EN ISO 2554:1998

SLOVENSKI STANDARD
01-maj-2000
3ROLPHUQLPDWHULDOL1HQDVLþHQHSROLHVWUVNHVPROH'RORþDQMHKLGURNVLOQHJD
ãWHYLOD,62
Plastics - Unsaturated polyester resins - Determination of hydroxyl value (ISO
2554:1997)
Kunststoffe - Ungesättigte Polyesterharze - Bestimmung der Hydroxylzahl (ISO
2554:1997)
Plastiques - Résines de polyesters non saturés - Détermination de l'indice d'hydroxyde
(ISO 2554:1997)
Ta slovenski standard je istoveten z: EN ISO 2554:1998
ICS:
83.080.10 Duromeri Thermosetting materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
IS0
STANDARD
Second edition
1997-03-01
Plastics - Unsaturated polyester resins -
Determination of hydroxyl value
Plastiques - Msines
polyesters non sat&s - D&ermina tion de
I’indice d’hydroxyle
Reference number
IS0 2554: 1997(E)
IS0 2554: 1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0
member bodies). The work of preparing International Standards is normally carried out through IS0 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. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an international Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard IS0 2554 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12,
Thermosetting materials.
This second edition cancels and replaces the first edition (IS0 2554:1974), of which it constitutes a minor (editorial)
revision.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
IS0 2554: 1997(E)
INTERNATIONAL STANDARD o IS0
Plastics - Unsaturated polyester resins - Determination of
hydroxyl value
1 Scope
This International Standard specifies a method for determining the hydroxyl value of unsaturated polyester resins.
In fact, this method determines the difference between the hydroxyl value and the acid value; it is therefore
necessary to determine the total acid value separately, in order to calculate the hydroxyl value.
NOTE 1 The hydroxyl value of saturated polyester resins (for example, polyester resin used for the manufacture of
polyurethanes and polymeric plasticizers) and of certain types of alkyd resins may also be determined by this method.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 2114:1996, Plastics - Unsaturated polyester resins - Determination of partial acid value and total acid value.
- Specification and test methods.
IS0 3696: 1987, Water for analytical laboratory use
3 Definitions
For the purposes of this International Standard, the following definitions apply:
3.1 hydroxyl value: The number of milligrams of potassium hydroxide necessary to neutralize the acetic acid
which will combine, by acetylation, with 1 g of an unsaturated polyester resin.
3.2 acid value: The number of milligrams of potassium hydroxide required to neutralize 1 g of a test sample under
the test conditions.
3.3 total acid value: The acid value corresponding to the neutralization of all carboxyl-terminated groups and free
acids and free anhydrides of a polyester.
4 Principle
The hydroxyl groups in the resin are acetylated by reacting an ethyl acetate solution of the resin with acetic
anhydride in the presence of toluene-4-sulfonic acid catalyst. The excess acetic anhydride is hydrolysed by a
pyridine/water mixture and the resultant acetic acid is titrated with methanolic potassium hydroxide solution.
0 IS0
IS0 2554: 1997(E)
hyd rid e groups which exist in the resin are also neutralized by the
In this titration, the free acid and free an
potassi urn hydroxide.
The hydroxyl value is finally calculated by taking into account the total acid value determined separately by
IS0 2114.
5 Reagents
During the analysis, use only reagents of recognized analytical grade and water of
...