EN ISO 8256:1996

SLOVENSKI STANDARD
SIST EN ISO 8256:1999
01-maj-1999
3ROLPHUQLPDWHULDOL±'RORþHYDQMHQDWH]QRXGDUQHWUGQRVWL,62
YNOMXþQRVWHKQLþQLPSRSUDYNRP
Plastics - Determination of tensile-impact strength (ISO 8256:1990, including Technical
Corrigendum 1:1991)
Kunststoffe - Bestimmung der Schlagzugzähigkeit (ISO 8256:1990, einschließlich
Technische Korrektur 1:1991)
Plastiques - Détermination de la résistance au choc-traction (ISO 8256:1992, Rectificatif
Technique 1:1991 inclus)
Ta slovenski standard je istoveten z: EN ISO 8256:1996
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 8256:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 8256:1999

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SIST EN ISO 8256:1999

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SIST EN ISO 8256:1999

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SIST EN ISO 8256:1999

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SIST EN ISO 8256:1999

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SIST EN ISO 8256:1999
IS0
INTERNATIONAL
STANDARD 8256
First edition
1990-12-15
Plastics - Determination of tensile-impact
strength
- D~ferrnination de la r&istance au d7oc-tractio\7
Plt3SficlUtS
- --
------
--. -.----s--P -v-v --
______ I__~___~ __________ --. -_____ ___ -._. -----.-_- .--- -------. .--.- _----_-_-l__________l__
Reference number
IS0 8256: 1990(E)

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SIST EN ISO 8256:1999
IS0 8256:1990(E)
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 Electrotechnicai
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an lnter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard IS0 8256 was prepared by Technical Committee
ISO/TC 6 I, Plastics.
Annexes A and B form an integral part of this international Standard.
Annex C is for information only.
0 IS0 1990
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronk or mechanical, including photocopying and microfilm, without
permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Genke 20 l Switzerland
Printed in Switzerland
ii

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SIST EN ISO 8256:1999
--
IS0 8256:1990(E)
ItiTERNATIONAL STANDARD
- Determination of tensile-impact strength
Plastics
1.5 These methods are not suitable for use as a
1 Scope
source of data for design calculations on compo-
nents. Information on the typical behaviour of a ma-
1.1 This International Standard specifies two terial can be obtained, however, by testing different
methods for the determination of the energy re-
types of test specimen prepared under different
quired to rupture test specimens of plastics under a conditions, and testing at different temperatures.
specified tensile-impact velocity. The tests can be
described as tensile tests at comparatively high
rates of straining. These methods can be used for
materials too flexible or too thin to be tested with
2 Normative references
impact tests conforming to IS0 179 and IS0 180, and
for more rigid materials. Different parameters are
The following standards contain provisions which,
specified depending on the type of test specimen
through reference in this text, constitute provisions
(see 6.1 and figure 3).
of this International Standard. At the time of publi-
cation, the editions indicated were valid. All stan-
dards are subject to revision, and parties to
1.2 These methods are used for investigating the
agreements based on this International Standard
behaviour of specified specimens undei specified
are encouraged to investigate the possibility of ap-
impact velocities, and for estimating the brittleness
plying the most recent editions of the standards in-
or the toughness of specimens within the limitations
dicated below. Members of IEC and IS0 maintain
inherent in the test conditions. The response of
registers of currently valid International Standards.
plastics to comparatively high rates of straininq is
useful to describe, for example, the behaviou; of
IS0 179:1982, Plastics .- Determination of Char-py
materials when subjected to weathering or thermal
impact strength of rigid materials.
ageing, as well as to assess their properties under
corresponding service conditions.
IS0 180: 1982, Plastics - Determination of lzod im-
pact strength of rigid materials.
c
1.3 These methods are applicable to specimens
IS0 29 1: 1977, Plastics -- Standard atmospheres for
prepared from moulding materials or to specimens
conditioning and testing.
taken from finished or semi-finished products (for
example mouldings, films, laminates or extruded or
IS0 293:1986, Plastics - Compression mouldinq test
c
cast sheets). The methods are suitable for pro-
spccimet~s of thermoplastic materials.
duction control as well as for quality control. Test
results gained on test specimens obtained from
ISO 2943975, Plastics - Injection mouldinq test
.
moulding compounds cannot be applied directly to
specimens of fhermoplastic materiak.
mouldings of any given shape, because values may
depend on the design of the mouldinq and the
\
IS0 295:1974, Plastics - Compression molilding test
moulding conditions.
specimens of thermosetfing maierials.
1.4 Results obtained by testing moulcfed speci- IS0 1268:1974, Plastics -- Preparation of glass fibre
mens of different dimensions may not necessarily reinforced, resin bonded, low-pressure laminated
be the same. Equally, specimens cut from moulded plates or- pa17eIs for test purposes.
products may not give the same results as speci-
mens of the same dimensions moulded directly from IS0 2557-4 : 1989, Plastics - Amorphous thermoplas-
the material. Results obtained by method A and tics --- Prepat-ation of test specimens with a specified
method I3 may or may not be comparable. maximum reversion -- Pat-t I: Bat-s.

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SIST EN ISO 8256:1999
IS0 8256:1990(E)
the initial potential energy in the pendulum and the
IS0 2557-2: 1986, Plastics - Amorphous ihermoplas-
energy remaining in the pendulum after breaking
tics - Preparation of test specimens with a specified
the test specimen. The energy reading shall be ac-
reversion -- Part 2, Plates.
curately corrected for friction and >ir-resistance
losses and for- scale errors.
IS0 2818:1980, Plastics - Preparation of test speci-
mens hy machining.
5.1.2 The machine shall have the characteristics
IS0 3167:1983, Plastics - Preparation and use of
shown in table 1. The frictional loss shall be period-
multipurpose test specimens.
ically checked.
In order to apply the test to the full range of
NOTE 1
3 Definitions
materials specified in 1.3, it is necessary to use more than
one machine or to use a set of interchangeable pendu-
For the purposes of this international Standard, the
lums. It is not advisable to compare results obtained with
following definitions apply.
different pendulums.
3.1 tensile-impact strength of unnotched speci-
5.1.3 The machine shall be securely fixed to a
mens: The energy absorbed in breaking an
foundation having a mass of at least 20 times that
unnotched specimen under specified conditions, re-
of the heaviest pendulum in use. It shall be adjusted
ferred to the original cross-sectional area of the
so that the orientations of the striker and supports
specimen.
are as specified in 5.2 and 5.3.
It is expressed in kilojoules per square metre
(kJm2).
5.1.4 The distance between the axis of rotation and
the centre of impact of the pendulum shall be within
3.2 tensile-impact strength of notched specimens:
+ 1 % of the distance from the axis of rotation to the
-
The energy absorbed in breaking a notched speci-
centre of the test specimen.
men under specified conditions, referred to the
original cross-sectional area of the specimen at the
5.1.5 The dial, or other indicator of the energy
notch.
consumed, shall be capable of being read to an ac-
curacy of -k I O/o of full-scale deflection.
It is expressed in kilojoules per square metre
(kJ/m*).
5.1.6 The machine shall be of the type shown
schematically in figure 1 for method A, or of the type
4 Principle
shown in figure 2 for method B.
.
The energy utilized in this test method is delivered
by a single swing of the pendulum of a tensile-
5.2 Pendulum
impact machine. The energy to fracture is deter-
mined by the kinetic energy extracted from the
5.2.1 The pendulum shall be constructed of a sin-
pendulum in the process of breaking the specimen.
gle- or multiple-membered arm holding the head, in
Corrections are made for the energy to toss or
which the greatest mass is concentrated. A rigid
bounce the crosshead.
pendulum is essential to maintain the proper clear-
ances and geometric relationships between related
The specimen is impacted at the bottom of the swing
parts and to minimize energy losses, which are al-
of the pendulum. The specimen is horizontal at rup-
ways included in the measured impact-energy
ture. One end of the specimen, at impact, is held
value.
either by the frame or the pendulum and the other
end by the crosshead. The crosshead may be either
mounted stationary on the support frame (method
5.2.2 Accurate means shall be available to deter-
A) or carried downward together with the pendulum
mine and minimize energy losses due to windage
(method 9).
and friction (see annex 9).
5 Apparatus
5.3 Crosshead
5.1 Test machine
5.3.1 The crosshead, which acts as a specimen
clamp for method A, shall be made from a material
51.1 The test machine shall be the pendulum type
which guarantees a substantially inelastic impact
and shall be of rigid construction. It shall be capable
(e.g. aluminium).
of measuring the impact energy expended in break-
The mass of the crosshead shall be selected from
ing a test specimen. The value of the impact energy
the values given in table 1. ’
shall be taken as equal to the difference between
2

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SIST EN ISO 8256:1999
IS0 8256:1990(E)
Table 1 - Characteristics of pendulum impact-testing machine
Maximum
Crosstlead massl)
T
Initial potential
Velocity at impact permissible
energy
Method A
Method B
fkictional loss
J m/s
g
g
290 2,6 to 3,2 15 & 1 or 30 * 1
15 * 1
44 2,6 to 3,2 15flor30Ifrl
095 15+1
7,5 3,4 to 4,l 30 k 1 or 60 zfr 1
03 30 * 1
3,4 to 4,-l
15,0 30 k 1 or 60 & 1
03 120+1
-
6O&lor120&1
035 120fl
OS 6Oj-d or120&1 120*1
For method A, use the lighter crosshead wherever possible.
1
I ’
5.3.2 A jig shall be used to assist in clamping the
6 Test specimens
crosshead in the specified position, at right angles
to the longitudinal axis of the specimen.
6.1 Dimensions and notches
5.4 Clamping devices/jaws
Five types of test specimen, as specified in table 2
and shown in figure3, may be used. For- method A,
5.4.1 For specimen types I, 2, 3 and 4 (see table 2
the preferred specimen types are type 1 (notched)
and figure 3), the surfaces between which the speci-
and type 3 (unnotched), but type 2, 4 or 5 may also
men is clamped shall be clamped such that there is
be used if required. For method B, the preferred
no slippage when the blow is struck. The same ap-
specimen types are type 2 and type 4.
plies to the jaw faces of the clamping device at-
tached to the frame. The clamping device shall be
The test result depends on the type of specimen
such as to ensure that it does not contribute to fail-
used and its thickness. For reproducible results, or
ure of the specimen.
in case of dispute, therefore, the type of test speci-
men and its thickness shall be agreed upon.
Jaws may have file-like serrations, and the size of
serrations shall be selected, according to experi-
Specimens are tested at their original thickness up
ence, to suit the hardness and toughness of the
to and including 4 mm.
The preferred specimen
specimen material and the thickness of the speci-
thickness is 4 mm + 0,2 mm. Within the gauge area,
men. The edges of the serrated jaws in close prox-
the thickness shallbe maintained to within a toler-
imity to the test region shall have a radius such that
ance of $- 5 %. Above 4 mm, the test methods de-
they cut across the edges of the first serrations.
scribed in this International Standard
are
inapplicable, and use shall be made of IS0 179 or
5.4.2 For specimen type 5, held only by embeddinq,
IS0 180.
a notched pair of jaws with different heights &
necessary. The pair of jaws chosen for the test shall
NOTE 2 Specimen type I can be prepared fron, the
be the one whose height is greater than the thick-
multi-purpose test specimen described in IS0 3167.
ness of the specimen but lower than 120 % of its
thickness.
6.2 Preparation
5.5 Micrometers and gauges
6.2.1 Noulding or extrusion compounds
Micrometers and gauges suitable for measuring the
dimensions of test specimens to an accuracy of
Specimens shall be prepared in accordance with the
O,Ol mm are required. For measuring the thickness
relevant material specification. When none exists,
of film and sheeting with thicknesses below 1 mm,
or when otherwise specified, specimens shall be di-
use an instrument reading to an accuracy of not less
rectly extruded, compression or injection moulded
than 5 % of the nominal thickness. In measuring the
from the material in accordance with IS0 293,
thickness of the specimen, the measuring face shall
IS0 294, IS0 295, IS0 2557-l or IS0 2557-2 as ap-
apply a load of 0,Ol MPa to 0,05 MPa.
propriate, or machined in accordance with IS0 2818
For notched specimens, see the requirements
from sheet that has been compression or injection
of 7.4. moulded from the compound.
3

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SIST EN ISO 8256:1999
IS0 8256:i 990(E)
dulum head
Base
Support for crosshead
\
Crosshead
1771 *Direction of blow
\ Ll
Vice jaw
L Test specimen
Figure I - Diagram showing relationship of pendulum to specimen clamps fsr- method A

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SIST EN ISO 8256:1999
IS0 8256:1990(E)
Pin (or other device) for holding
unsecured crosshead during downward tr;
vet
Secured
Broken specimen
Hardened striker pad
(if necessary to prevent
permanent deformation)
Unsecured crosshead
snecimen damn
i
Pendulum head
Diagram showing relationship of pendulum to specimen clamps for method B after specimen
Figure 2 --
.
rupture

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SIST EN ISO 8256:1999
IS0 8256:1990(E)
- Specimen types and dimensions and distances between supports (see also figure 3)
Table 2
Dit71ensions in rnillirnetr~es
--
Preferred value Radius of
Length, I Width, h
Specimen type
of dimension, x cwva ture, r
-----
80 & 2 10 * 0,5 6 If: 072
1’)
wkl
3 Ik 0705
2 60 & 1 IO & 0,2
20 -t 1
15 lk 03 IO * 0,5 --
3 80 & 2
15 + I
60 & 1 10 * 0,2 3 * 0,l --
4
20 * 1
8Ok 2 15 * 0,5 5 * 075
52)
-
1) Notch angle is 45” & I”, radius of notch 1 ,O mm & 0,02 mm.
mm I’ = 11 mm k 1 mm
2) For type 5: h’ = 23 mm k 2 mm r’ = 6 mm rfi 0,5
6.2.2 Sheets apex of each notch shall be within 0,02 mm of each
other. Farticular attention shall be given to the ac-
curacy of the dimension x (see table 2).
Specimens shall be machined from sheets in ac-
cordance with IS0 2818.
NOTE 3 Close tolerances have to be imposed on the
contour and the radius of the notch for most materials
6.2.3 Fibre-reinforced resins
because these factors largely determine the degree of
stress concentration at the base of the nofch during the
A panel shall be prepared from the compound in
test. The maintenance of a sharp, clean-edged cutting tool
accordance with IS0 1268, and specimens shall be
is particularly important since minor defects at the base
machined in accordance with IS0 2818.
of the notch can cause large deviations in the test results.
6.2.4 Thin films 6.3.3 Specimens with moulded-in notches may be
used if specified in the specification for the material
being tested.
For thin films, the use of multi-layer specimens is
recommended. To prepare such specimens, the
NOTE 4 Specimens with moulded-in notches generally
necessary number of layers of film shall be fixed in
do not give the same results as specimens with machined
place before stamping, e.g. by means of adhesive
notches, and allowance should be made for this difference
tapes applied over a distance of 30 mm from each
Specimens with machined
in interpreting the results.
end. The adhesive tapes are used for thin films to
notches at-e generally preferred because skin effects
hold the specimens together, at the ends, before and
and/or localized anisotropy are minimized.
after stamping. In other cases, double-faced tape
may be used between each layer of film. Film
6.3.4 For samples prepared by cuttinq with a
specimens shall be free from scratches, and each
puncher, the notch shall not be punched- but shall
layer shall be free from either tension or slackness
be machined in a second step.
relative to other layers in the specimen.
6.4 Number of test specimens
6.3 Notching of specimens (type 1)
6.4.1 Unless otherwise specified in the specifi-
6.3.1 Notches shall be machined in accordance
cation for the material being tested, a minimum of
with IS0 2818 on unnotched specimens prepared in
IO specimens shall be tested.
accordance with 6.2.
6.4.2 The impact properties of certain types of
6.3.2 The radius of the notch base shall be I,0 mm sheet material may differ depending on the direction
+ 0,02 mm, its angle 45” _+ 1” (see figure3). The
of measurement in the plane of the sheet. In such
profile of the cutting tooth (teeth) shall be such as to
cases, it is customary to prepare two groups of test
produce in the specimen, at right angles to its prin- specimens with their major axes respectively paral-
cipal axis, two notches of the contour and depth lel and perpendicular to the direction of some fea-
shown
...