EN ISO 1421:1998
(Main)Rubber- or plastics-coated fabrics - Determination of tensile strength and elongation at break (ISO 1421:1998)
Rubber- or plastics-coated fabrics - Determination of tensile strength and elongation at break (ISO 1421:1998)
This standard specifies a method for determination of breaking strength and elongation at break of fabrics coated with rubber or plastics.
Mit Kautschuk oder Kunststoffe beschichtete Textilien - Bestimmung der Zugfestigkeit und der Bruchdehnung (ISO 1421:1998)
Diese Internationale Norm beschreibt zwei Verfahren zur Bestimmung der Zugfestigkeit von Textilien, die mit Kautschuk oder Kunststoff beschichtet sind: - Verfahren 1: das Streifen-Pru(fverfahren, mit dem Zugfestigkeit und Bruchdehnung bestimmt werden; - Verfahren 2: das Grab-Pru(fverfahren, mit dem die Zugfestigkeit bestimmt wird. Beide Verfahren gelten sowohl fu(r Probeko(rper, die sich im Gleichgewicht mit fu(r die Pru(fung festgelegten Normalklimaten befinden als auch fu(r Probeko(rper fu(r den Naß-Zugversuch.
Supports textiles revêtus de caoutchouc ou de plastique - Détermination de la force de rupture et de l'allongement à la rupture (ISO 1421:1998)
Gumirane ali plastificirane tekstilije - Ugotavljanje natezne trdnosti in pretržnega raztezka (ISO 1421:1998)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-1999
Gumirane ali plastificirane tekstilije - Ugotavljanje natezne trdnosti in pretržnega
raztezka (ISO 1421:1998)
Rubber- or plastics-coated fabrics - Determination of tensile strength and elongation at
break (ISO 1421:1998)
Mit Kautschuk oder Kunststoffe beschichtete Textilien - Bestimmung der Zugfestigkeit
und der Bruchdehnung (ISO 1421:1998)
Supports textiles revetus de caoutchouc ou de plastique - Détermination de la force de
rupture et de l'allongement a la rupture (ISO 1421:1998)
Ta slovenski standard je istoveten z: EN ISO 1421:1998
ICS:
59.080.40 3RYUãLQVNRSUHYOHþHQH Coated fabrics
WHNVWLOLMH
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 1421
Second edition
1998-06-15
Rubber- or plastics-coated fabrics —
Determination of tensile strength and
elongation at break
Supports textiles revêtus de caoutchouc ou de plastique — Détermination
de la force de rupture et de l'allongement à la rupture
A
Reference number
ISO 1421:1998(E)
ISO 1421:1998(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.
International Standard ISO 1421 was prepared by Technical Committee
ISO/TC 45, Rubber and rubber products.
This second edition cancels and replaces the first edition (ISO 1421:1977),
which has been technically revised.
© ISO 1998
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
ii
©
INTERNATIONAL STANDARD ISO ISO 1421:1998(E)
Rubber- or plastics-coated fabrics — Determination
of tensile strength and elongation at break
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
1.1 This International Standard describes two methods for the determination of the tensile strength of fabrics
coated with rubber or plastics:
Method 1 — the strip test method, which is a method for the determination of tensile strength and elongation at
break;
Method 2 — the grab test method, which is a method for the determination of tensile strength only.
1.2 The methods apply to test pieces in equilibrium with specific standard atmospheres for testing, and to wet
test pieces.
1.3 Both methods require the use of a constant rate of extension (CRE) tensile-testing machine.
2 Normative references
The following standards contains 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 2231:1989, Rubber- or plastics-coated fabrics — Standard atmospheres for conditioning and testing.
ISO 2286-2:1998, Rubber- or plastics-coated fabrics — Determination of roll characteristics — Part 2: Methods for
determination of total mass per unit area, mass per unit area of coating and mass per unit area of substrate.
ISO 7500-1:1986, Metallic materials — Verification of static uniaxial testing machines — Part 1: Tensile testing
machines.
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ISO
ISO 1421:1998(E)
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 maximum force: The maximum force recorded in extending the test piece to breaking point (see figure 1).
3.2 elongation; extension (E): The increase in length of a test piece, expressed in units of length, e.g. cm
or mm.
3.3 percentage elongation: The elongation expressed as a percentage of the nominal gauge length.
3.4 force at break: The tensile force recorded at the moment of break (see figure 2).
NOTE — Figure 3 corresponds to the rupture of one of the elements constituting the coated fabric. Typical examples are:
a) a "rigid" polymer layer on an extensible fabric: rupture of the polymer layer;
b) a very extensible, thick polymer layer on a weak, less extensible fabric or nonwoven: rupture of the woven fabric or of the
nonwoven.
3.5 elongation at break: The elongation of a test piece corresponding to the force at the breaking point (see
figure 2), usually expressed as a percentage of the nominal gauge length.
3.6 nominal gauge length: The length of a test piece under a specified pre-tension, measured from nip to nip
of the jaws of the holding clamps with the clamps in their starting position.
NOTE — The nominal gauge length is also referred to as the initial gauge length.
3.7 elongation at maximum force: The elongation of a test piece produced by the maximum force (see
figure 1).
3.8 constant rate of extension (CRE): A means of conducting a tensile test in which the rate of increase in
the length of the test piece is uniform with time.
NOTE — The rate of increase of the force is dependent upon the extension characteristics of the test piece.
3.9 strip test: A tensile strength test in which the full width of the test piece is gripped in the jaws.
3.10 grab test: A tensile strength test in which only the central part of the width of the test piece is gripped in the
jaws.
4 Principle
A test piece is extended at a constant rate of extension until it breaks. For method 1 (clause 7), the maximum force
and the elongation at maximum force and, if required, the force at break and the elongation at break are determined.
For method 2 (clause 8), the maximum force only is determined.
5 Apparatus
5.1 Constant rate of extension (CRE) tensile testing machine, having the following general characteristics:
The machine shall be provided with means for reading and recording both the force applied to the test piece in
stretching it to the breaking point and the corresponding extension of the test piece. It shall be provided with a
strength indicator having several scales in order to ensure that the rupture of each test piece is obtained with a
strength of 15 % to 85 % of the maximum of the scale used. Under conditions of use, the accuracy of the apparatus
shall be class 1 as defined in ISO 7500-1. The error of the indicated or recorded maximum force at any point in the
range in which the machine is used shall not exceed ±1 %, and the error of the indicated or recorded jaw separation
shall not exceed 1 mm.
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ISO 1421:1998(E)
After the first 2 s of the test, the rate of increase in the distance between the clamps shall be uniform to within 5 %.
If the force and elongation are recorded by means of data acquisition boards and software, the frequency of data
−1
collection shall be at least 8 s .
5.2 Clamping device, with the central point of the two jaws of the machine in the line of pull, the front edges at
right angles to the line of pull and their clamping faces in the same plane. The jaws shall be capable of holding the
test piece without allowing it to slip. They shall be designed so that they do not damage the test piece or reduce its
strength. Smooth, flat or engraved corrugated jaws can be used for clamping. Using suitable packing materials in
the jaws, e.g. paper, leather, plastics or rubber, avoids difficulties in clamping in many cases.
When tests are carried out and the test pieces either break at the jaws or tend to slip, the results may often be
discarded. In order to obtain legitimate results by avoiding jaw breaks and the effect of slippage, the use of capstan
jaws or any other self-locking device can be a suitable alternative to ordinary flat jaws. When information on strain is
required, elongation measurements are made by means of an extensometer which follows the movements of two
reference points on the test piece. The use of such jaws and an extensometer shall be reported in the test report
(see 7.4, item k).
For the strip test method, the jaws shall be not less than the width of the test piece and should preferably have a
width of at least 60 mm.
For the grab test method, the dimensions of one of the jaws of each clamp shall be 25 mm ± 0,5 mm by
25 mm ± 0,5 mm. The other jaw of each clamp shall be at least as wide as the one to which it is attached and
should preferably be 50 mm wide.
5.3 Equipment for cutting test pieces and fraying them down to the required width.
5.4 Equipment in which the test pieces can be immersed in water prior to wet testing.
5.5 Distilled or deionized water, for wetting out the test pieces.
5.6 Wetting agent or surfactant.
6 Atmosphere for conditioning and testing
The atmosphere used for conditioning and testing shall be one of those specified in ISO 2231. The sample shall be
conditioned for not less than 24 h.
NOTE — If the test results are to be representative of the properties of the coated fabric at the time of manufacturing and
distribution, the tests must be carried out no longer than 3 months after the date of manufacture.
7 Method 1: strip test method
7.1 Sampling and preparation of test pieces
From each sample, cut two sets of test pieces, one set in the longitudinal direction and the other in the transverse
direction. Each set shall consist of not less than five test pieces. If, by agreement between the interested parties,
a higher degree of precision is required, test more test pieces.
Select the test pieces from the full usable width and length of the sample in accordance with ISO 2286-2. An
example of how test pieces may be cut out is given in figure 4.
Each test piece shall be 50 mm ± 0,5 mm wide and of sufficient length to allow a distance of 200 mm ± 1 mm
between the jaws of the test machine. If the elongation exceeds 75 %, reduce the length to 100 mm ± 1 mm.
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ISO 1421:1998(E)
If there is a woven support, take a wider strip and reduce the width to 50 mm ± 0,5 mm by fraying if possible. Should
fraying not be possible, cut the test pieces in the direction of testing as exactly as possible along a thread.
If it is not possible to cut exactly along a thread because of distortion of the threads or the presence of an invisible
support, use another test method, for example method 2.
If there is a knitted support, cut the test pieces to their final dimensions by following a wale or course. If it is not
possible to cut a suitable test piece because of distortion of the threads or the presence of an invisible support, use
another test method, for example method 2.
If there is a nonwoven support such as felt, cut rectangular test pieces in the longitudinal and transverse directions
with tidy edges.
If tests are to be made on wet test pieces, completely immerse these for 1 h, or longer if specified, at room
temperature in an aqueous solution of a wetting agent of concentration not more than 0,1 % (V/V). Rinse thoroughly
in water and test within 1 min of removal from the water.
7.2 Procedure
7.2.1 Mounting the test piece in place
7.2.1.1 General
Set the jaws of the test machine 200 mm ± 1 mm apart, or 100 mm ± 1 mm apart if more appropriate. Clamp a test
piece in the stationary jaws so that its longitudinal axis passes through the centre of the front edge of each jaw.
Test pieces can be mounted under pre-tension or in the slack condition. When test pieces are mounted under
pre-tension, check that the pre-tension does not produce an elongation greater than 5 %. If these conditions cannot
be met, mount the test piece in the slack condition.
7.2.1.2 Pre-tension setting
Apply the appropriate pre-tension from the following:
a) 2 N for coated fabrics up to and including 200 g/m ;
2 2
b) 5 N for coated fabrics over 200 g/m and up to and including 500 g/m ;
c) 10 N for coated fabrics over 500 g/m .
7.2.1.3 Slack mounting
When test pieces are mounted in the slack condition, the starting point of the curve corresponds to a 0,5 N
pre-tension force. Add the corresponding elongation to the initial gauge length.
7.2.2 Operation
Engage any device for reading the breaking strength and elongation. Set the moving clamp in motion, at a constant
rate of 100 mm/min ± 10 mm/min unless otherwise agreed between the interested parties, and extend the test piece
to the breaking point. Repeat the procedure for each test piece.
7.2.3 Slippage
Disregard any test results where the test piece slips asymmetrically or slips by more than 2 mm.
When results are discarded, repeat the test on a replacement test piece taken, if practicable, from the same part of
the sample as the discarded test piece.
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ISO 1421:1998(E)
7.2.4 Jaw breaks
Disregard any test results where the test piece breaks within 5 mm of the face of a jaw.
When results are discarded, repeat the test on a replacement test pi
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