ASTM D2561-95(2005)
(Test Method)Standard Test Method for Environmental Stress-Crack Resistance of Blow-Molded Polyethylene Containers
Standard Test Method for Environmental Stress-Crack Resistance of Blow-Molded Polyethylene Containers
SIGNIFICANCE AND USE
When properly used, these procedures may serve to isolate such factors as material, blow-molding conditions, post-treatment, and so forth, on the stress-crack resistance of the container.
Environmental stress cracking of blow-molded containers is governed by many factors. Since variance of any of these factors can change the environmental stress-crack resistance of the container, the test results are representative only of a given test performed under defined conditions in the laboratory. The reproducibility of results between laboratories on containers made on more than one machine from more than one mold has not been established.
Results can be used for estimating the shelf life of blow-molded containers in terms of their resistance to environmental stress cracking provided this is done against a rigorous background of practical field experience and reproducible test data.
Before proceeding with this test method, reference should be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.
SCOPE
1.1 Under certain conditions of stress, and in the presence of environments such as soaps, wetting agents, oils, or detergents, blow-molded polyethylene containers may exhibit mechanical failure by cracking at stresses appreciably below those that would cause cracking in the absence of these environments.
1.2 This test method measures the environmental stress- crack resistance of containers, which is the summation of the influence of container design, resin, blow-molding conditions, post treatment, or other factors that can affect this property. Three procedures are provided as follows:
1.2.1 Procedure A, Stress-Crack Resistance of Containers to Commercial Liquids—This procedure is particularly useful for determining the effect of container design on stress-crack resistance or the stress-crack resistance of a proposed commercial package containing a proprietary liquid product.
1.2.2 Procedure B, Stress-Crack Resistance of a Specific Container to Polyoxyethylated Nonylphenol, a Stress-Cracking Agent—The conditions of test described in this procedure are designed for testing containers made from Type III polyethylene Specification D1248. Therefore, this procedure is recommended for containers made from Type III polyethylene only. This procedure is particularly useful for determining the effect of resin on the stress-crack resistance of the container.
1.2.3 Procedure C, Controlled Elevated Pressure Stress-Crack Resistance of a Specific Container to Polyoxyethylated Nonylphenol, a Stress-Cracking Agent—The internal pressure is controlled at a constant elevated level.
1.3 These procedures are not designed to test the propensity for environmental stress cracking in the neck of containers, such as when the neck is subjected to a controlled strain by inserting a plug.
1.4 The values stated in SI units are to be regarded as the standard.
Note 1—There is no similar or equivalent ISO standard.
1.5 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. Specific precautionary statements are given in Section 8 and Notes 1 and 9.
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Standards Content (Sample)
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Designation: D2561 − 95(Reapproved 2005)
Standard Test Method for
Environmental Stress-Crack Resistance of Blow-Molded
Polyethylene Containers
This standard is issued under the fixed designation D2561; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.4 The values stated in SI units are to be regarded as
standard.
1.1 Undercertainconditionsofstress,andinthepresenceof
environmentssuchassoaps,wettingagents,oils,ordetergents,
NOTE 1—There is no known ISO equivalent to this standard.
blow-molded polyethylene containers may exhibit mechanical
1.5 This standard does not purport to address all of the
failure by cracking at stresses appreciably below those that
safety concerns, if any, associated with its use. It is the
would cause cracking in the absence of these environments.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.2 This test method measures the environmental stress
bility of regulatory limitations prior to use. Specific precau-
crack resistance of containers, which is the summation of the
tionary statements are given in Section 8 and Note 1 and Note
influence of container design, resin, blow-molding conditions,
8.
post treatment, or other factors that can affect this property.
Three procedures are provided as follows:
2. Referenced Documents
1.2.1 Procedure A, Stress-Crack Resistance of Containers to
Commercial Liquids—This procedure is particularly useful for
2.1 ASTM Standards:
determining the effect of container design on stress-crack
D374Test Methods for Thickness of Solid Electrical Insu-
resistanceorthestress-crackresistanceofaproposedcommer-
lation
cial package containing a proprietary liquid product.
D618Practice for Conditioning Plastics for Testing
1.2.2 Procedure B, Stress-Crack Resistance of a Specific
D4976Specification for Polyethylene Plastics Molding and
Container to Polyoxyethylated Nonylphenol, a Stress-Cracking
Extrusion Materials
Agent—The conditions of test described in this procedure are
E145Specification for Gravity-Convection and Forced-
designedfortestingcontainersmadefromClass3polyethylene
Ventilation Ovens
Specification D4976. Therefore, this procedure is recom-
mended for containers made from Class 3 polyethylene only.
3. Terminology
This procedure is particularly useful for determining the effect
3.1 Definitions of Terms Specific to This Standard:
of resin on the stress-crack resistance of the container.
3.2 failure—during this test method, the formation of any
1.2.3 Procedure C, Controlled Elevated Pressure Stress-
imperfection, such as a crack, which results in a loss of
Crack Resistance of a Specific Container to Polyoxyethylated
pressurizinggasorstress-crackingagent.Acontainerhasfailed
Nonylphenol, a Stress-Cracking Agent—The internal pressure
when:
is controlled at a constant elevated level.
3.2.1 It has lost pressure through any aperture other than
1.3 Theseproceduresarenotdesignedtotestthepropensity
heat seal areas; or, in Procedure C, when there is a detectable
for environmental stress cracking in the neck of containers,
flow of supply air into the bottle,
such as when the neck is subjected to a controlled strain by
3.2.2 There is visible to an observer with normal eyesight
inserting a plug.
any crack completely through the container wall, or
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
and is the direct responsibility of Subcommittee D20.19 on Film, Sheeting, and
Molded Products. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 15, 2005. Published August 2005. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1966. Last previous edition approved in 2001 as D2561-95 (2001). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D2561-95R05. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2561 − 95 (2005)
3.2.3 There is evidence of the contained liquid on the 6.1.1 Circulating-Air Oven, consistent with ovens pre-
outside of the container through any aperture other than one at scribed in Specification E145, except for size, capable of
the heat-seal area, or the contained liquid volume has been maintaining a temperature of 60 6 1°C (140 6 1.8°F) and an
3 3
reduced. airflow rate of 8.5 to 17 m /min (300 to 600 ft /min).
(Warning— A high-temperature safety switch is highly rec-
4. Summary of Test Method ommended on this oven. Some test liquids can cause extreme
pressure buildup upon heating. Under these conditions bottles
4.1 Procedure A consists of exposing any filled, sealed,
can rupture with explosive force. This condition can cause
blow-molded container to the action of a potential stress-
injury to the operator as well as damage to the ovens. The
crackingagentwithinthecontainer,atanelevatedtemperature.
override cutoff switch should be set to turn off the oven heat if
The time to failure is observed.
the test temperature is exceeded by as much as 10°C (18°F). )
4.2 Procedure B consists of exposing a partly filled and
6.1.2 Balance, accurate to within 61.0 g (for weighing
sealed blow-molded standard container to the action of poly-
containers and contents) or a volumetric filling apparatus
oxyethylated nonylphenol, a stress-cracking agent, within the
accurate to 61 mL.
container, as well as to the action of this agent as an external
6.2 For Procedures A and B Only:
environment, at an elevated temperature. The time to failure is
6.2.1 Heat-Seal Laminate for sealing the containers.
observed.
5,6
6.2.2 Heat-Sealing Unit.
7,6
4.3 Procedure C consists of exposing a partly filled blow-
6.2.3 Torque Meter.
molded standard container to the action of polyoxyethylated
6.2.4 Glass Beakers, large enough to hold the contents of
nonylphenol, a stress-cracking agent, within the container, as
one test container.
wellastoaconstantelevatedpressureinternallyappliedandat
6.3 For Procedures A and C Only:
anelevatedtemperature.Thetime-to-failurecanbedetermined
6.3.1 Polyethylene Bags, approximately 0.038-mm (1.5-
in a tactual-visual manner, or instrumentally.
mil) thick, large enough to enclose completely a test container.
The bag should fit loosely around the container and be long
5. Significance and Use
enough so that the bag opening can be closed above the
5.1 When properly used, these procedures may serve to
container closure.
isolate such factors as material, blow-molding conditions,
6.4 For Procedure C Only:
post-treatment, and so forth, on the stress-crack resistance of
6.4.1 The essential parts of this apparatus are schematically
the container.
showninFig.1.Additionalrefinementsinfaildetectioncanbe
5.2 Environmental stress cracking of blow-molded contain-
added as shown in Fig. 2. The necessary equipment is as
ersisgovernedbymanyfactors.Sincevarianceofanyofthese
follows:
factorscanchangetheenvironmentalstress-crackresistanceof
6.4.1.1 Clear Air Supply of sufficient pressure to operate
the container, the test results are representative only of a given
regulator and maintain regulated pressure to manifold.
test performed under defined conditions in the laboratory. The
6.4.1.2 Air Filter, to remove oil, water, dust, and other
reproducibility of results between laboratories on containers
contaminants.
made on more than one machine from more than one mold has
6.4.1.3 Pressure Regulator, to reduce line pressure to 34.5
not been established.
6 1.72 kPa (5.0 6 0.25 psig).
6.4.1.4 Pressure Gages, calibrated to indicate a pressure of
5.3 Results can be used for estimating the shelf life of
34.5 kPa (5.0 psig) with a precision of 0.34 kPa (0.05 psig).
blow-molded containers in terms of their resistance to envi-
ronmental stress cracking provided this is done against a
NOTE 2—Amercury manometer is of benefit in calibrating the pressure
rigorous background of practical field experience and repro-
gages, and monitoring precise pressure measurements.
ducible test data.
6.4.1.5 Air Valves.
5.4 Before proceeding with this test method, reference
6.4.1.6 Restricting Line Orifice or Needle Valve—This re-
shouldbemadetothespecificationofthematerialbeingtested.
striction retards the flow of air to the bottle so that supply
Any test specimen preparation, conditioning, dimensions, or
pressure remains constant after bottle failure, enabling a
testing parameters, or a combination thereof, covered in the
number of bottles to be pressurized from a single regulated
materials specification shall take precedence over those men-
supply.Pressuredroponthebottlesideofthisrestrictionisone
tioned in this test method. If there are no material specifica-
tions, then the default conditions apply.
The sole source of supply of the polyethylene-foil laminate (aluminum seal)
6. Apparatus known to the committee at this time is Berlin Packaging, 111 North Canal St., Suite
300, Chicago, IL 60606.
6.1 For Procedures A, B, and C: 5
The sole source of supply of the Selector Hand Sealing Iron (165W) known to
the committee at this time is Selector of Shelton, CT.
If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider-
3 1
The sole source of supply of the Igepal CO-630 (Antarox CO-630) known to ation at a meeting of the responsible technical committee, which you may attend.
thecommitteeatthistimeisGAFCorp.,DyestuffandChemicalDiv.,140W.51St., ThesolesourceofsupplyoftheModel25Owens-IllinoisSpringTorqueTester
New York, NY 10020. known to the committee at this time is Owens-Illinois Glass Co., Toledo, OH.
D2561 − 95 (2005)
FIG. 1 Apparatus for Procedure C
FIG. 2 Apparatus for Procedure C, Including Refinements in Failure Detection
NOTE 5—Since only about 0.1 mL(2 drops) of this solution is added to
indication of bottle failure. The orifice size or restriction used
each bottle, only a small volume is needed.
willdependuponthesensitivityofthepressureswitchorgage.
Orifices that pass 300 cm /min at 6.9 kPa (1 psi) differential 7.3 For Procedure C:
pressure have been found satisfactory. Needle valves, which 7.3.1 Polyoxyethylated Nonylphenol, a stress-cracking
3 3
may be adjusted to flow rates as low as 5.0 cm /min, may be agent. See Note 3.
useful in cases where greater sensitivity to small failures is 7.3.2 Polyoxyethylated Nonylphenol Solution—Prepare a
desired. 33 ⁄3 % solution by volume, of the stress-cracking agent in
6.4.1.7 Bottle Cap Assemblies—Each bottle must be se- distilled water in sufficient volume to fill a minimum of fifteen
curely sealed and attached to the test fixture. Assemblies 473-mL (16-oz) containers to one fourth of the overflow
essentially like those shown in Fig. 3 have been found capacity (133 mL). See Note 4.
satisfactory.
8. Safety Precautions
7. Reagents 8.1 Proper precautions should be taken to prevent overheat-
ing of the containers during testing since some products which
7.1 For Procedure A—Anyreagentorproprietaryliquidthat
may be tested by ProcedureAmay cause an extreme pressure
is potentially an environmental stress-cracking agent.
buildup in the container and could cause the container to
7.2 For Procedure B:
rupture explosively. Proper safety measures against over-
7.2.1 Polyoxyethylated Nonylphenol, a stress-cracking
heating are described in the warning note at the end of 6.1.1.
agent.
8.2 Sometimes a container will fail by means of a small
NOTE 3—Polyoxyethylated nonylphenol is hygroscopic and the undi-
pinhole. Since the container is under pressure during the test,
luted agent should be kept tightly stoppered.
liquid may be forced out of the opening spraying the inside of
7.2.2 Polyoxyethylated Nonylphenol Solution—Prepare a
the oven and the operator, if an inspection is being made.
10% solution, by volume, of the stress-cracking agent in
Precautions to prevent this from happening are described in
distilled water in sufficient volume to fill a minimum of fifteen
11.1.4.
473-mL (16-oz) containers to one third of overflow capacity
8.3 Care should be taken in handling the stress-cracking
(178 mL).
agent since there is some possibility of its causing dermatitis.
NOTE 4—It has been found to be helpful due to the viscosity of the
8.4 Proper precautions should be taken in handling com-
stress-cracking agent, to prepare the solution at an elevated temperature.
pressed air equipment when following Procedure C.
A temperature of 50°C (120°F) has been found suitable.
7.2.3 Dye Indicator Solution—Add 0.1% by weight of a 9. Test Specimen
wetting agent to distilled water. Dissolve 0.001% by weight
9.1 For Procedure A—A minimum of 15 blow-molded
of Gentian Violet in the water.
containers,representativeofthelottobetested,andfittedwith
a screw closure affording a leakproof seal, shall be selected.
9.2 For Procedures B and C—A standard blow-molded
The sole source of supply of theAerosol OT Solution known to the committee
at this time is Fisher Scientific Corp., 203 Fisher Building, Pittsburgh, PA 15219. container shall be used for this test. It is a 473-mL (16-oz)
D2561 − 95 (2005)
FIG. 3 Bottle Pressure Seal and Tube
NOTE 8—The pressure applied during sealing should be a minimum to
cylindrical bottle weighing approximately 20 g, as shown in
ensure no deformation of the container. The container should not be
Fig. 4.Aminimum of 15 containers shall be selected as in 9.1.
handled in such a manner as to deform the walls during sealing. Any
The minimum wall thickness of the container shall be not less
deformationofthecontainerduringsealingmayresultinavolumechange
than 0.305 mm (12 mil). The pinch-off area of the container
which will affect the final test pressure.An application torque of 1.7 N·m
shall not extend into the chime radius. (15 in·lbf) has been found sufficient for the standard container described
in Fig. 4.
NOTE 6—Test Methods D374, modified to use a ball tip micrometer,
11.1.3 After sealing, invert the containers to coat the inside
may be used to measure the thickness of the container.
walls with the agent.
10. Conditioning
11.1.4 Place each container in a plastic bag and close the
bag opening above the closure by folding or by means of a
10.1 Conditioning—Condition the test specimens at 23 6
rubber band, string, tape, etc. Do not heat-seal the bag.
2°C(73.4 63.6°F)and50 65%relativehumidityfornotless
(Warning—Aplastic bag
...
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