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UDC 678.518: 620.172
IS0
IS0 R ECOM MEN DATI O N
R 527
PLASTICS
DETERMINATION OF TENSILE PROPERTIES
1 st EDITION
November 1966
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 527, Determination of Tensile Properties, was drawn
up by Technical Committee ISO/TC 61, Plastics, the Secretariat of which was held by the
American Standards Association, Inc. (ASA).
Work on this question by the Technical Committee began in 1953 and led, in 1960,
to the adoption of a Draft IS0 Recommendation.
This first Draft IS0 Recommendation (No. 468) was circulated to all the IS0 Member
Bodies for enquiry, in April 1960. As the results of this consultation were not considered
satisfactory, the Technical Committee presented a second Draft IS0 Recommendation,
which was circulated to all the IS0 Member Bodies in April 1964, and which was approved,
subject to a few modifications of an editorial nature, by the following Member Bodies:
Australia Hungary Spain
Austria India Sweden
Brazil Israel Switzerland
Bulgaria Japan Turkey
Canada
Korea, Rep. of United Kingdom
Chile Netherlands U.S.A.
Colombia New Zealand U.S.S.R.
Czechoslovakia Poland Yugoslavia
Denmark Portugal
Finland
Republic
Germany of South Africa
Greece Romania
Three Member Bodies opposed the approval of the Draft:
Belgium
France
Italy
The second Draft IS0 Recommendation was then submitted by correspondence to
the IS0 Council, which decided, in November 1966, to accept it as an IS0 RECOM-
MENDATION.
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IS0 I R 527 - 1966 (E)
IS0 Recommendation R 527 November 1966
PLASTICS
DETERMINATION OF TENSILE PROPERTIES
1. SCOPE
1.1 This IS0 Recommendation describes a method for determining the tensile properties of
plastics in the form of standard test specimens tested under defined conditions of pretreat-
ment, temperature, humidity and rate of separation of grips.
1.2 Three different test specimens are specified. The test specimen to be used for testing a given
material is as specified in the specification for the material. The first test specimen (Type 1,
Fig. 1) will normally be found suitable for materials, e.g. laminates based on thermosetting
resins and many rigid thermoplastic moulding materials, having moderate elongations at
break; the second (Type 2, Fig. 2) for materials, e.g. polyethylene and plasticized polyvinyl
chloride, having relatively high elongations at break and the third (Type 3, Fig. 3) for thermo-
setting moulding materials.
Different rates of separation of grips are specified to suit the different materials to which the
method can be applied. It is not possible to make a valid comparison between the results of
tensile tests on different materials if the test specimens or the rates of straining or both are
different.
C
II c,4 I I
1 -/-
QI
I
lines
\
Dimensions in millimetres
A Overall length, minimum 150
B Width at ends 20
C Length of narrow parallel portion 60 f 0.5
D Width of narrow parallel portion 10 f 0.5
E Radius, minimum 60
I: Thickness see text
G Distance between reference lines 50 f 0.5
H Initial distance between grips 115 f 5
FIG. 1. - Type 1 test specimen showing positions of reference lines (if used)
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A
cyl
J
\ LG*positions of
reference lines
Dimensions in millimetres
A Overall length, minimum
115
B Width at ends
25 f 1
C Length of narrow parallel portion
33 f 2
D Width of narrow parallel portion
6 + 0.4
O
E Small radius
14 f 1
F Large radius
25 f 2
G Distance between reference lines
25 f 1
H Initial distance between grips
80 f 5
I Thickness
see text
FIG. 2. - Cutting edges of die for Type 2 test specimen showing positions of reference lines (if used).
\ :II-%-
\- I I \&
I
I I I
I
Y
Dimensions in millimetres
Tolerance on dimensions f 5 per cent
A Overall length
110
B Width at ends
45
C Thickness at ends
6.5
D Length of narrow parallel portion
9.5
E Width of narrow parallel portion
25
F Thickness of narrow parallel portion
3.2
G
Side radius
75
H Face radius
75
J End radius
6.5
FIG. 3. - Type 3 test specimen
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II
IS0 / R 527 - 1966 (E)
2. DEFINITIONS
2.1 Tensile stress. Tensile load per unit area of minimum original cross section within the narrow
parallel portion, carried by the test specimen at any moment. It is expressed in kilogrammes-
force per square centimetre.
2.2 Percentage elongation. Increase in the distance between reference lines on the narrow parallel
portion of the test specimen, due to a tensile load, and expressed as a percentage of the
initial distance between the reference lines.
2.3 Yield point. First point on the load/extension curve at which an increase in extension occurs
without an increase in load.
NOTE. - In cases where the yield point is not well defined by the load/extension curve, it is
frequently necessary to define an offset yield point. This is done by specifying a point on the
load/extension curve where the curve departs from linearity by a specified percentage elonga-
tion or extension (see Fig. 5).
2.4 Elastic modulus. Ratio of stress to corresponding strain within the range of the greatest
stress that the material is capable of sustaining without any deviation of proportionality
of stress to strain.
It is expressed in kilogrammes-force per square centimetre.
3. SIGNIFICANCE
3.1 The tensile properties that can be measured by some or all of the procedures described in
this method include tensile stress and elongation at the yield point, tensile stress and elonga-
tion at break, maximum tensile stress and modulus of elasticity.
Materials of low ductility may not exhibit a well-defined yield point. Stress-strain curves at
several different values of temperature, humidity and straining rate usually give reasonably
reliable indications of the behaviour of materials under tensile stress.
3.2 Tensile tests may provide data for quality control, acceptance or rejection jn accordance with
the terms of specifications, research and development, engineering design and other pur-
poses. Test results cannot be considered significant for applications in which the rate of
application of stress differs considerably from those specified for this method of test. Such
applications should be considered in terms of tests such as impact, creep and fatigue.
4. APPARATUS
4.1 Testing machine. Testing machine with grips that can be separated at one or more (as
required) of the rates given in section 8.
4.1.1 Grips. Grips for holding the test specimen, one being attached to a fixed or essentially
stationary member of the machine and the other to a movable member. The grips are
self-aligning ; that is, they are attached to the fixed and movable member respectively
in such a manner that they will move freely into alignment as soon as any load is applied,
so that the long axis of the test specimen will coincide with the direction of the applied
pull through the centre line of the grip assembly. The test specimen is held in such a way
that slip relative to the grips is prevented as far as possible.
For the Type 1 and Type 2 test specimens, the grips may conveniently be of the kind
that tighten automatically under load. The grip shown in Figure 4 is suitable for the
Type 3 test specimen.
4.1.2 Load indicator. Suitable load-indicating mechanism capable of showing the total tensile
load carried by the test specimen when held by the grips. This mechanism is essentially
free from inertia lag at the specified rate of testing and indicates the load with an
accuracy of 1 per cent of the indicated value, or better.
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IS0 / R 527 - 1966 (E)
Dimensions in millimetres Tolerance on dimensions f 5 per cent
FIG. 4. - Grip for Type 3 test specimen
yield point
I
2
9
/
specified specified EXTENSION EXTENSION
offset offset
FIG. FIG. 5. 5. - - Load/extension Load/extension diagram diagram
(a) for a material for which a yield point can be determined, and
(b) for a material for which an offset yield point has to be determined.
-8-
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IS0 / R 527 - 1966 (E)
4.2 Extension indicator (when required). Suitable instrument for determining, at any time during
the test, the distance between two fixed points or reference lines located within the middle
parallel-sided part of the test specimen. It is desirable, but not essential, that this instru-
ment should automatically record this distance (or any change in it) as a function of the load
on the test specimen or of the elapsed time from the start of the test, or both. If only distance
as a function of elapsed time is recorded, load-time data are also taken. The instrument is
essentially free of inertia lag at the specified speed of testing and is accurare to f 1 per cent
of strain or better. For the measurement of modulus of elasticity the instrument is capable
of measuring the distance between the reference lines to an accuracy of & 0.1 mm.
4.2.1 When the Type 2 test specimen is used for specification or for quality control purposes,
the elongations between the reference lines at yield and at break of flexible plastics are
measured to the nearest 1 mm by any convenient means.
4.3 Micrometers. Screw micrometer reading to at least 0.02 mm for measuring the width and
thickness of the Type 1 and Type 3 test specimens.
Dial-gauge micrometer, reading to at least 0.02 mm and provided with a flat circular foot
that will apply a pressure of 0.1 to 0.3 kgf/cm2 to the test specimen, for measuring the
thickness of test specimens of non-rigid materials.
5. TEST SPECIMENS
5.1 For materials of relatively high elongation at break, the Type 2 test specimen is normally
suitable.
For testing moulding and extrusion compounds the test specimen may be moulded to shape,
in which case the thickness is normally 1 to 2 mm, or it may be cut with a knife-edged die,
with cutting edges having the form and dimensions shown in Figure 2, from sheet moulded
from the compound to a thickness of 1 to 2 mm.
For testing sheet materials the test specimen is cut from the sheet with the knife-edged die.
The thickness of the test specimen is the thickness of the sheet but is not less than 1 mm.
Reference lines, ifused, are 25 f 1 mm apart and are equidistant from the ends of the middle
1.
parallel-sided part of the test specimen as shown in Figure
5.2 For materials of lower elongation at break than those for which the Type 2 test specimen is
suitable (excepting those covered by clause 5.3), the Type 1 test specimen is normally suitable.
1.
Its form and dimensions are shown in Figure
For
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