concerns, 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.
1.7 There is no equivalent ISO standard.
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Designation:D 3826–98 (Reapproved 2002)
Standard Practice for
Determining Degradation End Point in Degradable
Polyethylene and Polypropylene Using a Tensile Test
This standard is issued under the fixed designation D 3826; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 There is no equivalent ISO standard.
1.1 This practice covers the determination of a degradation-
2. Referenced Documents
end point (a brittle point) for degradable polyethylene/
2.1 ASTM Standards:
polypropylene films and sheeting less than 1.0 mm (0.04 in.)
D 374 Test Methods for Thickness of Solid Electrical Insu-
thick.This practice is not intended for determination of the rate
lation
of degree of degradation of a polyethylene/polypropylene film
D 618 Practice for Conditioning Plastics and Electric Insu-
or sheet, but rather, to assess when in the course of its
lating Materials for Testing
degradation under some condition, a brittle point is reached. If
D 638M Test Method for Tensile Properties of Plastics
one wishes to monitor tensile elongation during the degrada-
[Metric]
tion process (such as when the tensile elongation is signifi-
D 882 Test Methods for Tensile Properties of Thin Plastic
cantly greater than 5 %), Test Method D 882 is recommended.
Sheeting
This practice should not be considered the only way of
D 5208 PracticeforOperatingFluorescentUVandConden-
determining a degradation-end point.
sation Apparatus for Exposure of Photodegradable Plas-
1.2 Tensile properties of plastics 1.0 mm (0.04 in.) or
tics
greater in thickness shall be determined in accordance with
E 691 Practice for Conducting an Interlaboratory Study to
Test Method D 638.
Determine the Precision of a Test Method
1.3 Use a static weighing-constant rate of grip separation
test. This procedure employs a constant rate of separation of
3. Terminology
the grips holding the sample and a static load cell.
3.1 Definitions:
NOTE 1—This procedure is based on the use of grip separation as a
3.1.1 Definitions of terms and symbols relating to tension
measure of extension; however, the desirability of using extension
testing of plastics appear in the Annex to Test Method D 638.
indicators accurate to 61.0 % or better as specified in Test Method D 638
3.1.2 line grips, n—in tensile testing machines, grips having
is recognized, and a provision for the use of such instrumentation is
faces designed to concentrate the entire gripping force along a
incorporated in the procedure.
single line perpendicular to the direction of testing stress.
1.4 This procedure has been successful for determining the
3.1.3 tear failure, n—in tensile testing of films, a failure
degradation end point of ethylene-carbon-monoxide copoly-
characterized by fracture initiating at one edge of the specimen
mers and has screened successfully two other additive-type
and progressing across the specimen at a rate slow enough to
polyethylenes in a round robin test.
produce an anomalous load-deformation curve.
1.5 The values stated in SI units are to be regarded as the
3.2 Description of Terms Specific to This Standard:
standard. The values in parentheses are for information only.
3.2.1 film, n—for the purpose of this practice, a piece of
1.6 This standard does not purport to address all of the
material not exceeding 0.250 mm (0.01 in.) in thickness.
safety concerns, if any, associated with its use. It is the
3.2.2 brittle point, n—in degradable polyethylene/
responsibility of the user of this standard to establish appro-
polypropylene film, that point in the history of a material when
priate safety and health practices and determine the applica-
75 % of the specimens tested have a tensile elongation at break
bility of regulatory limitations prior to use.
of 5 % or less.
This practice is under the jurisdiction ofASTM Committee D20 on Plastics and
isthedirectresponsibilityofSubcommitteeD20.96onEnvironmentallyDegradable Annual Book of ASTM Standards, Vol 10.01.
Plastics. Annual Book of ASTM Standards, Vol 08.01.
Current edition approved April 10, 1998. Published January 1999. Originally Annual Book of ASTM Standards, Vol 08.03.
e1 5
published as D 3826 – 91. Last previous edition D 3826 – 91 . Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3826–98 (2002)
4. Significance and Use consisting of two parallel knives mounted firmly against a
precision-ground base shear-block (similar to a paper cutter)
4.1 The tensile elongation property determined by this
has proved satisfactory. The use of striking dies is not
practice is of value for the characterization of degradable
recommended because poor and inconsistent specimen edges
materials. The tensile elongation property may vary with
may be produced. It is imperative that the cutting edges be kept
specimen thickness, method of preparation, speed of testing,
sharp and free from visible scratches or nicks.
type of grips used, and manner of measuring test extension.
5.6 Extension Indicators—If employed, extension indica-
Consequently, where precise comparative results are desired,
tors shall conform to requirements specified in Test Method D
these factors must be carefully controlled.
638. In addition, such apparatus shall be so designed as to
4.2 The tensile elongation property may be utilized to
minimize stress on the specimen at the contact points of the
provide data for research and development and engineering
specimen and the indicator.
design as well as quality control specifications. However, data
from such tests cannot be considered significant for applica-
NOTE 3—A high-response speed in the recording system is desirable,
tions differing widely from the load-time scale of the test
particularly when relatively high strain rates are employed for rigid
materials. The speed of pen response for recorders is supplied by
employed.
manufacturers of this equipment. Take care to conduct tests at conditions
4.3 Materials that fail by tearing give anomalous data that
suchthatresponsetime(abilityofrecordertofollowactualload)produces
cannot be compared with those from normal failure.
less than 2 % error.
4.4 Before proceeding with this test method, reference
should be made to the specifications of the material being
6. Test Specimen
tested. Any test specimen preparation, conditioning, dimen-
6.1 Cut test specimens prior to exposure. Take utmost care
sions, or testing parameters or a combination thereof, covered
in cutting specimens to prevent nicks and tears that are likely
in the material specifications shall take precedence over those
to cause premature failures (see Note 4). The edges shall be
mentioned in this test method. If there are no material
parallel to within 5 % of the width over the length of the
specifications, then the default conditions apply.
specimen between the grips.
5. Apparatus
NOTE 4—A microscopic examination of the specimen may be used to
detect flaws due to sample or specimen preparation.
5.1 Testing Machines:
5.1.1 Use a testing machine of the constant rate-of-jaw- 6.2 Prepare the test specimen with uniform width and
separation type. The machine shall be equipped with a weigh-
length. Examples of typical lengths and widths are:
ing system that moves a maximum distance of 2 % of the
Width, mm Length, mm
13 (0.5 in.) 152 (6 in.)
specimen extension within the range being measured. Also,
25 (1.0 in.) 102 (4 in.)
there should be a device for recording the tensile load and the
amount of separation of the grips; both of these measuring
6.2.1 The test specimen thickness is contingent upon the
systems shall be accurate to 62 %. The rate of separation of
thickness of the end-use application. The test specimen thick-
the grips shall be uniform and capable of adjustment from
ness should be the same as that for the specific end-use
approximately 1.3 to 500 mm/min (0.05 to 20 in./min) in
application.
increments necessary to produce the strain rates specified in
6.3 Wherever possible, select test specimen so that thick-
9.2.
ness is uniform to within 10 % of the thickness over the
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