ISO 7765-2:2022

INTERNATIONAL ISO
STANDARD 7765-2
Second edition
2022-05
Plastics film and sheeting —
Determination of impact resistance by
the free-falling dart method —
Part 2:
Instrumented puncture test
Film et feuille de plastiques — Détermination de la résistance au choc
par la méthode par chute libre de projectile —
Partie 2: Essai avec appareil de perforation
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
5 Apparatus . 5
5.1 General . 5
5.2 Test device . 5
5.2.1 General . 5
5.2.2 Energy carrier . 6
5.2.3 Striker . 7
5.2.4 Clamping device . 7
5.3 Instrument for measuring force and deflection . 9
5.3.1 General . 9
5.3.2 Force measurement sensor . 9
5.3.3 Deflection measurement system . 9
5.4 Thickness gauge . 9
6 Test specimens . 9
6.1 Sampling and preparation of test specimens . 9
6.2 Number of test specimens . 10
6.3 Conditioning of test specimens . 10
7 Procedure .10
7.1 Test atmosphere . 10
7.2 Measuring the thickness . 10
7.3 Clamping the test specimen . 10
7.4 Impact-penetration test . 10
8 Calculation and expression of results .11
9 Precision .12
10 Test report .12
Annex A (informative) General remarks .14
Bibliography .15
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 11,
Products.
This second edition cancels and replaces the first edition (ISO 7765-2:1994), which has been technically
revised.
The main changes are as follows:
— impact failure definition has been added (3.7);
— the list of clamping devices and techniques has been updated (5.2.4);
— the force measurement (5.3) has been aligned with the ISO 6603-2 method;
— the calculation clause (Clause 8) has been aligned with the ISO 6603-2 method;
— test report requirements (Clause 10) have been improved.
A list of all parts in the ISO 7765 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
The impact-penetration test described in the ISO 7765 series is used for the assessment of plastic films
and thin sheets (hereinafter referred to as films) under an impact stress applied at right angles to the
plane of the film.
ISO 7765-1 can be used if it is sufficient to characterize the impact behaviour of the film by an impact
failure energy. This document is used if a force-deformation or a force-time diagram, recorded at
practically constant velocity of the striker, is necessary for characterization of the impact behaviour.
Annex A of is for information only.
v
INTERNATIONAL STANDARD ISO 7765-2:2022(E)
Plastics film and sheeting — Determination of impact
resistance by the free-falling dart method —
Part 2:
Instrumented puncture test
1 Scope
This document specifies a test method for the determination of puncture impact properties of a plastic
film using instruments for measuring force and deflection. It is applicable if a force-deflection or force-
time diagram, recorded at nominally constant striker velocity, is required for detailed characterization
of the impact behaviour. This test method is also required when a small number of test specimens are
available, and the staircase method described in the ISO 7765-1 cannot be applied.
The test method is applicable to films of up to 1 mm thickness and makes it possible to compare
impact-penetration forces, biaxial deformabilities and energy-absorption capacities of films. Also, the
transition region between brittle and tough behaviour of the film under the conditions of testing can be
[1]
determined by varying the temperature or the penetration velocity or the relative humidity .
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 4593, Plastics — Film and sheeting — Determination of thickness by mechanical scanning
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
peak force
F
M
maximum force exerted by the striker in the direction of impact during the test
Note 1 to entry: See Figures 1 to 3.
3.2
deformation at peak force
s
M
deformation in the direction of impact at the centre of the test specimen corresponding to the peak
force (3.1)
Note 1 to entry: For materials exhibiting a peak-force plateau, the deformation is taken at the centre of the
plateau (see Figure 1).
3.3
energy to peak force
W
M
area under the force-deformation curve bounded by the origin, the peak force and the deformation at
peak force (3.2)
Note 1 to entry: See Figures 1 to 3.
3.4
total penetration energy
W
T
area under the force-deformation curve bounded by the origin, the peak force (3.1) and the deformation
at peak force (3.2)
Note 1 to entry: See Figures 1 to 3.
Note 2 to entry: If the force-deformation diagram as measured during the test is influenced strongly by dynamic
resonance effects, a mean curve may be used to obtain the values of the parameters defined in 3.1 to 3.4. This,
however, is seldom the case when plastic film is tested
Note 3 to entry: In contrast to the instrumented puncture test applied to test specimens made of brittle plastic
(see ISO 6603-2), the force-deformation diagram of this test applied to film and sheeting frequently shows a clear
point of first failure (failure point) indicated by a sharp drop in the force. If this is the case, and if the interested
parties agree to use this point as a characteristic criterion, the following additional definitions may be used.
3.5
failure force
F
F
force exerted by the striker in the direction of impact, measured at the failure point
Note 1 to entry: See Figures 1 and 2.
3.6
failure deformation
s
F
deformation in the direction of impact at the centre of the test specimen, measured at the failure, point
Note 1 to entry: See Figures 1 and 2.
3.6.1
failure energy
W
F
area under the force deformation curve bounded by the origin, the failure force (3.5) and the failure
deformation (3.6)
Note 1 to entry: See Figures 1 and 2.
Note 2 to entry: When comparing films of slightly different thicknesses, it is advisable to relate F , F , W and
M F M
W to the thickness d of the specimen. Though the normalized values F /d, F /d, W /d and W /d do not allow a
F M F M F
physically exact comparison between film specimens of different materials, the thickness dependence of these
normalized values is negligible for similar materials (those with the same amount of crystallinity and the same
orientation) provided the thicknesses do not differ by more than a factor of 1,5.
3.7
impact failure
mechanical behaviour of the material under test which may be either one of the following types:
a) ductile. If a clear failure point is available and parts agree, the ductile behaviour can be described
in terms of “Very tough” (see Figure 1 as example) and “Tough” (see Figure 2 as example)
b) brittle
Key
Y force
X deformation
Figure 1 — Force-deformation diagram for very tough materials (schematic)
Key
Y force
X deformation
Figure 2 — Force-deformation diagram for tough materials (schematic)
Key
Y force
X deformation
Figure 3 — Force-deformation diagram for brittle materials (schematic)
4 Principle
The test specimen is penetrated normal to its plane by a striker at a nominally uniform velocity. The
resulting force-deformation or force-time diagram is electronically recorded. The test specimen is
firmly clamped during the test.
The force-deformation diagram obtained in these tests shows several features of the material's
behaviour under impact. For example, the fracture may be “brittle”, “ductile” – “tough” or “very tough”
– or characterized by initial damage or by crack initiation and propagation. In addition, dynamic effects
may be present, such as load-cell/indenter resonance, specimen resonance and initial contact/inertia
peaks (see Figures 1 to 3).
In all cases, care shall be exercised in analysing these features because the operative mechanism and
the trains of inference are not yet fully established, and are the subject of continuing research.
The test results are comparable only if the conditions for preparation of specimens, their thickness
and surfaces, and the test conditions are identical. Comprehensive evaluation of the reaction to impact
stress requires that the determinations are made as functions of deformation rate and temperature for
different material variables, such as crystallinity and moisture content.
5 Apparatus
5.1 General
The apparatus consists of a mechanical test device for applying the test force, instruments for
measuring the force and the deformation produced, and a thickness gauge.
5.2 Test device
5.2.1 General
The essential components of the test device are the energy carrier (normally a falling mass, but a
pneumatically, hydraulically or spring-driven mass or a pendulum impact-testing device may also be
used), the striker, and the clamping device consisting of the test specimen support and the clamping
ring (see Figures 4 and 5).
The apparatus shall permit the test specimen to be punctured at the centre at a nominally constant
velocity, perpendicular to the specimen surface. The force exerted on the test specimen in the direction
of impact and the deformation of the specimen in the direction of impact shall be measurable or
derivable (see Figure 4). Equipment suitable for this are falling dart machines, pendulums long enough
for the penetration path to be regarded as approximately straight, or high-speed tensile-testing
machines with suitable attachments.
Key
1 test specimen
2 hemispherical striker, diameter D
3 load cell (preferred position)
4 shaft
5 clamping ri
...