ASTM D3420-95(2002)
(Test Method)Standard Test Method for Pendulum Impact Resistance of Plastic Film
Standard Test Method for Pendulum Impact Resistance of Plastic Film
SIGNIFICANCE AND USE
Like other techniques to measure toughness, this test method provides a means to determine parameters of a material at strain rates closer to some end-use applications than provided by low-speed uniaxial tensile tests. Dynamic tensile behavior of a film is important, particularly when the film is used as a packaging material. The same uncertainties about correlations with thickness that apply to other impact tests also apply to this test (see section 3.4 of Test Methods D 1709). Hence, no provision for rationalizing to unit thickness is provided. Also, no provision is made for testing at non-ambient temperatures.
This test method includes two procedures, similar except with regard to sample size: Procedure A for 60-mm diameter and Procedure B for 89-mm diameter (commonly called the “Spencer”). The data have not been shown relatable to each other.
Several impact test methods are used for film. It is sometimes desirable to know the relationships among test results derived by different methods. A study was conducted in which four films made from two resins (polypropylene and linear low-density polyethylene), with two film thicknesses for each resin, were impacted using Test Methods D 1709 (Method A), Test Method D 3420 (Procedures A and B), and Test Method D 4272. The test results are shown in Appendix X2. Differences in results between Test Methods D 1709 and D 4272 may be expected since Test Methods D 1709 represents failure initiated energy while Test Method D 4272 is initiation plus completion energy. Some films may show consistency when the initiation energy is the same as the total energy. This statement and the test data also appear in the significance and appendixes sections of Test Methods of D 1709 and D 4272.
SCOPE
1.1 This test method covers the determination of resistance of film to impact-puncture penetration. Knowledge of how the impact energy is absorbed by the specimen while it is deforming under the impact loading, and the behavior of the specimen after yielding, is not provided by this test. No provision is made for nonambient temperatures in this test method.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 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 hazards statements are given in Section 7.
Note 1—lThere is no similar or equivalent ISO standard.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D3420–95 (Reapproved 2002)
Standard Test Method for
Pendulum Impact Resistance of Plastic Film
This standard is issued under the fixed designation D 3420; 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 E 691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This test method covers the determination of resistance
of film to impact-puncture penetration. Knowledge of how the
3. Terminology
impact energy is absorbed by the specimen while it is deform-
3.1 Definitions—Definitions of terms relating to plastics not
ing under the impact loading, and the behavior of the specimen
otherwise described in this test method shall be in accordance
afteryielding,isnotprovidedbythistest.Noprovisionismade
with Terminology D 883.
for nonambient temperatures in this test method.
3.2 Definitions of Terms Specific to This Standard:
1.2 The values stated in SI units are to be regarded as the
3.2.1 failure completion energy—the energy necessary to
standard.
initiate failure plus the energy necessary to cause complete
1.3 This standard does not purport to address all of the
rupture to the test specimen.
safety concerns, if any, associated with its use. It is the
3.2.2 failure initiated energy—the energy necessary to be-
responsibility of the user of this standard to establish appro-
gin failure of the test specimen.
priate safety and health practices and determine the applica-
3.2.3 pendulum impact resistance—the resistance to failure
bility of regulatory limitations prior to use. Specific hazards
of plastic film is measured by loss in mechanical work capacity
statements are given in Section 7.
due to the expenditure of kinetic energy by a pendulum.
NOTE 1—There is no similar or equivalent ISO standard.
4. Summary of Test Method
2. Referenced Documents
4.1 The energy necessary to burst and penetrate the center
2.1 ASTM Standards:
of a specimen, mounted between two plates with a circular
D 374 Test Methods for Thickness of Solid Electrical Insu-
aperture, is measured by the loss in mechanical work-capacity
lation
due to the expenditure of kinetic energy by a pendulum, the
D 618 Practice for Conditioning Plastics and Electrical
rounded probe of which passes through the test specimen.
Insulating Materials for Testing
Corrections for “toss factor” or kinetic energy imparted to the
D 883 Terminology Relating to Plastics
puncture fragment of the test specimen are not made, as only
D 1709 Test Methods for Impact Resistance of Plastic Film
tiny masses are involved. The pendulum head hits the speci-
by the Free-Falling Dart Method
men with a maximum velocity of about 74 m/min and a
D 1922 Test Method for Propagation Tear Resistance of
maximum energy of about 5 J (50 cm·kgf).
Plastic Film and Thin Sheeting by Pendulum Method
D 4272 Test Method for Total Energy Impact of Plastic 5. Significance and Use
Films by Dart Drop
5.1 Like other techniques to measure toughness, this test
E 177 Practice for Use of the Terms Precision and Bias in
methodprovidesameanstodetermineparametersofamaterial
ASTM Test Methods
at strain rates closer to some end-use applications than pro-
vided by low-speed uniaxial tensile tests. Dynamic tensile
1 behavior of a film is important, particularly when the film is
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
used as a packaging material. The same uncertainties about
and is the direct responsibility of Subcommittee D20.19 on Film and Sheeting.
Current edition approved June 15, 1995. Published August 1995. Originally
correlations with thickness that apply to other impact tests also
published as D 3420 – 75. Last previous edition D 3420 – 94.
apply to this test (see section 3.4 of Test Methods D 1709).
The current edition includes the addition of Note 1 and Section 15, Keywords.
Hence, no provision for rationalizing to unit thickness is
Annual Book of ASTM Standards, Vol 10.01.
Annual Book of ASTM Standards, Vol 08.01. provided.Also,noprovisionismadefortestingatnon-ambient
Annual Book of ASTM Standards, Vol 08.02.
temperatures.
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.
D3420–95 (2002)
5.2 This test method includes two procedures, similar ex-
gf J (cm·kgf)
200 0.169 (1.7)
cept with regard to sample size: Procedure A for 60-mm
400 0.338 (3.4)
diameter and Procedure B for 89-mm diameter (commonly
800 0.675 (6.8)
called the “Spencer”). The data have not been shown relatable
1600 1.35 (13.5)
3200 2.70 (27)
to each other.
5.3 Several impact test methods are used for film. It is
6.2 Micrometer, reading to 60.00025 mm (60.00001 in.)
sometimes desirable to know the relationships among test
for measuring specimen thickness.
results derived by different methods.Astudy was conducted in
6.3 Specimen Cutter.
which four films made from two resins (polypropylene and
7. Hazards
linear low-density polyethylene), with two film thicknesses for
eachresin,wereimpactedusingTestMethodsD 1709(Method 7.1 In Procedure A do not release the pendulum manually
when the temperature chamber is in position unless the unit is
A), Test Method D 3420 (Procedures A and B), and Test
Method D 4272. The test results are shown in Appendix X2. pluggedinandenergized;otherwisethechamberdoorswillnot
open and will be struck by the pendulum ball. In either
Differences in results between Test Methods D 1709 and
D 4272maybeexpectedsinceTestMethodsD 1709represents procedure, be sure that the hands are kept out of the pendulum
failure initiated energy while Test Method D 4272 is initiation path when it is in the cocked position.
plus completion energy. Some films may show consistency
8. Test Specimens
when the initiation energy is the same as the total energy. This
8.1 Obtain samples that are of uniform thickness and
statement and the test data also appear in the significance and
consistency, flat, free of defects, and representative of the
appendixes sections of Test Methods of D 1709 and D 4272.
material to be tested.
6. Apparatus
NOTE 2—Although the scope of this test method is for films [sheeting
#0.25 mm (#10 mils)], samples up to 0.40 mm (15 mils) have been
6.1 Tester, having a heavy base plate (to be bolted down
tested, representing the upper limit imposed by the design of the clamp,
when the higher energy ranges are used), housing, and frame
without damage to the pendulum.
upon which is located a free-swinging pendulum with an
8.2 From throughout the sample, cut at least five specimens,
impact head. The dimensions for the impact heads for Proce-
100-mm (4-in.) diameter circular, or 100 by 100-mm (4 by
dures A and B are as follows:
4-in.) square or larger if clamps require.
6.1.1 Procedure A—Hemispherical, having a smooth sur-
face of 12.7-mm (0.5-in.) radius and 25.4-mm (1.0-in.) diam-
9. Preparation of Apparatus
eter, and
9.1 Procedure A:
6.1.2 Procedure B—Having a smooth surface of 12.7-mm
9.1.1 Level the instrument carefully, using the level located
(0.5-in.) radius, and 19.0-mm (0.75-in.) diameter, which when
on the instrument (assuming the level has been properly
released from the starting position punctures the material. The
mounted and calibrated).
specimen is clamped between two plates with a circular
9.1.2 Attachthelargestweight(forexample,“50cm·kgf”or
aperture of 60 6 0.3-mm (2.362 6 0.012-in.) diameter in the
“5.0 J”).
center for ProcedureAand 89 6 0.5 mm (3.50 6 0.02 in.) for
9.1.3 Adjust the auxiliary weights on the rear of the pendu-
Procedure B. Several types of clamps are available on the
lum so the pendulum hangs vertically when free.
Spencer testers: a slip-ring type, manual-tightening type with
9.1.4 Set the pointer on Point P of the scale, and adjust the
O-ring, and air-operated type with O-ring. The O-ring type,
arm that moves the pointer so it just contacts the pointer in this
either manual or air-operated, is recommended to minimize
position.
slippage of the test specimen. The air-operated O-ring clamp
9.1.5 Release the pendulum from its latched position and
shall be the referee-type.
allow to swing freely (with no sample). The pointer should
6.1.3 Calibrated Dial, to record the energy necessary to
cometowithinonescaledivisionofthezeropoint.Ifthisisnot
burst and penetrate the specimen (a scale and pointer with
the case, the bearing likely needs cleaning.
indicating follower and attachable auxiliary weights to give
9.1.6 Whenever the range of test is changed, the instrument
suitable energy scales). Four energy scales have been found
must be reset so the “pointer pusher” is against the pointer with
suitable, 0.5, 1.0, 2.5, and 5.0 J (5, 10, 25, and 50 cm·kgf), for
the pointer at P and the pendulum hanging freely. This is done
Procedure A through the use of attachable auxiliary weights.
by repositioning the auxiliary weights.
For Procedure B, a modified Elmendorf tester having a
9.1.7 Select the energy range and attach the correct weights
capacity of 1600 gf (3200 gf with auxiliary weight) is normally
to the pendulum. Do not use a higher range than is necessary
used. Pendulums of 200, 400, and 800 gf are also available.
to ensure rupture of the film under test.
Equivalent energy capacities for these force capacities are as
9.2 Procedure B:
follows:
9.2.1 Locate the instrument on a level surface.
9.2.2 Zero the instrument in accordance with Test Method
D 1922 if the instrument has a pointer, or refer to the
Atester of the ProcedureAtype is available fromTesting Machines Inc. (TMI),
manufacturer’s recommendations if it has a digital readout.
400 BayviewAve.,Amityville, Long Island, NY11701.Atester of the Procedure B
9.2.3 Select the weight so that the scale readings do not fall
type is available from Thwing-Albert Instrument Co., 10960 Dutton Road, Phila-
delphia, PA 19154. on the extreme ends of the range when testing specimens.
D3420–95 (2002)
9.2.4 Slippage of the specimen in the clamp when it is 11.2.1 Determine the thickness of the specimens to the
struck by the impact head is a recognized cause for testing nearest 0.00025 mm (0.01 mil), in accordance with Test
error. Slippage may be minimized by giving adequate attention
Methods D 374.
to the condition of the clamp and its operation. Any slippage
11.2.2 Place a specimen in the specimen holder.
that occurs can be detected by marking each specimen with a
11.2.3 Set the pendulum in its raised latched position. Zero
wax pencil near the clamp after it is installed in test position,
the indicator and mark the specimen as described in 9.2.4.
and by observing the marking after the test for any change of
11.2.4 Release the pendulum by pressing down firmly on
location.
the latch stop. Be sure the pendulum completely clears the stop
NOTE 3—AcalibrationdiscussionisgiveninAppendixX1forthetester
as it swings, or it will be impeded and give a false reading.The
in Procedure A.
impact head shall pass completely through the specimen. If it
does not, a weight shall be added to the pendulum to provide
10. Conditioning
more energy, or a thinner specimen shall be used.
10.1 Condition the test specimens at 23 6 2°C (73.4 6
11.2.5 Catchthependulumwiththehandonitsreturnswing
3.6°F) and 50 6 5 % relative humidity in accordance with
and reset it in the raised latched position.
Procedure A of Practice D 618, for those tests where condi-
11.2.6 Record the scale reading.
tioning is required. In cases of disagreement, the tolerances
11.2.7 Remove the ruptured test specimen from the clamp.
shall be 61°C (61.8°F) and 62 % relative humidity.
Observe the tested specimen for slippage. If slippage has
occurred, the test should be repeated using a new specimen.
11. Procedure
Test the remaining specimens as described above.
11.1 Procedure A:
11.1.1 Determine the thickness of the specimens to the
12. Calculation
nearest 0.00025 mm (0.01 mil), in accordance with Test
Methods D 374.
12.1 For each specimen tested, calculate impact energy as
11.1.2 Set the control switches properly.
follows:
12.1.1 For Procedure A:
NOTE 4—In the TMI instrument (Procedure A): power switch, ON;
selector switch, MANUAL; temperature control switch (for ambient
temperature), OFF.
~scale reading in cm·kgf!
E 5 (1)
11.1.3 Place a specimen in the specimen holder.
10.2
11.1.3.1 Turn the knob and pull it outward to remove
pressure from the hinged plate of the specimen holder. Open
where E equals energy to rupture, J.
thespecimenholder,pushtheknobforward,andturnittoexert
12.1.2 For Procedure B:
a gripping pressure on the specimen.
11.1.3.2 If the specimen has excessive curl, tape it in
position in the specimen holder.
E 5 ~R/100! 3 C (2)
11.1.4 Set the pendulum to its latched position by raising it
completely with the hand and then gently releasing it, making
where:
certain it engages the latch. This movement ensures the proper
E = energy to rupture, J,
functioning of the relay which will open the temperature
C = apparatuscapacity,J(0.17,0.34,0.67,1.35,or2.7J),
chamber doors at the proper instant during the test.
and
11.1.5 Place the specimen holder in the instrument and
R = scale reading on the 0 to 100 scale.
tighten it in place with the tightening knobs.
11.1.6 Set the movable pointer to P on the graduated scale.
13. Report
11.1.7 For an ambient temperature test, the pendulum will
release when the MANUAL button is pushed. 13.1 Report the following information:
11.1.8 After the swing, determine if the film specimen
13.1.1 Complete identification of the sample,
ruptured. If not, record this fact. If so, read the position of the
13.1.2 The capacity of the pendulum in joules (or
movable pointer on the appropriate scale (corresponding to the
centimetres-kilogram-force) and procedure used (A or B,
weights used) and record this value in joules or centimetres-
differing in sample size (see 5.2)),
kilograms-force.
13.1.3 Total number of specimens tested per sample,
NOTE 5—It is wise to make trial tests, especially for thicker specimens,
13.1.4 The average impact strength in joules or centimetres-
by dropping the pendulum from a partial arc, so as to avoid damage to the
kilograms-force,
pendulum (bending). If damage is suspected, the impact point should be
13.1.5 The average thickness in micrometres or mils,
checked for proper centering by inserting a clear specimen in the holder
and allowing the impact head to rest against it.
13.1.6 If required, the calculated standard deviation of the
values of the impact strengths of the spe
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