ISO 132:1999
(Main)Rubber, vulcanized or thermoplastic — Determination of flex cracking and crack growth (De Mattia)
Rubber, vulcanized or thermoplastic — Determination of flex cracking and crack growth (De Mattia)
Caoutchouc vulcanisé ou thermoplastique — Détermination de la résistance au développement d'une craquelure (De Mattia)
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 132
Third edition
1999-03-15
Rubber, vulcanized or thermoplastic —
Determination of flex cracking and crack
growth (De Mattia)
Caoutchouc vulcanisé ou thermoplastique — Détermination de la résistance
au développement d'une craquelure (De Mattia)
A Reference number
ISO 132:1999(E)
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ISO 132:1999(E)
Content
1 Scope .1
2 Normative references .1
3 Apparatus .1
4 Test pieces .2
4.1 Shape, dimensions and preparation.2
4.2 Preparation of test pieces for cut growth measurement .3
4.3 Time interval between vulcanization and testing .3
4.4 Conditioning.3
4.5 Number of test pieces .4
5 Test conditions .5
5.1 Temperature .5
5.2 Humidity.5
6 Procedure .5
6.1 General.5
6.2 Determination of flex cracking .5
6.3 Determination of crack growth.5
7 Expression of results .6
7.1 Determination of flex cracking .6
7.2 Determination of crack growth.6
8 Precision.7
9 Test report .7
© ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
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ISO ISO 132:1999(E)
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 through ISO 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, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO 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 voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
ISO 132 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2,
Physical and degradation tests.
This third edition cancels and replaces the second edition (ISO 132:1983) and ISO 133:1983, of which it constitutes
a technical revision.
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ISO 132:1999(E) ISO
Introduction
Repeated bending or flexing of a rubber causes cracks to develop in that part of the surface where tension stress is
set up during flexing or, if this part of the surface contains a crack, causes this crack to extend in a direction
perpendicular to the stress. Certain soft vulcanizates, for instance those prepared from styrene-butadiene rubber,
show marked resistance to crack initiation, but it is possible for these vulcanizates to have a low resistance to
growth (propagation) of cracks. It is important, therefore, to measure both the resistance to crack initiation by flexing
and the resistance to crack propagation.
The method is suitable for rubbers that have reasonably stable stress-strain properties, at least after a period of
cycling, and do not show undue stress softening or set, or highly viscous behaviour. The results obtained for some
thermoplastic rubbers should be treated with caution if the elongation at yield is below, or close to, the maximum
strain imposed during the test.
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INTERNATIONAL STANDARD ISO ISO 132:1999(E)
Rubber, vulcanized or thermoplastic — Determination
of flex cracking and crack growth (De Mattia)
WARNING — Persons using this International Standard should be familiar with normal laboratory practice.
This standard does not purport to address all of the safety problems, if any, associated with its use. It is
the responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any national regulatory conditions.
1 Scope
This International Standard specifies a method of test intended for use in comparing the resistance of rubbers to the
formation and growth of cracks, when subjected to repeated flexing on the De Mattia type machine. For
determination of crack growth, an artificial cut is made in the test piece to initiate cut growth.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 471:1995, Rubber — Temperatures, humidities and times for conditioning and testing.
ISO 3383:1985, Rubber — General directions for achieving elevated or subnormal temperatures for test purposes.
ISO 4661-1:1993, Rubber, vulcanized or thermoplastic — Preparation of samples and test pieces — Part 1:
Physical tests.
3 Apparatus
3.1 De Mattia type machine.
The essential features of the De Mattia type machine are as follows:
Stationary parts, provided with grips for holding one end of each of the test pieces in a fixed position, and similar but
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reciprocating parts for holding the other end of each of the test pieces. The travel is (57 ) mm and is such that
0
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the maximum distance between each set of opposing grips is (75 ) mm (see figure 1).
0
The reciprocating parts are so arranged that their motion is straight and in the direction of, and in the same plane
as, the common centreline of each opposing pair of grips. The planes of the gripping surfaces of each opposing pair
of grips remain parallel throughout the motion.
The eccentric which actuates the reciprocating parts is driven by a constant-speed motor to give 5,00 Hz ± 0,17 Hz,
with sufficient power to flex at least six, and preferably twelve, test pieces at one test. The grips hold the test pieces
firmly, without undue compression, and enable individual adjustment to be made to the test pieces to ensure
accurate insertion.
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ISO
ISO 132:1999(E)
Dimensions in millimetres
Key
1 Upper grip
2 Travel
3 Lower grip
Figure 1 — De Mattia type machine
It is useful to arrange the test pieces in two equal groups, so that one group is being flexed while the other group is
being straightened, thus reducing the vibration in the machine.
For testing at elevated or subnormal temperatures, the machine may be enclosed in a chamber with temperature
control near the centre of the test piece to ± 2 °C, if necessary, by using an air circulator.
3.2 Piercing tool and suitable jig, for piercing the test pieces (see 4.2).
4 Test pieces
4.1 Shape, dimensions and preparation
Each test piece shall be a strip with a moulded groove, as shown in figure 2. The strips may be moulded individually
in a multiple-cavity mould or may be cut from a wide slab having a moulded groove.
The groove in the test piece shall have a smooth surface and be free from irregularities from which cracks may start
prematu
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