ISO 7725:2020
(Main)Rubber and rubber products — Determination of chlorine and bromine content
Rubber and rubber products — Determination of chlorine and bromine content
This document specifies methods for the determination of chlorine and/or bromine present in raw rubber as well as vulcanized or unvulcanized rubber compounds. The methods are applicable to natural rubbers and to the following synthetic rubbers: isoprene, styrene-butadiene, butadiene, butyl, halogenated butyl, nitrile, ethylene-propylene, chloroprene and epichlorohydrin.
Caoutchouc et produits à base de caoutchouc — Détermination de la teneur en brome et en chlore
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INTERNATIONAL ISO
STANDARD 7725
Second edition
2020-01
Rubber and rubber products —
Determination of chlorine and
bromine content
Caoutchouc et produits à base de caoutchouc — Détermination de la
teneur en brome et en chlore
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Sample preparation . 2
5.1 Sampling . 2
5.2 Sample solutions . 2
6 Method A — Ion chromatography . 2
6.1 Reagents. 2
6.2 Apparatus . 3
6.3 Determination . 3
6.3.1 Setting up the ion chromatograph . 3
6.3.2 Preparation of the calibration curve . 3
6.3.3 Measuring blank solutions and sample solutions . 3
6.4 Calculation . 4
7 Method B — Potentiometric titration . 4
7.1 Reagents. 4
7.2 Apparatus . 5
7.3 Determination . 5
7.4 Calculation . 6
8 Precision . 7
9 Test report . 7
Annex A (normative) Preparation of sample solutions by the tubular furnace combustion
method . 8
Annex B (normative) Preparation of sample solutions by the oxygen combustion flask method .11
Annex C (normative) Preparation of sample solutions by the oxygen combustion bomb method .14
Annex D (informative) Conditions for ion chromatography .16
Annex E (informative) Precision results from an interlaboratory test programme .18
Bibliography .20
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 of 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 www .iso .org/
iso/ foreword .html.
The committee responsible for this document is ISO/TC 45, Rubber and rubber products, Subcommittee
SC 2, Testing and analysis.
This second edition cancels and replaces the first edition (ISO 7725:1991), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the ion chromatography method has been added in Clause 6;
— the titration procedure has been improved in Clause 7;
— the tubular furnace combustion method for sample preparation has been added in Annex A;
— the oxygen combustion flask method for sample preparation has been improved in Annex B;
— the oxygen combustion bomb method for sample preparation has been added in Annex C;
— mercury nitrate and hydrazine are no longer used due to their hazardous properties.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
Introduction
The two test methods in this document for quantitative analysis can be used for any type of rubbers
(i.e. raw rubber, vulcanized rubber or unvulcanized rubber) containing chlorine and/or bromine in any
form of existence, such as an element of polymer chain, chemical additives or a part of contaminations.
Three combustion methods are given for preparation of sample solution, i.e. tubular furnace
combustion method, oxygen combustion flask method and oxygen combustion bomb method. After
sample solutions are prepared, a content determination procedure, i.e. either ion chromatography or
potentiometric titration, follows. The most convenient and efficient method from the testing time and
safeness points of view, is the combination of tubular furnace combustion and ion chromatography, as
ion chromatography is widely used in quality control of polymer/rubber products or in environmental
analysis.
INTERNATIONAL STANDARD ISO 7725:2020(E)
Rubber and rubber products — Determination of chlorine
and bromine content
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document 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
determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document might involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies methods for the determination of chlorine and/or bromine present in raw
rubber as well as vulcanized or unvulcanized rubber compounds.
The methods are applicable to natural rubbers and to the following synthetic rubbers: isoprene,
styrene-butadiene, butadiene, butyl, halogenated butyl, nitrile, ethylene-propylene, chloroprene and
epichlorohydrin.
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 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4661-2, Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Principle
A sample solution is obtained by combustion of a test piece either burnt in a tubular furnace with
a stream of oxygen-containing gas and passed into a prepared solution or burnt in an oxygenic
atmosphere in a flask or a bomb which contains a solution to absorb the combustion gas. The sample
solution is then analysed by ion chromatography (method A) or potentiometric titration (method B) to
determine the content of chlorine and/or bromine in a sample.
For rubber samples of very low halogen content, method A is preferable since the inflection point might
not be obtained by method B.
5 Sample preparation
5.1 Sampling
For raw rubber, carry out sampling in accordance with ISO 1795.
For rubber compounds, carry out sampling in accordance with ISO 4661-2.
NOTE Chlorine and bromine contained in additives or contaminants can be detected by these sampling
methods, unless previously removed by extraction.
5.2 Sample solutions
To prepare sample solutions by the tubular furnace combustion method, follow the method specified in
Annex A. Repeat the procedure to create two solutions for each sample.
To prepare sample solutions by the oxygen combustion flask method, follow the method specified in
Annex B. Repeat the procedure to create two solutions for each sample.
To prepare sample solutions by the oxygen combustion bomb method, follow the method specified in
Annex C. Repeat the procedure to create two solutions for each sample.
If incomplete combustion, such as soot generation during combustion, is expected by the oxygen
combustion flask method, it is preferable to use
...
INTERNATIONAL ISO
STANDARD 7725
Second edition
2020-01
Rubber and rubber products —
Determination of chlorine and
bromine content
Caoutchouc et produits à base de caoutchouc — Détermination de la
teneur en brome et en chlore
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Sample preparation . 2
5.1 Sampling . 2
5.2 Sample solutions . 2
6 Method A — Ion chromatography . 2
6.1 Reagents. 2
6.2 Apparatus . 3
6.3 Determination . 3
6.3.1 Setting up the ion chromatograph . 3
6.3.2 Preparation of the calibration curve . 3
6.3.3 Measuring blank solutions and sample solutions . 3
6.4 Calculation . 4
7 Method B — Potentiometric titration . 4
7.1 Reagents. 4
7.2 Apparatus . 5
7.3 Determination . 5
7.4 Calculation . 6
8 Precision . 7
9 Test report . 7
Annex A (normative) Preparation of sample solutions by the tubular furnace combustion
method . 8
Annex B (normative) Preparation of sample solutions by the oxygen combustion flask method .11
Annex C (normative) Preparation of sample solutions by the oxygen combustion bomb method .14
Annex D (informative) Conditions for ion chromatography .16
Annex E (informative) Precision results from an interlaboratory test programme .18
Bibliography .20
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 of 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 www .iso .org/
iso/ foreword .html.
The committee responsible for this document is ISO/TC 45, Rubber and rubber products, Subcommittee
SC 2, Testing and analysis.
This second edition cancels and replaces the first edition (ISO 7725:1991), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the ion chromatography method has been added in Clause 6;
— the titration procedure has been improved in Clause 7;
— the tubular furnace combustion method for sample preparation has been added in Annex A;
— the oxygen combustion flask method for sample preparation has been improved in Annex B;
— the oxygen combustion bomb method for sample preparation has been added in Annex C;
— mercury nitrate and hydrazine are no longer used due to their hazardous properties.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
Introduction
The two test methods in this document for quantitative analysis can be used for any type of rubbers
(i.e. raw rubber, vulcanized rubber or unvulcanized rubber) containing chlorine and/or bromine in any
form of existence, such as an element of polymer chain, chemical additives or a part of contaminations.
Three combustion methods are given for preparation of sample solution, i.e. tubular furnace
combustion method, oxygen combustion flask method and oxygen combustion bomb method. After
sample solutions are prepared, a content determination procedure, i.e. either ion chromatography or
potentiometric titration, follows. The most convenient and efficient method from the testing time and
safeness points of view, is the combination of tubular furnace combustion and ion chromatography, as
ion chromatography is widely used in quality control of polymer/rubber products or in environmental
analysis.
INTERNATIONAL STANDARD ISO 7725:2020(E)
Rubber and rubber products — Determination of chlorine
and bromine content
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document 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
determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document might involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies methods for the determination of chlorine and/or bromine present in raw
rubber as well as vulcanized or unvulcanized rubber compounds.
The methods are applicable to natural rubbers and to the following synthetic rubbers: isoprene,
styrene-butadiene, butadiene, butyl, halogenated butyl, nitrile, ethylene-propylene, chloroprene and
epichlorohydrin.
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 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4661-2, Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Principle
A sample solution is obtained by combustion of a test piece either burnt in a tubular furnace with
a stream of oxygen-containing gas and passed into a prepared solution or burnt in an oxygenic
atmosphere in a flask or a bomb which contains a solution to absorb the combustion gas. The sample
solution is then analysed by ion chromatography (method A) or potentiometric titration (method B) to
determine the content of chlorine and/or bromine in a sample.
For rubber samples of very low halogen content, method A is preferable since the inflection point might
not be obtained by method B.
5 Sample preparation
5.1 Sampling
For raw rubber, carry out sampling in accordance with ISO 1795.
For rubber compounds, carry out sampling in accordance with ISO 4661-2.
NOTE Chlorine and bromine contained in additives or contaminants can be detected by these sampling
methods, unless previously removed by extraction.
5.2 Sample solutions
To prepare sample solutions by the tubular furnace combustion method, follow the method specified in
Annex A. Repeat the procedure to create two solutions for each sample.
To prepare sample solutions by the oxygen combustion flask method, follow the method specified in
Annex B. Repeat the procedure to create two solutions for each sample.
To prepare sample solutions by the oxygen combustion bomb method, follow the method specified in
Annex C. Repeat the procedure to create two solutions for each sample.
If incomplete combustion, such as soot generation during combustion, is expected by the oxygen
combustion flask method, it is preferable to use
...
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