ISO INTERNATIONAL STANDARD 1065 Second edition 1991-09-01 ANSi Irternat Doc Sed Non-ionic surface-active agents obtained from ethylene oxide and mixed non-ionic surface-active agents --- Determination of cloud point et mixtes --- Determination de la temperature de trouble (point de trouble) Reference number ISO 1065:1991(E) Not for Resale IS0 1065:1991(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, govern- mentail and non-governmental, in liaison with IsO, also take part in the work. iso collaborates closely with the International Electrotechnical Commission (lEC) on alf matters of electrotechnical standardization. Draft International Standards adopted by the technicai committees are circulated to the member bodies for voting. Publication as an Inter- nationai Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard tsO 1065 was prepared by Technical Committee ISO/TC 91, Surface active agents. secondeditioncancelisand replaces the first edition This (Iso 1065:1975), to which two new methods (D and E) have been added in order to extend the scope to cover mixed non-ionic surface-active agents. C ISO 1991. or by any means, electronic or mechanical, including photocopying and microfim, without permission in writing from the pubiisher. Internationat Organization for Standardization Case Postale 56: CH-1211 Geneve 20 : Switzerland Printed in Switzerland yrghneationalrganizatiStandadizatio ed without license from IHS Not for Resale ISO 1065:1991(E) Introduction Aqueous solutions of non-ionic surface-active agents derived from ethylene oxide become heterogeneous when their temperature is raised, because of the formation of two liquid phases. The temperature above which this phenomenon occurs is referred to as the cloud point. This phenomenon occurs at a temperature which increases as the number of molecules of ethylene oxide combined in the product in- creases. The system becomes homogeneous when the temperature falls. The temperature at which the system becomes homogeneous is called the “temperature of clarification" as defined in isO 862:1984. Surface active agents -- Vocabulary (definition No.10). point" The knowledge of the cioud point is of great importance in all appli- cations, as the surface-active properties vary very rapidly around this temperature. The determination of the cloud point of a non-ionic product is a rapid and precise method of control. in manufacture, it is the quickest method of assessing the quantity of ethylene oxide bonded to a given base molecule. However, it must be remembered that the curve relating cloud point and the extent of ethoxylation tends towards an asymptote; as a consequence, this method of checking is less precise for products with a long ethoxyl chain. The cloud temperature is a lower critical temperature of separation; above this critical temperature, the solution separates into two phases, leads to the clouding of the solution. This property is not specific to ethoxylated derivatives and it is possible to determine cloud tempera- tures for other types of derivative. Methods A, B and C specified in this International Standard deal pri- marily with the determination of the cloud point of non-ionic surface- ethylene oxide by active agents derived from condensation with lipophilic base molecules such as fatty alcohols, fatty amines, fatty ac- ids, alkylphenols and esters of fatty acids. Other non-ionic surface-active agents, e.g. ethylene oxide/propylene oxide block copolymers, are known to have properties which make it difficult to determine their cloud points. Such properties