ISO INTERNATIONAL STANDARD 2554 Second edition 1997-03-01 Plastics --- Unsaturated polyester resins Determination of hydroxyl value Plastiques -- Résines de polyesters non saturés - Détermination de l'indice d'hydroxyle ISO Reference number ISO 2554:1997(E) py IHS under lic Not for Resale ISO 2554:1997(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 sO 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 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 ISO 2554 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12 Thermosetting materials This second edition cancels and replaces the first edition (IsO 2554:1974), of which it constitutes a minor (editorial) revision. ISO1997 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by anymeans, electronic ormechanical, including photocopying and microfilm, without permission in writing from the publisher International Organization for Standardization Case postale 56.CH-1211Geneve 20.Switzerland Internet [email protected] X.400 C=ch; a=400net; p=iso; 0=isocs; S=central Printed in Switzerland Not for Resale INTERNATIONAL STANDARD ISO ISO 2554:1997(E) 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 revision, and parties to agreements based on this International Standard are encouraged to investigate the registers of currently valid International Standards. IsO 2114:1996, Plastics - Unsaturated polyester resins - Determination of partial acid value and total acid value. IsO 3696:1987, Water for analytical laboratory use - Specification and test methods. 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 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. Copyright International Organization for Standardizatior Not for Resale