ASTM D1709-98

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 1709 – 98
Standard Test Methods for
Impact Resistance of Plastic Film by the Free-Falling Dart
Method
This standard is issued under the fixed designation D 1709; 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.
ods for testing these materials. Anyone interested in participating in a Task
1. Scope *
Group should contact the Chairman of Subcommittee D20.19 through
1.1 These test methods cover the determination of the
ASTM Headquarters.
energy that causes plastic film to fail under specified conditions
NOTE 2—This test method is technically equivalent to ISO 7765-1:
of impact of a free-falling dart. This energy is expressed in
1988, with the exception of a larger tolerance on the drop height in Test
terms of the weight (mass) of the missile falling from a Method B. Also, the ISO method does not allow the alternative testing
technique described in Section 11 of this test method.
specified height which would result in 50 % failure of speci-
mens tested.
1.5 This standard does not purport to address the safety
1.2 Two test methods are described:
concerns, if any, associated with its use. It is the responsibility
1.2.1 Test Method A employs a dart with a 38.0 6 1-mm
of the user of this standard to establish appropriate safety and
(1.50 6 0.05-in.) diameter hemispherical head dropped from a
health practices and determine the applicability of regulatory
height of 0.66 6 0.01 m (26.0 6 0.4 in.). This test method may
limitations prior to use.
be used for films whose impact resistances require masses of
2. Referenced Documents
about 50 g or less to about 2 kg to fracture them.
1.2.2 Test Method B employs a dart with a 50 6 1-mm
2.1 ASTM Standards:
(2.0 6 0.01, −0.07-in.) diameter hemispherical head dropped
D 374 Test Methods for Thickness of Solid Electrical Insu-
from a height of 1.50 6 0.03 m (60.0 + 0.25, −1.70 in.). Its
lation
range of applicability is from about 0.3 kg to about 2 kg.
D 618 Practice for Conditioning Plastics and Electrical
1.3 Two testing techniques are described:
Insulating Materials for Testing
1.3.1 The standard technique is the staircase method. By
D 883 Terminology Relating to Plastics
this technique, a uniform missile weight increment is employed
D 1248 Specification for Polyethylene Plastics Molding and
during test and the missile weight is decreased or increased by
Extrusion Materials
the uniform increment after test of each specimen, depending
D 3420 Test Method for Dynamic Ball Burst (Pendulum)
upon the result (fail or not fail) observed for the specimen.
Impact Resistance of Plastic Film
1.3.2 The alternative technique provides for testing speci-
D 4272 Test Method for Total Energy Impact of Plastic
mens in successive groups of ten. One missile weight is
Films by Dart Drop
employed for each group and missile weight is varied in
E 177 Practice for Use of the Terms Precision and Bias in
uniform increments from group to group.
ASTM Test Methods
1.3.3 The staircase technique and the alternative technique
E 691 Practice for Conducting an Interlaboratory Study to
give equivalent results both as to the values of impact failure
Determine the Precision of a Test Method
weight which are obtained and as to the precisions with which
2.2 ISO Standard:
they are determined.
ISO 7765:1988 Plastic Film and Sheeting—Determination
1.4 The values stated in SI units are to be regarded as
of Impact Resistance by the Free Falling Dart Method—
standard. The values stated in parentheses are for information
Part 1: Staircase Method
only.
3. Terminology
NOTE 1—Tests on materials that do not break, for any reason, are not
3.1 Definitions—For definitions related to plastics, see
considered to be valid. It has been noted that certain materials may stretch
Terminology D 883.
so far as to bottom out at the base of certain test instruments without
actually rupturing. Subcommittee D20.19 is currently considering meth-
3.2 Definitions of Terms Specific to This Standard:
Annual Book of ASTM Standards, Vol 10.01.
1 3
These test methods are under the jurisdiction of ASTM Committee D20 on Annual Book of ASTM Standards, Vol 08.01.
Plastics and are the direct responsibility of Subcommittee D20.19 on Film and Annual Book of ASTM Standards, Vol 08.02.
Sheeting. Annual Book of ASTM Standards, Vol 14.02.
Current edition approved July 10, 1998. Published January 1999. Originally Available from American National Standards Institute, 11 W. 42nd St., 13th
published as D 1709 – 59 T. Last previous edition D 1709 – 97. Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 1709
3.2.1 failure—any break through the film that can be ob- 5.1.1.1 The lower or stationary half of the clamp shall be
served readily by feeling or by viewing the specimen under mounted rigidly so that the plane of the specimen is horizontal.
backlighted condition.
5.1.1.2 The upper or movable part of the clamp shall be
3.2.2 impact failure weight—that missile weight, estimated
designed to maintain positive and plane contact with the lower
statistically, at which 50 % of the specimens would fail in the
part of the clamp when in position. The clamps shall be
specified test.
provided with suitable means of maintaining sufficient contact
3.2.3 missile weight—the weight (mass) of the dart plus the
to hold the film sample firmly in place during the test.
total value of incremental weights attached plus the locking
Pneumatically operated clamps have been successfully em-
collar.
ployed.
5.1.1.3 Rubber-like gaskets may be affixed to the specimen
4. Significance and Use
contact surfaces of both clamps to provide a cushion which
4.1 Test Methods A and B are used to establish the weight of
minimizes thickness variation effects. Rubber gasketing
the dart when 50 % of the specimens fail under the conditions
3.0 6 1 mm (0.125 + 0.025, −0.04 in.) thick, of 50 to 60 Shore
specified. Data obtained by one test method cannot be com-
A durometer hardness, 125 6 2.0 mm (5.00 + 0.00, −0.15 in.)
pared directly with the other test method nor with those
in inside diameter and 150 6 3.0 mm (6.0 + 0.02, −0.2 in.) in
obtained from tests employing different conditions of missile
outside diameter has been found satisfactory for this purpose.
velocity, impinging surface diameter, effective specimen diam-
5.1.1.4 Slippage of films greater than 0.10 mm (0.004 in.) in
eter, and thickness. The values obtained by these test variables
thickness may be minimized or eliminated by securing crocus
are highly dependent on the method of film fabrication.
cloth or 50D garnet abrasive paper to the gaskets with double
4.2 The results obtained by Test Methods A and B are
sensitive tape so that the abrasive surface is in direct contact
greatly influenced by the quality of film under test. The
with the film. There should be sufficient clamping force to
confidence limits of data obtained by this procedure can,
eliminate detectable slippage. Other means of reducing slip-
therefore, vary significantly, depending on the sample quality,
page such as additional clamping devices or positive clamping
uniformity of film gage, die marks, contaminants, etc. (see
surfaces may be used provided that the film is not weakened at
Section 15).
the inside wall of the specimen clamps and that the effective
4.3 Test Methods A and B have been found useful for
diameter of 125 6 2.0 mm (5.00 + 0.00, −0.15 in.) of the film
specification purposes. Correlation between test results and
is not changed.
field performance can usually be established.
5.1.2 Dart Release Mechanism, capable of supporting a
4.4 The impact resistance of plastic film, while partly
2-kg weight shall be used for supporting and releasing the dart
dependent on thickness, has no simple correlation with sample
assembly. It shall be equipped with a centering device, such as
thickness. Hence, impact values cannot be normalized over a
a removable plumb bob, to ensure a reproducible drop. Either
range of thickness without producing misleading data as to the
an electromagnetic- or pneumatic-operated release mechanism
actual impact resistance of the material. Data from these test
may be used.
methods are comparable only for specimens that vary by no
5.1.3 Positioning Device—The apparatus shall be able to
more than 625 % from the nominal or average thickness of the
drop the dart from heights of 0.66 6 0.01 m (26.0 6 0.4 in.)
specimens tested.
for Test Method A and 1.50 6 0.03 m (60.0 + 0.25, −1.70 in.)
4.5 Several impact test methods are used for film. It is
for Test Method B. The distance between the impinging surface
sometimes desirable to know the relationships among test
of the dart head and the surface of the test specimen is
results derived by different test methods. A study was con-
considered to be the drop height. The dart shall be positioned
ducted in which four films made from two resins (polypropy-
vertically above the center of the test specimen.
lene and linear low-density polyethylene), with two film
5.1.4 Micrometer, accurate to 60.0025 mm (60.0001 in.)
thicknesses for each resin, were impacted using Test Methods
in the range from 0.0025 mm (0.0001 in.) to 1 mm (0.4 in.) for
D 1709 (Method A), D 3420 (Procedures A and B), and
measuring specimen thickness (see Test Methods D 374).
D 4272. The test results are shown in the Appendix. Differ-
5.1.5 Cushioning and Shielding Devices, to protect person-
ences in results between Test Methods D 1709 and D 4272 may
nel and to avoid damaging the impinging surface of the dart.
be expected since Test Methods D 1709 represents failure
These devices shall not interfere with the dart or the specimen
initiated energy, while Test Method D 4272 is initiation plus
prior to penetrating the specimen.
completion energy. Some films may show consistency when
5.1.6 Collar with inside diameter of approximately 7 mm
the initiation energy is the same as the total energy. This
(0.28 in.) and with set screw for securing collar to dart shaft.
statement and the test data also appear in the significance
5.2 Darts for Test Methods A and B shall have hemispheri-
sections and appendixes of Test Methods D 3420 and D 4272.
cal heads, each fitted with a 6.5 6 1-mm (0.25 + 0.04, −0.03-
5. Apparatus
in.) diameter shaft at least 115 mm (4.5 in.) long to accommo-
5.1 The apparatus shall be constructed essentially as shown date removable incremental weights. Each dart weight shall be
in Fig. 1, using the following components common to both test known to 60.5 % relative. Dart head surfaces shall be free of
methods: nicks, scratches, or other irregularities. The shaft shall be
5.1.1 Specimen Clamp—A two-piece annular specimen attached to the center of the flat surface of the head with its
clamp having an inside diameter of 125 6 2.0 mm (5.0 + 0.0, longitudinal axis perpendicular to the surface. If an electro-
−0.15 in.) and conforming to the following requirements: magnet is used, the shaft shall be made of material that is not
D 1709
NOTE—Legend Dart Assembly:
A. Steel shaft tip 6.5 6 1 mm (0.25 + 0.04, −0.03 in.) OD by 12.5 6 0.2 mm (0.50 + 0.00, −0.02 in.) long.
B. Dart shaft: 6.5 6 1 mm (0.25 + 0.04, −0.03 in.) OD and at least 115 mm (4.5 in.) long: ⁄4–20 thd. (N.C.) 12.5 6 0.2 mm (0.50 + 0.00, −0.02 in.) long
on bottom: No. 5–40 thd. (N.F.) for steel tip.
C. Hemispherical head: Method A—38.0 6 0.06 mm (1.50 6 0.005 in.) in diameter. Method B—50 6 0.08 mm (2.0 6 0.005 in.) in diameter.
D. Removable weights.
E. Collar and screw.
FIG. 1 Apparatus for Free-Falling Dart Impact Test for Plastic Film
magnetic and shall have a steel tip 125 6 0.2 mm (0.50 + 0.00, in.) diameter weights.
−0.02 in.) long at the end held by the electromagnet.
Number Weight, g
2 or more 5
5.2.1 For Test Method A, the dart head shall be 38.0 6 0.06
mm (1.50 6 0.005 in.) in diameter. It may be constructed of
smooth, polished aluminum, phenolic, or other low-density 860
material of similar hardness.
5.3.2 For Test Method B, 45.0 6 1-mm (1.75 + 0.06, −0.02-
5.2.2 For Test Method B, the dart head shall be 50 6 0.08
in.) diameter weights.
mm (2.0 6 0.005 in.) in diameter. It may be constructed of
Number Weight, g
smooth, polished stainless steel or other material of similar
2 or more 15
durability. 845
5.3 Incremental Weights for Test Methods A and B shall be
of stainless steel or brass and cylindrical in shape. Each shall
5.3.3 Optionally, additional weights, each 120 g 6 0.5 %
have a center hole 6.6 + 1.0, −0.00 mm (0.26 + 0.03, −0.00 in.)
for Test Method A or 180 g 6 0.5 % for Test Method B, may
in diameter. The thickness of each shall be adjusted to obtain
be constructed for use if it is necessary to extend the missile
the specified weight within 60.5 %. The diameter of the
weight beyond that attainable when using all weights in the
weights shall not exceed the diameter of the dart head.
standard set.
Suggested combination of weights for the specified diameters
6. Test Specimen
are as follows:
5.3.1 For Test Method A, 31.5 6 1-mm (1.25 + 0.03, −0.05- 6.1 Test specimens shall be large enough to extend outside
D 1709
the specimen clamp gaskets at all points. The specimens shall the inside wall of the upper clamp. Apply only the pressure of
be representative of the film under study and shall be taken the pen itself to the film. (Caution—For safety reasons, the
from the sheet or tube in a manner representative of sound dart should not be in the dart release mechanism while drawing
sampling practice. This is to ensure that the whole of the sheet the circle.) After the dart is dropped and prior to removing the
be represented in the test unless such sampling constitutes a plastic film, draw another circle using a ball-point pen of
variable under study. another color. If the lines are drawn, distinct double lines at any
6.2 The specimens shall be free of pinholes, wrinkles, folds, point on the circumference show that slippage has occurred.
or other obvious imperfections, unless such imperfections 8.2.2 If crocus cloth or sandpaper is affixed to the gaskets to
constitute variables under study. effect greater gripping, determine slippage simply by inspect-
ing the clamped film area after impact for evidence of scratch
7. Conditioning
marks produced as slippage occurred.
7.1 Conditioning—Follow the conditioning requirements
STAIRCASE TESTING TECHNIQUE
specified in the ma
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