ISO 21048:2014

INTERNATIONAL ISO
STANDARD 21048
Second edition
2014-02-15
Plastics — Epoxy resins —
Determination of 1,2-glycol content
Plastiques — Résines époxydes — Détermination de la teneur en
1,2-glycol
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – 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 Reagents . 2
6 Apparatus . 4
7 Procedure. 4
8 Expression of results . 5
9 Precision . 5
10 Test report . 6
Foreword
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The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting
materials.
This second edition cancels and replaces the first edition (ISO 21048:2004), which has been technically
revised.
iv © ISO 2014 – All rights reserved

Introduction
In producing epoxy resin based on epichlorohydrin, impurities containing 1,2-glycol may be formed.
Owing to the hydrophilic characteristics of 1,2-glycol, it is necessary to control the level of these
impurities, since they could affect final properties such as electrical insulation. Additionally, these
impurities could affect the speed of the curing reaction when using curing agents such as amines and
acid anhydrides. Therefore, it is important to determine the 1,2-glycol content in epoxy resins for both
resin manufacture and customer use.
INTERNATIONAL STANDARD ISO 21048:2014(E)
Plastics — Epoxy resins — Determination of 1,2-glycol
content
SAFETY STATEMENT — Persons using this document should be familiar with normal laboratory
practice, if applicable. This document does not purport to address all of the safety concerns, 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 regulatory requirements.
1 Scope
This International Standard specifies a method for the determination of the 1,2-glycol content in epoxy
resins.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
1,2-glycol
the 1,2-glycol group [-CH(OH)CH OH] in epoxy resins, the content of which is expressed in moles per
kilogram of the epoxy resin
Note 1 to entry: This moiety is chemically equivalent to two OH groups.
Note 2 to entry: Other possible nomenclatures are vicinal-OH group, 1,2-dihydroxyl group, α-glycol group.
4 Principle
1,2-glycol is determined on the basis of the following reactions.
1,2-glycol is oxidized to aldehyde compounds by an excess of orthoperiodic acid (reaction 1), then
potassium iodide is added to the reaction mixture in the presence of sulfuric acid (reaction 2). The
generated iodine is then titrated by standardized sodium thiosulfate solution (reaction 3). The 1,2-glycol
...