INTERNATIONAL STANDARD
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXAYHAPOfiHAfl OPTAHM3AqMfl IlO CTAH~APTM3A~MM
Plastics film and sheeting - Determination of impact
resistance by the free-falling dart method
Part 1:
Staircase methods
IS077651 9988 (El
Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of
national standards bodies (IS0 member bodies). The work of preparing International
Standards is normally carried out through IS0 technical committees. Each member
body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
iTeh STANDARD PREVIEW
the IS0 Council. They are approved in accordance with IS0 procedures requiring at
least 75 % approval by the member bodies voting.
International Standard
(standards.iteh.ai)
IS0 7765-l was prepared by Technical Committee ISO/TC 61,
Plastics.
ISO 7765-1:1988
IS0 7765 consists of the
https://standards.iteh.ai/catalog/standards/sist/208c042f-73f5-4125-ba5e-
following parts, under the general title Plastics film and
sheeting - Determina tion of impact resistance by the5cb54e206348/iso-7765-1-1988
free-falling dart method :
- Part 1: Staircase methods
- Part 2: Instrumented puncture test
0 International Organization for Standardization, 1988
Printed in Switzerland
INTERNATIONAL STANDARD ISO7765-1 : 1988 (E)
Plastics film and sheeting - Determination of impact
resistance by the free-falling dart method
Part 1 I
Staircase methods
1 Scope IS0 4591 : I979, Plastics - Film and sheeting - Determination
of average thickness of a sample and average thickness
and yield of a roll by gravimetric techniques (gravimetric
1 .I This part of IS0 7765 specifies methods for the deter-
thicknessl.
mination of the energy that causes plastics film and sheet less
than I mm in thickness to fail under specified conditions of im- IS0 4593 : I979, Plastics - Film and sheeting - Determination
pact of a free-falling dart from a specified height that would of thickness by mechanical scanning.
result in failure of 50 % of the specimens tested.
iTeh STANDARD PREVIEW
1.2 Two methods of test are described. 3 Significance
(standards.iteh.ai)
3.1 Methods A and B are used to establish the mass of the
1.2.1 Method A employs a dart with a 38 mm + I mm dart causing 50 % of the specimens to fail under the conditions
diameter hemispherical head dropped from a height ISO 7765-1:1988
of specified. Data obtained by one method cannot be compared
066 m + 0,OI m. This method https://standards.iteh.ai/catalog/standards/sist/208c042f-73f5-4125-ba5e-
may be used for materials directly with those from the other method, nor with those
whose impact resistance requires masses of 5cb54e206348/iso-7765-1-1988
about 0,05 kg to obtained from tests employing different conditions of missile
about 2 kg to fracture them. velocity, missile impinging surface diameter, effective speci-
men diameter, and specimen thickness. The results obtained
with particular values of these test variables are highly depen-
1.2.2 Method B employs a dart with a 50 mm + I mm dent on the method of fabrication of the film or sheeting.
diameter hemispherical head dropped from a height of
I ,50 m + 0,OI m. Its range of applicability is from about 0,3 kg
to about 2 kg. 3.2 The results obtained by methods A and B are greatly in-
fluenced by the quality of the material under test. The con-
fidence limits of data obtained by this procedure can, therefore,
I.3 The measurement technique is the staircase method. A vary significantly, depending on the sample quality, uniformity
uniform missile mass increment is employed during testing and of gauge, die marks, contaminants, etc.
the missile weight is decreased or increased by the uniform in-
crement after test of each specimen, depending upon the result 3.3 Methods A and B have been found useful for specifi-
(failure or no failure) observed for the specimen. cation purposes. Correlation between test results and field per-
formance can usually be established.
3.4 The impact resistance of film and sheeting, while partly
2 Normative references dependent on thickness, has no simple correlation with sample
thickness. Hence, impact values cannot be normalized over a
The following standards contain provisions which, through range of thicknesses without producing misleading data as to
reference in this text, constitute provisions of this part of the actual impact resistance of the material. Data from these
IS0 7765. At the time of publication, the editions indicated methods are comparable only for sample sets that vary by no
were valid. All standards are subject to revision, and parties to more than + IO % from the nominal or average thickness of
agreements based on this part of IS0 7765 are encouraged to the specimens tested.
investigate the possibility of applying the most recent editions
of the standards listed below. Members of IEC and IS0 main-
tain registers of currently valid International Standards. 4 Definitions
IS0 291 : 1977, Plastics - Standard atmospheres for con- For the purposes of this part of IS0 7765, the following defini-
ditioning and testing. tions apply.
1
IsO7765-1:1988 E)
4.1 impact failure mass: The missile mass, estimated 5.5 Cushioning and shielding devices, to protect person-
statistically, at which 50 % of the specimens would fail in the nel and to avoid damaging the impinging surface of the dart.
specified test.
5.6 Collar, with inside diameter of approximately 7 mm and
4.2 missile mass: The total of the masses of the dart, the in- with set screw for securing collar to dart shaft.
cremental weights attached and the locking collar.
5.7 Darts, for methods A and B, with hemispherical heads,
each fitted with a 6,5 mm + 0,I mm diameter shaft at least
5 Apparatus I I5 mm long to accommodate removable incremental weights.
The mass of each dart shall be known to an accuracy of
The apparatus shall be constructed essentially as shown in
+ 0,5 %. Dart head surfaces shall be free of nicks, scratches,
figure I, using the following components:
or other irregularities. The shaft shall be attached to the centre
of the flat surface of the head with its longitudinal axis perpen-
5.1 Specimen clamp, consisting of a two-piece annular dicular to the surface. The shaft shall be made of material that
clamp having an inside diameter of I25 mm + 2 mm. The is not magnetic and shall have a steel tip 12,5 mm + 0,2 mm
lower or stationary half of the clamp shall be mounted rigidly so long at the end held by the electromagnet.
that the plane of the specimen is horizontal. The upper or
movable part of the clamp shall be designed to maintain
57.1 For method A, the dart head shall be 38 mm + I mm in
positive and plane contact with the lower part of the clamp
diameter. It may be constructed of smooth, polished
when in position. The clamps shall be provided with suitable
aluminium, phenolic plastic, or other low-density material of
means of maintaining sufficient contact to hold the test
similar hardness.
specimen firmly in place during the test.
NOTE - Pneumatically operated clamps have been successfu Ily 5.7.2 For method B, the dart head shall be 50 mm + I mm in
employed. diameter. It may be constructed of smooth, polished stainless
steel or other material of similar durability.
51.1
iTeh STANDARD PREVIEW
Rubber-like gaskets may be affixed to the specimen
contact surfaces of both clamps to provide a cushion to 5.8 Incremental weights, made of stainless steel or brass
minimize thickness variation effects. Rubber gasketing
(standards.iteh.ai)
3 mm _+ I mm thick, of 50 to 60 Shore A durometer hardness,
and cylindrical in shape. Each shall have a centre hole that
allows free fit on to a shaft of 6,5 mm * 0,I mm in diameter.
I25 mm + 2 mm in inside diameter and 150 mm + 3 mm in
outside diameter has been found satisfactory for this purpose.ISO 7765-1:1988 The thickness of each shall be adjusted to obtain the
appropriate mass within + 0,5 %. Suggested sets of weights
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5.1.2 Slippage of material greater than 0,IO mm in thickness are as follows.
5cb54e206348/iso-7765-1-1988
may be minimized or eliminated by securing crocus cloth or
50 D garnet abrasive paper to the clamps, or to the rubber-like 5.8.1 For method A, 30 mm diameter weights.
gaskets if these are used, with double-faced adhesive tape so
that the abrasive surface is in direct contact with the material to Number Mass, g
be tested. There shall be sufficient clamping force to eliminate
detectable slippage. Other means of reducing slippage such as 2 or more 5
additional clamping devices or positive clamping surfaces may 8 I5
be used provided that the test specimen is not weakened at the 8 30
inside wall of the specimen clamps and that the effective 8 60
diameter of I25 mm + 2 mm of the test specimen is not
changed. 5.8.2 For method B, 45 mm diameter weights.
52. Electromagnet, capable of supporting a 2 kg mass, for Number Mass, g
use in holding and releasing the dart assembly. It shall be equip- 2 or more I5
ped with a centring device to ensure reproducible drop and a 8 45
suitable source of electric power which may be interrupted to 8 90
energize and de-energize the electromagnet. Alternatively, the
use of air-operated or other mechanical release mechanisms is
permitted, ’ provided uniform and reproducible release is 5.8.3 Optionally, additional weights, each 120 g + 0,5 % for
obtained. method A or 180 g + 0,5 % for method B , may be constructed
for use if it is necessary to extend the missile mass beyond that
attainable when using all weights in the standard set.
5.3 Positioning device, to hold the dart at a drop height
of 066 m + 0,OI m (method A) and I,50 m + 0,OI m
(method B) from the impinging surface of the dart head to the
surface of the test specimen. The dart shall be positioned ver- 6 Test specimens
tically above the centre of the test specimen.
6.1 The test specimens shall be large enough to extend out-
5.4 Micrometer, accurate to + 0,002 5 mm in the range side the specimen clamp gaskets at all points. The specimens
from 0,002 5 mm to I mm, for measuring specimen thickness. shall be taken from the material to be tested in a manner repre-
I
2
IS0 7765-l : 1988 0
sentative of sound sampling practice, unless such sampling 8.2.4.1 Before dropping the missile on a clamped specimen,
constitutes a variable under study. The quantity of material draw a circle on the material using a marker pen in contact with
shall be sufficient to provide at least 30 test specimens. the inside wall of the upper clamp. Apply only the pressure of
the pen itself to the material.
6.2 The specimens shall be free of pinholes, wrinkles, folds,
or other obvious imperfections, unless such imperfections con- CAUTION - For safety reasons, remove the dart while
stitute variables under study. drawing the circle.
6.3 The specimen thickness shall be within + 10 % of the After the dart is dropped and prior to removing the specimen,
nominal value. draw another circle using a ball-point pen of another colour.
Distinct double lines at any point on the circumference show
that slippage has occurred.
7 Conditioning and testing atmospheres
7.1 Condition the test specimen at 23 OC + 2 OC and 8.2.4.2 If crocus cloth or sandpaper is affixed to the gaskets
50 % + - 5 % relative humidity for not less than 40 h prior to to provide greater gripping, determine slippage simply by in-
testing for materials that require conditioning. In cases of dis- specting the clamped film area after impact for evidence of
pute, the tolerances shall be + 1 OC and * 2 % relative scratch marks produced as slippage occurred.
humidity.
8.3 Staircase testing (see 1.3)
7.2 The test shall be carried out in the same a tmospheric con-
ditions as the conditioning. 8.3.1 Select method A or method B for use, as required by
the relevant material specification or as agreed between the in-
8 Procedure terested parties.
8.1 Determination of thickness 8.3.2 Measure and record the average thickness of the test
specimens in the area of impact to the nearest 0,002 5 mm
method specified in IS0 4591 or IS0 4593.
iTeh STANDARD PREVIEW
Determine the thickness of the material being tested by the (see 8.1).
NOTE - IS0 4593 is not suitable (standards.iteh.ai)
for use with
8.3.3 Select a missile mass near the expected impact failure
embossed film and
mass. Add the necessary number of incremental weights onto
sheeting.
the dart shaft and put the locking collar into place so that the
ISO 7765-1:1988 weights are held securely in place.
82. Preparation of apparatus
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5cb54e206348/iso-7765-1-1988
8.2.1 Set up the apparatus for testing by method A or by 8.3.4 Select a missile mass increment Am appropriate to the
method B. impact strength of the sample. The value chosen for Am should
be such that three to six (but at least three) missile masses will
8.2.2 Energize the electromagnet and position the specified be employed in the determination. A Am value equal to some
dart (see 5.7) vertically with the steel shaft tip inserted in the 5 % to 15 % of mf, the impact failure mass, is usually appro-
magnet adapter. Adjust the drop height (the vertical distance priate.
from the plane of a clamped specimen to the bottom surface of
the dart head) to 0,66 m + 0,Ol m for method A or to 8.3.5 Place the first test specimen over the bottom part of the
1,50 m + 0,Ol m for method B. clamp, making sure that it is uniformly flat, free of folds, and
covers the gasket at all points. Clamp in place with the top part
CAUTION - For safety reasons, remove the dart while
of the annular clamp.
making position adjustments.
8.2.3 With a trial test specimen clamped between the 83.6 Energize the electromagnet and put the dart into pos-
specimen clamps and with no added weights on the dart, de- ition. De-energize the magnet to release the dart. If the dart
energize the electromagnet to release the dart and observe the bounces off the specimen surface, catch the dart after it
point at which the dart impacts the specimen, catching the dart bounces to prevent both multiple impact with the specimen
after it bounces off the surface of the specimen. If necessary, surface and damage to the hemispherical contact surface of the
adjust the electromagnet position so that, in repeated trials, the dart resulting from impact.
dart reproducibly impacts the centre of the clamped portion of
the specimen.
8.3.7 Examine the test speci men for any evidence of slippage.
If slippage occurs, reject the results for this specimen.
8.2.4 Check the apparatus periodically to make sure specimen
slippage is not occurring during testing. If slippage occurs,
reject the results. The likelihood of slippage increases with in- 8.3.8 Examine the specimen to determine whether it has or
creasing dart mass and with increasing drop height, and is has not failed. Failure is defined as any break through the
greater with some materials than with others. Slippage may be specimen that can be observed readily by feeling or by viewing
checked conveniently during routine testing of a sample at a the specimen under back-lighting conditions. Record the
missile mass wherein both failures and non-failures are being results on a form such as that shown in figure 2, using an o to
observed. Either of the following procedures is effective. denote non-failure and an x to denote failure.
IS0 7765 : 1988 EI
8.3.9 If the first specimen fails, decrease the missile mass by where
Am. If the first specimen does not fail, increase the missile
mass by Am. Continue testing successive specimens, decreas- ni is the number of test specimens for which failure
ing or increasing the missile mass by Am between drops occurred at a mass mi,
depending upon whether the preceding specimen did or did not
fail. zi is the number of mass increments from m. to mi
(z for m. is 0);
8.3.10 After 20 specimens have been tested, count the total
number of failures Iv. If IV = 10 at this point, testing is com- k
plete. If not, complete testing as follows. N= ni (i.e. the sum of failed specimens).
c
i=l
8.3.10.1 If N < 10, continue testing additional specimens
until N = 10, then stop testing. An example of the calculation of impact failure mass is
presented in figure 2.
8.3.10.2 If N > 10, continue testing additional specimens
until the total number of non-failures (o - see 8.3.8) reaches
10, then stop testing.
10 Test report
9 Calculation 10.1 The test report shall include the following particulars:
Calculate the impact failure mass mf, in grams, as follows:
a) a reference to this part of IS0 7765;
b) a complete identification and description of the material
tested, including type, source, manufacturer’s code, prin-
cipal dimensions, and previous history;
where
iTeh STANDARD PREVIEW
c) the thickness of the material tested and the range of
m. is the lowest missile mass, in grams, at which failure
was found for the k mass steps; (standards.iteh.ai)
thicknesses of the specimens tested;
d) the test conditions and conditioning procedures, if
Am is the uniform mass increment, in grams, used; ISO 7765-1:1988
applicable;
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k
5cb54e206348/iso-7765-1-1988
e) the method used (A or 9);
A= ni Zi
c
i=l f) the impact failure mass, to the nearest 1 g.
IS077654 :I988 E)
Adjustable bracket
Centring adapter
for dart, brass, 9,5 m
centre hole
Support shaft
iP Compressed air line
0,66 m +O,Ol m - Method A
1,50 m f 0,Ol m - Method B
/-
Clamping cylinders
iTeh STANDARD PREVIEW / /
(standards.iteh.ai)
ISO 7765-1:1988
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5cb54e206348/iso-7765-1-1988 Movable clamp ring and gasket
Stationary clamp ring and gasket -
Specimen, between gaskets
Foam rubber dart stop
Key
A Steel shaft tip 6,5 mm OD by 13,5 mm long D Removable weights
B Dart shaft: 6,5 mm OD and at least 115 mm long, E Collar and screw
12,5 mm long at bottom
C Hemispherical head: Method A - 38 mm + 1 mm in diameter;
Method B - 50 mm + 1 mm in diameter
Figure 1 - Apparatus for free-falling dart impact test
(Courtesy of ASTM)
5
IS0 7765 : 1988 El
165 Y
r(r
150 0h
\,I \,I
I\ \tI4 w
a at
Ib
VI A fib LL Y w A II
135 l m w
\I \r h m v Jr
120 SIP
CL \I0L A
w \IIL
105 #\
.#
.Y I
I I I I I
0 5 30 15 20
Sequence number of test specimen
X = failure
0 = non failure
iTeh STANDARD PREVIEW
N = 10 A = 15
= 120g Am = 15g
(standards.iteh.ai)
Irno +(i -l)Ami *i I zi I *iZi I
m0
ISO 7765-1:1988
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5cb54e206348/iso-7765-1-1988
I 165 I 1 I 3 I 3 I
= 120 + 15 (I,5 -45)
= 135g
Figure 2 - Calculation of impact failure mass by the staircase procedure
UDC [678.5/.81-416 : 620.178.7
Descriptors: plastics, films, plastic sheets, tests, impact tests, test equipment.
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