Rubber — Analysis by pyrolytic gas-chromatographic methods — Part 1: Identification of polymers (single polymers and polymer blends)

This document specifies a method for the identification of polymers, or blends of polymers, in raw rubbers and in vulcanized or unvulcanized compounds from pyrograms (pyrolysis-gas chromatographic patterns) obtained under the same conditions. This allows qualitative identification of single rubbers or blends, with exceptions discussed below. This document is not intended for quantitative analysis. The method applies first and foremost to single polymers. When the pyrogram indicates a characteristic hydrocarbon, the method is also applicable to blends. For details, see Clause 5. The method can be also applicable to other types of polymer when verified by the analyst in each particular case. NOTE The use of this document pre-supposes sufficient working knowledge of the principles and techniques of gas chromatography to enable the analyst to carry out the operations described and to interpret the results correctly.

Caoutchouc — Méthodes d'analyse par pyrolyse et chromatographie en phase gazeuse — Partie 1: Identification des polymères (un seul polymère ou un mélange de polymères)

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Published
Publication Date
10-Feb-2020
Current Stage
6060 - International Standard published
Start Date
11-Feb-2020
Completion Date
11-Feb-2020
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INTERNATIONAL ISO
STANDARD 7270-1
Second edition
2020-02
Rubber — Analysis by pyrolytic gas-
chromatographic methods —
Part 1:
Identification of polymers (single
polymers and polymer blends)
Caoutchouc — Méthodes d'analyse par pyrolyse et chromatographie
en phase gazeuse —
Partie 1: Identification des polymères (un seul polymère ou un
mélange de polymères)
Reference number
ISO 7270-1:2020(E)
ISO 2020
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ISO 7270-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© 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.
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Email: copyright@iso.org
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Published in Switzerland
ii © ISO 2020 – All rights reserved
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ISO 7270-1:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Single polymers and blends ...................................................................................................................................................................... 2

5.1 General ........................................................................................................................................................................................................... 2

5.2 Group M ......................................................................................................................................................................................................... 2

5.3 Group O .......................................................................................................................................................................................................... 2

5.4 Group Q .......................................................................................................................................................................................................... 2

5.5 Group R .......................................................................................................................................................................................................... 2

5.6 Blends ............................................................................................................................................................................................................. 3

6 Reagents ........................................................................................................................................................................................................................ 3

7 Apparatus ..................................................................................................................................................................................................................... 3

7.1 Extraction apparatus ......................................................................................................................................................................... 3

7.2 Pyrolysis/chromatography system ....................................................................................................................................... 3

7.2.1 General...................................................................................................................................................................................... 3

7.2.2 Pyrolysis device ................................................................................................................................................................ 4

7.2.3 Gas chromatograph ....................................................................................................................................................... 4

7.2.4 Chromatographic columns ...................................................................................................................................... 4

7.2.5 Data-handling equipment ........................................................................................................................................ 4

8 Procedure..................................................................................................................................................................................................................... 4

9 Interpretation of results ............................................................................................................................................................................... 5

10 Test report ................................................................................................................................................................................................................... 5

© ISO 2020 – All rights reserved iii
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ISO 7270-1:2020(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 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.

This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,

Subcommittee SC 2, Testing and analysis.

This second edition cancels and replaces the first edition (ISO 7270-1:2003), of which it constitutes a

minor revision. It also incorporates the Amendment ISO 7270-1:2003/Amd.1:2010.
The main changes compared to the previous edition are as follows:
— normative references have been updated in Clause 2.
A list of all parts in the ISO 7270 series can be found on the ISO website.

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
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INTERNATIONAL STANDARD ISO 7270-1:2020(E)
Rubber — Analysis by pyrolytic gas-chromatographic
methods —
Part 1:
Identification of polymers (single polymers and polymer
blends)

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 a method for the identification of polymers, or blends of polymers, in raw

rubbers and in vulcanized or unvulcanized compounds from pyrograms (pyrolysis-gas chromatographic

patterns) obtained under the same conditions. This allows qualitative identification of single rubbers

or blends, with exceptions discussed below. This document is not intended for quantitative analysis.

The method applies first and foremost to single polymers. When the pyrogram indicates a characteristic

hydrocarbon, the method is also applicable to blends. For details, see Clause 5. The method can be also

applicable to other types of polymer when verified by the analyst in each particular case.

NOTE The use of this document pre-supposes sufficient working knowledge of the principles and techniques

of gas chromatography to enable the analyst to carry out the operations described and to interpret the results

correctly.
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 1407:2011, Rubber — Determination of solvent extract
ISO 1629:2013, Rubber and latices — Nomenclature
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 https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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ISO 7270-1:2020(E)
4 Principle

4.1 Raw or vulcanized rubbers and/or their blends are pyrolysed and the pyrolysis products are

subjected to gas-chromatographic analysis under predefined conditions. The chromatograms produced

are referred to as pyrograms.

4.2 Pyrograms are interpreted by comparison with reference pyrograms produced from the same

rubbers and/or blends, prepared and analysed under the same conditions.
5 Single polymers and blends
5.1 General

The rubbers in the following listing are grouped in accordance with ISO 1629:2013.

5.2 Group M
a) Chlorinated polyethylene (CM) and chlorosulfonated polyethylene (CSM).

NOTE 1 The pyrogram will not differentiate between these chlorinated polyethylenes.

b) Ethylene-propylene copolymers (EPMs) and ethylene-propylene-diene terpolymers (EPDMs).

NOTE 2 The pyrogram can differentiate terpolymers from copolymers when the pyrogram indicates

characteristic “diene” monomer pyrolysis products.
c) Acrylic rubbers (ACMs).
5.3 Group O
Epichlorohydrin rubbers [homopolymer (CO), copolymer (ECO) and terpolymers].

NOTE The pyrogram will not differentiate between these various types of epichlorohydrin polymer.

5.4 Group Q
Polysiloxanes.
5.5 Group R
a) Polybutadiene (BR).

NOTE 1 The pyrogram will not differentiate between polymers containing different proportions of

isomers.
b) Polychloroprene (CR).

NOTE 2 The pyrogram will not differentiate between the various types of polychloroprene rubber, or

polychloroprene rubber from other types of chlorinated rubber.
c) Isobutene-isoprene copolymer (IIR).

NOTE 3 The pyrogram will not differentiate butyl rubber from its halogenated forms or from isobutene.

d) Polyisoprene (NR or IR).
NOTE 4 The pyrogram will not differentiate natural from synthetic polyisoprenes.
e) Acrylonitrile-butadiene copolymer (NBR).
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ISO 7270-1:2020(E)

NOTE 5 In some cases, NBR can be differentiated from hydrogenated acrylonitrile-butadiene copolymer

(HNBR). The pyrogram will not differentiate a single NBR from an NBR/BR blend or a blend of various

types of NBR.
f) Styrene-butadiene copolymer (SBR).

NOTE 6 In some cases, block polymers can be differentiated from random polymers. The pyrogram will

not differentiate a single SBR from an SBR/BR blend or a blend of various types of SBR.

5.6 Blends

With the exception of blends containing both styrene-butadiene copolymer and polybutadiene, the

method enables blends of the following polymers to be identified:
a) polyisoprene (NR or IR);
b) polybutadiene (BR);
c) isobutene-isoprene copolymers (IIRs);
d) styrene-butadiene copolymers (SBRs).
6 Reagents
All reagents shall be of analytical grade.
6.1 Solvents for extraction purposes
The following solvents are suitable (see 8.2):
6.1.1 Acetone.
6.1.2 Methanol.
6.1.3 Methyl ethyl ketone.
6.2 Carrier gas.
6.2.1 Nitrogen.
6.2.2 Helium.
6.3 Gas for flame-ionization detector: hydrogen plus purified compressed air.
7 Apparatus
7.1 Extraction apparatus
As specified in ISO 1407.
7.2 Pyrolysis/chromatography system
7.2.1 General

The apparatus utilized to obtain pyrograms consists of four parts: the pyrolysis device, the gas

chromatograph, the gas-chromatographic column and the data-handling equipment.
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ISO 7270-1:2020(E)
7.2.2 Pyrolysis device
The following types of electrically heated pyrolysis device are suitable:
7.2.2.1 Micro-furnace, with quartz tubes in which the test portion is pyrolysed.

7.2.2.2 Curie-point pyrolyser, with a holder (pyrolysis probe) containing ferromagnetic material

which surrounds the test portion and is heated to the Curie-point temperature to pyrolyse the test

portion.

7.2.2.3 Platinum-filament pyrolyser, with a holder (pyrolysis probe) containing a platinum filament

which surrounds the test portion and is heated to pyrolyse the test portion.
7.2.3 Gas chromatograph

A wide variety of chromatographs using either a flame-ionization detector (FID) or a thermal

conductivity detector (TCD) are suitable for use in this document.

Selective detectors such as electron capture detector (ECD), flame photometric detector (FPD),

flame thermionic detector (FTD), atomic emission detector (AED) can give useful information. For

identification of pyrolysis products, a mass spectrometer detector can be utilized.

7.2.4 Chromatographic columns

A variety of column lengths and diameters and stationary and liquid phases are suitable for use in this

document, the main requirement being good resolution of the volatile pyrolysis products.

NOTE 1 Capillary columns with good separation efficiency are suitable, but not essential.

NOTE 2 Capillary columns containing non-polar polydimethylsiloxanes and partially modified (diphenyl-,

cyanopropylphenyl- or other) semi-polar silicones are suitable.

NOTE 3 Usually, capillary columns require little evaluation, while it often is necessary to evaluate many

conditions for polar and non-polar packed columns.

The conditions chosen will depend on the column used. Typical operating conditions for the gas

chromatograph with both polar and non-polar columns can be found in Tables 1 to 5. Typical pyrograms

obtained can be found in Figures 1 to 44.
7.2.5 Data-handling equipment
A recorder, an integrator or a computer data-analysis system may be used.
8 Procedure

8.1 Accurate comparison of the pyrogram of an unknown polymer with the reference is only possible

under the same conditions.

8.2 Extraction of test samples is recommended to remove additives which may interfere with the

chromatographic separation. For oil-extended materials, extraction of the extender oil is essential

otherwise this oil may cause serious interference in the pyrogram. Carry out the extraction following the

general principles of either method A or method B in ISO 1407:2011. The chosen solvent shall not affect

the polymer and shall remove as much of the additives as possible. After extraction, dry the test sample,

as residual solvent may cause interference with the pyrolysis products (see 9.4).

8.3 Take a test portion of mass appropriate to the apparatus used. Generally, this will be between 0,1

mg to 5 mg. For good reproducibility, the size of the test portion should be as small as practicable.

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