ASTM D2561-95(2001)
(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
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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Designation: D 2561 – 95 (Reapproved 2001)
Standard Test Method for
Environmental Stress-Crack Resistance of Blow-Molded
Polyethylene Containers
This standard is issued under the fixed designation D 2561; 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.
NOTE 1—There is no similar or equivalent ISO standard.
1. Scope
1.1 Undercertainconditionsofstress,andinthepresenceof 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
environments such as soaps, wetting agents, oils, or detergents,
blow-molded polyethylene containers may exhibit mechanical responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
failure by cracking at stresses appreciably below those that
would cause cracking in the absence of these environments. bility of regulatory limitations prior to use. Specific precau-
tionary statements are given in Section 8 and Note 1 and Note
1.2 This test method measures the environmental stress
crack resistance of containers, which is the summation of the 9.
influence of container design, resin, blow-molding conditions,
2. Referenced Documents
post treatment, or other factors that can affect this property.
2.1 ASTM Standards:
Three procedures are provided as follows:
D 374 Test Methods for Thickness of Solid Electrical Insu-
1.2.1 ProcedureA, Stress-Crack Resistance of Containers to
lation
Commercial Liquids—This procedure is particularly useful for
D 618 Practice for Conditioning Plastics for Testing
determining the effect of container design on stress-crack
D 1248 Specification for Polyethylene Plastics Extrusion
resistance or the stress-crack resistance of a proposed commer-
Materials for Wire and Cable
cial package containing a proprietary liquid product.
E 145 Specification for Gravity-Convection and Forced-
1.2.2 Procedure B, Stress-Crack Resistance of a Specific
Ventilation Ovens
Container to Polyoxyethylated Nonylphenol, a Stress-Cracking
Agent—The conditions of test described in this procedure are
3. Terminology
designed for testing containers made from Type III polyethyl-
3.1 Definitions of Terms Specific to This Standard:
ene Specification D 1248. Therefore, this procedure is recom-
3.2 failure—during this test method, the formation of any
mended for containers made from Type III polyethylene only.
imperfection, such as a crack, which results in a loss of
This procedure is particularly useful for determining the effect
pressurizinggasorstress-crackingagent.Acontainerhasfailed
of resin on the stress-crack resistance of the container.
when:
1.2.3 Procedure C, Controlled Elevated Pressure Stress-
3.2.1 It has lost pressure through any aperture other than
Crack Resistance of a Specific Container to Polyoxyethylated
heat seal areas; or, in Procedure C, when there is a detectable
Nonylphenol, a Stress-Cracking Agent—The internal pressure
flow of supply air into the bottle,
is controlled at a constant elevated level.
3.2.2 There is visible to an observer with normal eyesight
1.3 These procedures are not designed to test the propensity
any crack completely through the container wall, or
for environmental stress cracking in the neck of containers,
3.2.3 There is evidence of the contained liquid on the
such as when the neck is subjected to a controlled strain by
outside of the container through any aperture other than one at
inserting a plug.
the heat-seal area, or the contained liquid volume has been
1.4 The values stated in SI units are to be regarded as the
reduced.
standard.
1 2
This test method is under the jurisdiction ofASTM Committee D20 on Plastics For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and is the direct responsibility of Subcommittee D20.20 on Plastic Products. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved November 10, 1995. Published January 1996. Origi- Standards volume information, refer to the standard’s Document Summary page on
nally published as D 2561 – 66 T. Last previous edition D 2561 – 91. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 2561 – 95 (2001)
4. Summary of Test Method 5.3 Results can be used for estimating the shelf life of
blow-molded containers in terms of their resistance to envi-
4.1 Procedure A consists of exposing any filled, sealed,
ronmental stress cracking provided this is done against a
blow-molded container to the action of a potential stress-
rigorous background of practical field experience and repro-
crackingagentwithinthecontainer,atanelevatedtemperature.
ducible test data.
The time to failure is observed.
FIG. 1 Apparatus for Procedure C
FIG. 2 Apparatus for Procedure C, Including Refinements in Failure Detection
4.2 Procedure B consists of exposing a partly filled and 5.4 Before proceeding with this test method, reference
sealed blow-molded standard container to the action of poly- shouldbemadetothespecificationofthematerialbeingtested.
oxyethylated nonylphenol, a stress-cracking agent, within the Any test specimen preparation, conditioning, dimensions, or
container, as well as to the action of this agent as an external testing parameters, or a combination thereof, covered in the
environment, at an elevated temperature. The time to failure is materials specification shall take precedence over those men-
observed. tioned in this test method. If there are no material specifica-
4.3 Procedure C consists of exposing a partly filled blow- tions, then the default conditions apply.
molded standard container to the action of polyoxyethylated
nonylphenol, a stress-cracking agent, within the container, as
6. Apparatus
well as to a constant elevated pressure internally applied and at
6.1 For Procedures A, B, and C:
an elevated temperature.The time-to-failure can be determined
6.1.1 Circulating-Air Oven, consistent with ovens pre-
in a tactual-visual manner, or instrumentally.
scribed in Specification E 145, except for size, capable of
maintaining a temperature of 60 6 1°C (140 6 1.8°F) and an
3 3
5. Significance and Use
airflow rate of 8.5 to 17 m /min (300 to 600 ft /min).
5.1 When properly used, these procedures may serve to
NOTE 2—Caution: A high-temperature safety switch is highly recom-
isolate such factors as material, blow-molding conditions,
mended on this oven. Some test liquids can cause extreme pressure
post-treatment, etc., on the stress-crack resistance of the
buildup upon heating. Under these conditions bottles can rupture with
container.
explosive force. This condition can cause injury to the operator as well as
damage to the ovens. The override cutoff switch should be set to turn off
5.2 Environmental stress cracking of blow-molded contain-
the oven heat if the test temperature is exceeded by as much as 10°C
ers is governed by many factors. Since variance of any of these
(18°F).
factors can change the environmental stress-crack resistance of
the container, the test results are representative only of a given 6.1.2 Balance, accurate to within 61.0 g (for weighing
test performed under defined conditions in the laboratory. The containers and contents) or a volumetric filling apparatus
reproducibility of results between laboratories on containers accurate to 61 mL.
made on more than one machine from more than one mold has 6.2 For Procedures A and B Only:
not been established. 6.2.1 Heat-Seal Laminate for sealing the containers.
3 4
Igepal CO-630 (Antarox CO-630) obtained from GAF Corp., Dyestuff and Asuitable polyethylene-foil laminate (aluminum seal) is available from Berlin
Chemical Div., 140 W. 51 St., New York, NY 10020. Packaging, 111 North Canal St., Suite 300, Chicago, IL 60606.
D 2561 – 95 (2001)
6.2.2 Heat-Sealing Unit. 6.4.1.6 Restricting Line Orifice or Needle Valve—This re-
6.2.3 Torque Meter. striction retards the flow of air to the bottle so that supply
6.2.4 Glass Beakers, large enough to hold the contents of pressure remains constant after bottle failure, enabling a
one test container. number of bottles to be pressurized from a single regulated
6.3 For Procedures A and C Only: supply.Pressuredroponthebottlesideofthisrestrictionisone
6.3.1 Polyethylene Bags, approximately 0.038-mm (1.5- indication of bottle failure. The orifice size or restriction used
mil) thick, large enough to enclose completely a test container. will depend upon the sensitivity of the pressure switch or gage.
The bag should fit loosely around the container and be long Orifices that pass 300 cm /min at 6.9 kPa (1 psi) differential
enough so that the bag opening can be closed above the pressure have been found satisfactory. Needle valves, which
container closure. may be adjusted to flow rates as low as 5.0 cm /min, may be
6.4 For Procedure C Only: useful in cases where greater sensitivity to small failures is
6.4.1 The essential parts of this apparatus are schematically desired.
shown in Fig. 1.Additional refinements in fail detection can be 6.4.1.7 Bottle Cap Assemblies—Each bottle must be se-
added as shown in Fig. 2. The necessary equipment is as curely sealed and attached to the test fixture. Assemblies
follows: essentially like those shown in Fig. 3 have been found
FIG. 3 Bottle Pressure Seal and Tube
6.4.1.1 Clear Air Supply of sufficient pressure to operate satisfactory.
regulator and maintain regulated pressure to manifold.
6.4.1.2 Air Filter, to remove oil, water, dust, and other 7. Reagents
contaminants.
7.1 For Procedure A—Any reagent or proprietary liquid
6.4.1.3 Pressure Regulator, to reduce line pressure to 34.5
that is potentially an environmental stress-cracking agent.
6 1.72 kPa (5.06 0.25 psig).
7.2 For Procedure B:
6.4.1.4 Pressure Gages, calibrated to indicate a pressure of
7.2.1 Polyoxyethylated Nonylphenol, a stress-cracking
34.5 kPa (5.0 psig) with a precision of 0.34 kPa (0.05 psig). 3
agent.
NOTE 3—Amercury manometer is of benefit in calibrating the pressure
NOTE 4—Polyoxyethylated nonylphenol is hygroscopic and the undi-
gages, and monitoring precise pressure measurements.
luted agent should be kept tightly stoppered.
6.4.1.5 Air Valves.
7.2.2 Polyoxyethylated Nonylphenol Solution—Prepare a
10% solution, by volume, of the stress-cracking agent in
distilled water in sufficient volume to fill a minimum of fifteen
Selector Hand Sealing Iron (165W) made by Selector of Shelton, CT, or Super
473-mL (16-oz) containers to one third of overflow capacity
Sealer made by Clamco Div., Cleveland Detroit Corp., 5400 Brookpark Rd.,
Cleveland, OH, is suitable.
(178 mL).
Model 25 Owens-Illinois Spring Torque Tester, Owens-Illinois Glass Co.,
Toledo, OH, is suitable. NOTE 5—It has been found to be helpful due to the viscosity of the
D 2561 – 95 (2001)
stress-cracking agent, to prepare the solution at an elevated temperature.
the oven and the operator, if an inspection is being made.
A temperature of 50°C (120°F) has been found suitable.
Precautions to prevent this from happening are described in
11.1.4 and Note 10.
7.2.3 Dye Indicator Solution—Add 0.1% by weight of a
8.3 Care should be taken in handling the stress-cracking
wettingagent todistilledwater.Dissolve0.001%byweightof
agent since there is some possibility of its causing dermatitis.
Gentian Violet in the water.
8.4 Proper precautions should be taken in handling com-
NOTE 6—Since only about 0.1 mL(2 drops) of this solution is added to
pressed air equipment when following Procedure C.
each bottle, only a small volume is needed.
9. Test Specimen
7.3 For Procedure C:
7.3.1 Polyoxyethylated Nonylphenol, a stress-cracking
9.1 For Procedure A—A minimum of 15 blow-molded
agent. See Note 4.
containers, representative of the lot to be tested, and fitted with
7.3.2 Polyoxyethylated Nonylphenol Solution—Prepare a
a screw closure affording a leakproof seal, shall be selected.
33 ⁄3 % solution by volume, of the stress-cracking agent in
9.2 For Procedures B and C—A standard blow-molded
distilled water in sufficient volume to fill a minimum of fifteen
container shall be used for this test. It is a 473-mL (16-oz)
473-mL (16-oz) containers to one fourth of the overflow
cylindrical bottle weighing approximately 20 g, as shown in
capacity (133 mL). See Note 5.
Fig. 4. A minimum of 15 containers shall be selected as in
9.1.1. The minimum wall thickness of the container shall be
8. Safety Precautions
not less than 0.305 mm (12 mil). The pinch-off area of the
container shall not extend into the chime radius.
8.1 Proper precautions should be taken to prevent overheat-
ing of the containers during testing since some products which
NOTE 7—Test Methods D 374, modified to use a ball tip micrometer,
may be tested by Procedure A may cause an extreme pressure
may be used to measure the thickness of the container.
buildup in the container and could cause the container to
10. Conditioning
rupture explosively. Proper safety measures against over-
heating are described in Note 2.
10.1 Conditioning—Condition the test specimens at 23 6
8.2 Sometimes a container will fail by means of a small
2°C (73.4 6 3.6°F) and 50 6 5% relative humidity for not less
pinhole. Since the container is under pressure during the test,
than 40 h prior to test in accordance with Procedure A of
liquid may be forced out of the opening spraying the inside of
Practice D 618 for those tests where conditioning is required.
In cases of disagreement, the tolerances shall be 61°C
(61.8°F) and 62% relative humidity.
10.2 Test Conditions—Conduct all tests at 60°C, unless
Aerosol OT Solution from Fisher Scientific Corp., 203 Fisher Building,
instructed otherwise.
Pittsburgh, PA 15219, has been found suitable.
NOTE 1—Dimensions are in millimetres with inches in parentheses.
FIG. 4 Standard 473-mL (16-oz) Blown Container
D 2561 – 95 (2001)
11. Procedure finish up, in beakers containing sufficient undiluted stress-
cracking agent (7.2.1) to cover the chime area of the container.
11.1 Procedure A:
Check the temperature periodically for constancy.
11.1.1 Obtain a minimum of 15 containers of the type and
11.2.5 Inspectcontainersforfailuretoamaximumexposure
size chosen for test. Fill each to nominal capacity with the
time of 360 h as detailed in Procedure A, 11.1.6 and 11.1.7.
chosen test liquid, usually a proprietary liquid product or an
11.3 Procedure C:
aqu
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