ISO 5260:2023

Epoxidized natural rubber — Determination of epoxidation and ring opening level by NMR spectrometry

This document specifies a quantitative method, using proton (1H) nuclear magnetic resonance (NMR) spectrometry, for the determination of epoxidation and ring opening level of raw epoxidized natural rubber (ENR). This method applies to ENR of all grades available commercially.

Caoutchouc naturel époxydé — Détermination de l'époxydation et du niveau d'ouverture des anneaux par spectrométrie RMN

General Information

• Status: Published
• Publication Date: 08-Jun-2023
• ICS: 83.060 - Rubber
• Technical Committee: ISO/TC 45/SC 3 - Raw materials (including latex) for use in the rubber industry
• Drafting Committee: ISO/TC 45/SC 3/WG 4 - Natural rubber
• Current Stage: 6060 - International Standard published
• Start Date: 09-Jun-2023
• Due Date: 30-Jul-2023
• Completion Date: 09-Jun-2023

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 5260
First edition
2023-06
Epoxidized natural rubber —
Determination of epoxidation and ring
opening level by NMR spectrometry
Caoutchouc naturel époxydé — Détermination de l'époxydation et du
niveau d'ouverture des anneaux par spectrométrie RMN
Reference number
ISO 5260:2023(E)
© ISO 2023

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ISO 5260:2023(E)
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© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO 5260:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 2
7 Procedure .2
7.1 Sample preparation . 2
7.2 NMR measurement . 3
8 Calculation . 3
9 Precision . 3
10 Test report . 3
1
Annex A (informative) H NMR spectra of ENR 25 and ENR 50 . 5
Annex B (informative) Precision . 6
Bibliography . 9
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ISO 5260:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry.
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.
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ISO 5260:2023(E)
Introduction
Epoxidized natural rubber (ENR) is one of the modified rubbers derived from natural rubber (NR).
The modification process is done by introducing oxygen atom to the unsaturated molecule of NR. This
chemical reaction produces an oxirane or epoxide compound that consists of a three-membered ether
in a cyclic form. A few grades of ENR are currently available depending on the extent of modification
such as ENR 25 (25 mole% epoxide) and ENR 50 (50 mole% epoxide).
ENR is used in many applications which include tyres, bearings and adhesives. Epoxidation and ring
opening level are very important parameters to check ENR quality. Various techniques are available
for quantification of the epoxidation level, such as elemental analysis (carbon, hydrogen and oxygen),
1 13
infrared spectroscopy (IR), proton ( H) and carbon ( C) nuclear magnetic resonance spectroscopy
(NMR), as well as the chemical titrimetric technique.
1
This document specifies a quantitative method, using proton ( H) nuclear magnetic resonance
spectrometry, for the determination of epoxidation and ring opening level of raw ENR. This test method
is an important document to support ISO 24483, as these parameters are included as specifications for
ENR. This work will benefit the market to specify a measurement method for the epoxidation and ring-
opening level of ENR.
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INTERNATIONAL STANDARD ISO 5260:2023(E)
Epoxidized natural rubber — Determination of
epoxidation and ring opening level by NMR spectrometry
1 Scope
1
This document specifies a quantitative method, using proton ( H) nuclear magnetic resonance (NMR)
spectrometry, for the determination of epoxidation and ring opening level of raw epoxidized natural
rubber (ENR). This method applies to ENR of all grades available commercially.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
epoxidized natural rubber
ENR
natural rubber which has been chemically treated and modified through the addition of oxygen atom
onto the double bond structure of the cis-1,4-polyisoprene to form three-membered ether (C-O-C) in a
cyclic form by a process known as epoxidation reaction
[SOURCE: ISO 24483:2023, 3.1]
3.2
epoxidation level
level and/or degree of the epoxy groups (C-O-C) in the NR structure
[SOURCE: ISO 24483:2023, 3.4]
3.3
ring opening level
level and/or degree of ring opening due to the formation of secondary by product from uncontrolled
condition of epoxidation reaction in the
...