ASTM D1922-00a

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation: D 1922 – 00a
Standard Test Method for
Propagation Tear Resistance of Plastic Film and Thin
Sheeting by Pendulum Method
This standard is issued under the fixed designation D 1922; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
1. Scope* D 374 Test Methods for Thickness of Solid Electrical Insu-
lation
1.1 This test method covers the determination of the
D 618 Practice for Conditioning Plastics for Testing
averageforcetopropagatetearingthroughaspecifiedlengthof
D 689 Test Method for Internal Tearing Resistance of Pa-
plastic film or nonrigid sheeting after the tear has been started,
per
using an Elmendorf-type tearing tester. Two specimens are
D 1004 Test Method for Initial Tear Resistance of Plastic
cited, a rectangular type, and one with a constant radius testing
Film and Sheeting
length. The latter shall be the preferred or referee specimen.
D 4000 Classification System for Specifying Plastic Mate-
1.2 Because of (1) difficulties in selecting uniformly iden-
rials
tical specimens, (2) the varying degree of orientation in some
E 691 Practice for Conducting an Interlaboratory Study to
plastic films, and (3) the difficulty found in testing highly
Determine the Precision of a Test Method
extensible or highly oriented materials, or both, the reproduc-
2.2 ISO Standard:
ibilityofthetestresultsmaybevariableand,insomecases,not
ISO 6383-2 Plastics—Film and Sheeting—Determination
good or misleading. Provisions are made in the test method to
of Tear Resistance—Part 2 Elmendorf Method
compensateforobliquedirectionaltearingwhichmaybefound
with some materials.
3. Summary of Test Method
1.3 The values stated in SI units are to be regarded as the
3.1 The force in grams required to propagate tearing across
standard. The values given in parentheses are for information
a film or sheeting specimen is measured using a precisely
only.
calibrated pendulum device. Acting by gravity, the pendulum
1.4 This standard does not purport to address all of the
swings through an arc, tearing the specimen from a precut slit.
safety concerns, if any, associated with its use. It is the
The specimen is held on one side by the pendulum and on the
responsibility of the user of this standard to establish appro-
other side by a stationary member. The loss in energy by the
priate safety and health practices and determine the applica-
pendulum is indicated by a pointer. The scale indication is a
bility of regulatory limitations prior to use. Specific precau-
function of the force required to tear the specimen.
tionary statements are given in Note 8.
NOTE 1—This standard and ISO 6383-2 are technically equivalent. 4. Significance and Use
4.1 This test method is of value in ranking relative tearing
2. Referenced Documents
resistance of various plastic films and thin sheeting of compa-
2.1 ASTM Standards:
rable thickness. Experience has shown the test to have its best
reliability on relatively less extensible films and sheeting.
Variable elongation and oblique tearing effects on the more
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
extensiblefilmsprecludeitsuseasapreciseproduction-control
and is the direct responsibility of Subcommittee D20.19 on Film and Sheeting.
tool for these types of plastics.This test method should be used
Current edition approved Nov. 10, 2000. Published January 2001. Originally
for specification acceptance testing only after it has been
published as D 1922 – 61 T. Last previous edition D 1922 – 00.
demonstrated that the data for the particular material are
This test method has been adapted from TAPPI Standard Method T 414M-49,
Internal Tearing Resistance of Paper. In testing certain plastic films, problems of
acceptably reproducible. This test method should be used for
reproducibility and interpretation of results are encountered which require special
treatment to make the test method of most value. This test method is revised here
specifically for use with plastic film and thin sheeting. For more complete
explanation of certain aspects of the equipment, its calibration and adjustment, refer Annual Book of ASTM Standards, Vol 10.01.
to TAPPI Standard Method T 414M-49. Annual Book of ASTM Standards, Vol 08.01.
The following additional references may be of interest in connection with this Annual Book of ASTM Standards, Vol 15.09.
test method: Annual Book of ASTM Standards, Vol 08.02.
Painter,E.V.,Chu,C.C.,andMorgan,H.M.,“TestingTextilesontheElmendorf Annual Book of ASTM Standards, Vol 14.02.
Tear Tester,” Textile Research Journal, Vol XX, No. 6, June 1950, pp. 410–417. Available from American National Standards Institute, 11 W. 42nd St., 13th
Elmendorf, A., “Strength Test for Paper,” Paper, Vol 26, April 21, 1920, p. 302. Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
D 1922 – 00a
service evaluation only after its usefulness for the particular pendulum shall carry a circumferential scale, graduated from 0
application has been demonstrated with a number of different to 100 % of the machine capacity so as to read against the
films. pointer the average force required to tear a specimen 43 mm
4.2 This test method has been widely used as one index of (1.7 in.). The pointer and scale may be replaced by an
the tearing resistance of plastic film and thin sheeting used in electronic digital readout. Digital readouts are available which
packaging applications.While it may not always be possible to will give test results directly in millinewtons, directly in
correlate film tearing data with its other mechanical or tough- grams-force, or in percent of pendulum capacity. With the
ness properties, the apparatus of this test method provides a pendulum in its initial position ready for test, separate the two
controlled means for tearing specimens at straining rates clamps by an interval of 2.54 mm (0.10 in.). So align them that
approximating some of those found in actual packaging ser- the specimen clamped in them lies in a plane perpendicular to
vice. the plane of oscillation of the pendulum with the edges of the
4.3 Due to orientation during their manufacture, plastic jawsgrippingthespecimeninahorizontalline,aperpendicular
films and sheeting frequently show marked anisotropy in their to which through the axis of suspension of the pendulum is
resistancetotearing.Thisisfurthercomplicatedbythefactthat 102.7 6 0.05 mm (4.044 6 0.002 in.) in length and makes an
some films elongate greatly during tearing, even at the rela- angle of 27.5° with the plane of the film specimen. The
tively rapid rates of loading encountered in this test method. clamping surface in each jaw shall be at least 25.4 mm (1 in.)
The degree of this elongation is dependent in turn on film in width and at least 12.7 mm (0.5 in.) in depth.
orientation and the inherent mechanical properties of the 5.1.5 Capacity—Instruments of several capacities, 1960,
polymer from which it is made. These factors make tear 3920, 7840, 15 600, 31 360, 62 720 mN (200, 400, 800, 1600,
resistance of some films reproducible between sets of speci- 3200, 6400 gf), and perhaps others are available. These
mens to 65 % of the mean value, while others may show no capacities can be achieved by individual instruments, inter-
better reproducibility than 650 %. changeable pendulum sectors, or augmenting weights.
4.4 Data obtained by this test method may supplement that 5.2 Template, Die, or Shear-Type Cutter, for cutting
from Test Method D 1004D 1004, wherein the specimen is specimens.
strained at a rate of 50 mm (2 in.) per min. However, specimen 5.3 Razor Blades, single-edged, for cutting specimens
geometry and testing speed of the two test methods are where a template is used.
dissimilar.Therateoftearinginthistestmethod,whilevarying 5.4 Thickness-Measuring Device—A suitable micrometer,
as a function of resistance to tear, is in the range from 7.6 to 46 or other thickness gage, reading to 0.0025 mm (0.0001 in.) for
m (300 to 1800 in.)/min. measuring the thickness of test specimens. The pressure
4.5 There is not a direct, linear relationship between tearing exerted by the gage on the specimen being measured shall not
force and specimen thickness. Data from this test method are distort or deform the specimen. For thin films, ≤0.025 mm
expressed as tearing force in millinewtons (or grams-force, if (0.001 in.), or films that exhibit visual deformation during
desired), with specimen thickness also reported. But sets of measurement, a maximum pressure of 70 kPa (10 psi) is
data from specimens of dissimilar thickness are usually not recommended. For thicker or stiffer films, the pressure shall be
comparable. Therefore, only data at the same thickness can be between 160 and 185 kPa (23 and 27 psi), in accordance with
compared. Method C of Test Methods D D 374374.
4.6 For many materials, there may be a specification that
6. Test Specimens
requires the use of this test method, but with some procedural
modifications that take precedence when adhering to the
6.1 Test specimens shall be cut, as shown in Fig. 1, to form
specification. Therefore, it is advisable to refer to that material
a constant-radius testing length. This shall be the preferred or
specification before using this test method. Table 1 of Classi-
referee specimen type since its geometry automatically com-
fication System D 4000D 4000 lists the ASTM materials
pensates for the problem of oblique tearing (Note 2 and Note
standards that currently exist.
3).Alternatively, specimens shall be cut to form a rectangle 76
mm (3 in.) or more in width by 63 mm (2.5 in.) in length and
5. Apparatus
plainlymarkedtodenoteintendeddirectionoftear.The63-mm
5.1 Pendulum Impulse-Type Testing Apparatus, consisting specimen dimension shall be the direction of tear. Two sets of
of the following: specimens shall be cut from each sample so that their sides are
5.1.1 Stationary Clamp. parallel to (1) the machine direction and (2) the transverse
5.1.2 Movable Clamp, carried on a pendulum, preferably direction, respectively, of the material being tested. Enough
formed by a sector of a wheel or circle, free to swing on a ball specimens shall be cut in each direction to provide a minimum
bearing or other substantially frictionless bearing. of ten tear strength determinations.
5.1.3 Stop Catch, for holding the pendulum in a raised
NOTE 2—Specimens having constant-radius testing lengths are de-
position and for releasing it instantaneously.
signed to correct for oblique directional tearing encountered in certain
5.1.4 Indicating Device, for registering the maximum arc
anisotropic, elastomeric films, and nonrigid sheeting. For purposes of
through which the pendulum swings when released. The
The TA63 Sample Cutter, Catalog No. 98, available from the Thwing-Albert
Equipment available from the Thwing-Albert Instrument Co., Philadelphia, PA Instrument Co., Philadelphia, PA 19144, has been found satisfactory for cutting
19144, meets the requirements for this apparatus. specimens.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
D 1922 – 00a
This bearing will not necessarily allow the pendulum sector to
make 20 complete oscillations as the older one did. This does
not mean that there is excess friction in the pendulum swing.
These newer bearings should not be oiled. Consult the instruc-
tions supplied with the instrument for guidance.
7.2 Pointer Friction—Check the pointer friction as follows:
Set the pointer at zero reading on the scale before releasing the
sector, and after release see that the pointer is not pushed more
than three scale divisions beyond zero.Areading of more than
three divisions indicates excessive pointer friction and the
pointer should be removed, the bearing wiped clean, and a
trace of oil or petroleum jelly applied. When the pointer
friction has been reduced, finally adjust the pointer stop.
7.3 Pointer Zero Reading—To check the pointer for its zero
point, level the apparatus so that, with the sector free, the line
on the sector indicating the vertical point of suspension
coincides with a corresponding point on the base of the
apparatus, usually placed on the stop mechanism. After level-
ing, operate the apparatus several times with nothing in the
FIG. 1 Constant-Radius Test Specimen for Tear Resistance Test
jaws, the movable jaw being closed, to ascertain whether the
pointer registers zero with no load. If zero is not registered,
adjust the position of the pointer stop by means of the pointer
specimen selection, oblique tearing is defined as tearing in a curved or
stop thumb screw until a zero reading is obtained.
straight line that deviates more than 9.5 mm ( ⁄8 in.) from the vertical line
of intended tear.
NOTE 3—Certain film and sheeting specimens showing oblique tearing
8. Verification of Scale
may yield data of poor reproducibility because the axis of maximum
8.1 The scale may be verified either by the procedure
orientation varies as much as 30° from the nominal machine direction.
When this is suspected, the sample may be examined by crossed Polaroid
described inTest Method D 689D 689 and repeated here, or by
plates to determine this direction of maximum orientation and the
the method which uses the Elmendorf check weights obtain-
specimens cut along the axis of anisotropy for testing parallel and normal
able from the manufacturer. The method in Test Method
to it.
D 689D 689 is relatively time-consuming and complicated.
6.2 Where a metal template is used, the film or sheeting
The check weight method is relatively simple.
shall be placed on a hard surface. The template shall be held
8.2 Test Method D 689D 689 Procedure:
over it and the specimens cut out using a single-edged razor
8.2.1 To verify the scale, first mark the center of gravity of
blade.
the weight (including means of attaching) by a punched dot on
6.3 Whenthespecimeniscutout,aslit20mm(0.8in.)deep
the face of the weight. Then clamp a known weight in grams,
may be made at the center of the edge perpendicular to the
W, to the radial edge of the sector beneath the jaws.
direction to
...