ISO 2321:2017

INTERNATIONAL ISO
STANDARD 2321
Fourth edition
2017-08
Rubber threads — Methods of test
Fils élastiques — Méthodes d'essai
Reference number
ISO 2321:2017(E)
©
ISO 2017

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ISO 2321:2017(E)

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ISO 2321:2017(E)

Contents Page
Foreword .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Conditioning of samples or test pieces . 3
5 Count . 3
5.1 Sectional count . 3
5.2 Conventional count (size number) . 4
5.3 Apparatus . 4
5.4 Procedure . 5
5.4.1 Cutting out the test pieces . 5
5.4.2 Weighing the test pieces . 6
5.5 Expression of results . 6
6 Metric yield . 6
6.1 Procedure . 6
6.2 Expression of results . 7
7 Properties of rubber threads . 7
8 Density . 7
8.1 Principle . 7
8.2 Method . 8
8.2.1 Method A . 8
8.2.2 Method B . 8
9 Tensile strength, modulus and elongation at break . 8
9.1 Apparatus . 8
9.2 Procedure . 9
9.2.1 Test piece preparation . 9
9.2.2 Loop formation and testing . 9
9.3 Expression of results .10
10 Schwartz value (SV) .10
10.1 Apparatus .10
10.2 Procedure .10
10.3 Expression of results .11
11 Elongation under a specified load .11
11.1 Test pieces .11
11.2 Apparatus .11
11.3 Procedure .12
11.4 Expression of results .12
12 Stress retention .13
12.1 Test pieces .13
12.2 Apparatus .13
12.3 Procedure .13
12.4 Expression of results .14
12.5 Test report .14
13 Tension set .14
13.1 Test piece preparation .14
13.2 Apparatus .15
13.3 Procedure .15
13.4 Expression of results .15
14 Accelerated ageing test on rubber threads in a relaxed state .16
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ISO 2321:2017(E)

14.1 General .16
14.2 Principle .16
14.3 Test pieces .16
14.4 Apparatus .16
14.5 Procedure .16
14.6 Expression of results .16
15 Dry-heat resistance .17
15.1 General .17
15.2 Principle .17
15.3 Apparatus .17
15.4 Procedure .18
15.5 Expression of results .18
15.6 Test report .18
16 Ribbons: Degree of adhesion between threads .19
16.1 General .19
16.2 Principle .19
16.3 Apparatus .19
16.4 Test pieces .19
16.5 Procedure .19
16.6 Expression of results .20
16.7 Test report .20
17 Resistance to copper staining during laundering .20
17.1 General .20
17.2 Principle .21
17.3 Reagents.21
17.4 Apparatus and materials .21
17.5 Test pieces .22
17.6 Preparation of test pieces .22
17.6.1 General.22
17.6.2 Individual samples of textile fabric .22
17.6.3 Individual textile yarns .22
17.6.4 Multifibre fabric swatches .22
17.7 Procedure .22
17.8 Test report .23
18 Effect of washing .23
18.1 General .23
18.2 Principle .23
18.3 Apparatus .23
18.4 Standard washing solution .24
18.5 Procedure .24
18.6 Expression of results .25
18.7 Test report .25
19 Resistance to atmospheric fume staining.25
19.1 General .25
19.2 Principle .26
19.2.1 General.26
19.2.2 Method A .26
19.2.3 Method B .26
19.3 Reagents.26
19.4 Apparatus and materials .26
19.4.1 Method A .26
19.4.2 Method B .26
19.5 Test pieces .28
19.5.1 General.28
19.5.2 Method A .28
19.5.3 Method B .28
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ISO 2321:2017(E)

19.6 Procedure .28
19.6.1 Method A .28
19.6.2 Method B .28
19.7 Test report .29
Bibliography .30
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ISO 2321:2017(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.
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
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 4, Products (other than hoses).
This fourth edition cancels and replaces the third edition (ISO 2321:2006), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— Clause 3 has been added to list all the terms and definitions;
— the distance between cutting blades in Figure 1 has been added;
— the tensile testing of type A rings in Figure 2 has been added and all the figure numbers have been
updated;
— a new test, namely tension set, has been added in Clause 13;
— the clause numbers in Table 1 and Table 2 have been updated;
3
— the unit of density has been changed from megagram per cubic metre (Mg/m ) to gram per cubic
3
centimetre (g/cm ).
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INTERNATIONAL STANDARD ISO 2321:2017(E)
Rubber threads — Methods of test
1 Scope
This document specifies methods of test for determining general physical and mechanical properties of
rubber threads, as well as specific mechanical properties of such threads in contact with fabrics. Owing
to the comparatively small cross-section and the unusual conditions of service of this material, certain
special methods have been developed.
Some of the tests included in this document are not entirely suitable for threads made from certain
synthetic rubbers (e.g. urethane rubber). These tests are intended for natural or synthetic polyisoprene
rubbers.
Comparisons can only be made on new rubber threads or on those with identical processing histories.
In the interpretation of results from threads which have been subjected to spooling, fabrication or
any other process, the previous history is important, and what is known of this and of any relaxation
treatments used is intended to be reported.
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 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties
ISO 105-A02, Textiles — Tests for colour fastness — Part A02: Grey scale for assessing change in colour
ISO 105-A03, Textiles — Tests for colour fastness — Part A03: Grey scale for assessing staining
ISO 188, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 1183-2, Plastics — Methods for determining the density of non-cellular plastics — Part 2: Density
gradient column method
ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
metric yield
unstretched length, in metres, of 1 000 g of the thread
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ISO 2321:2017(E)

3.2
density
mass per unit volume of a test piece of thread measured at a standard laboratory
temperature
Note 1 to entry: It is expressed in grams per cubic centimetre.
Note 2 to entry: The standard laboratory temperatures are given in ISO 23529.
3.3
tensile strength
stress at which the thread breaks when it is stretched under specified conditions, based on the initial
cross-sectional area
2
Note 1 to entry: The value is expressed in megapascals (1MPa = 1N/mm ).
3.4
modulus at 300 % and 500 %
stress calculated with respect to the original cross-sectional area, at 300 % and 500 % elongation
2
Note 1 to entry: It is measured in megapascals (1MPa = 1N/mm ).
3.5
elongation at break
increase in length of the thread at break when it is stretched under the specified conditions, expressed
as the percentage increase of the original length
EXAMPLE A test piece, 30 mm in length which increases in length to 210 mm at break, is said to giv
...