ISO 4311:1979 陰イオン性および非イオン性界面活性剤—臨界ミセル化濃度の決定—プレート、あぶみ骨、またはリングで表面張力を測定する方法 | ページ 2

FOREWORD

ISO (the International Organization for Standardization) is a worldwide federation of national standards institutes (ISO member bodies). The work of developing International Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up 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.

Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council.

International Standard ISO 4311 was developed by Technical Committee ISO/TC91, Surface active agents, and was circulated to the member bodies in October 1975.

It has been approved by the member bodies of the following countries:

The member body of the following country expressed disapproval of the document on technical grounds:

United Kingdom

0 INTRODUCTION

Curves showing the variation in the physical properties of aqueous solutions of surface active agents are specifical to individual products; in a certain region of concentration, usually very narrow, these curves show a sharp change of slope. This phenomenon has been attributed to the formation of orientated aggregates of molecules, and the concentration at which this change occurs has been termed the"critical micellization concentration" (c.m.c.)¹⁾.

For a given length of hydrophobic chain, the critical micellization concentration is usually higher in the case of ionic surface active agents than in the case of non-ionic surface active agents. Apart from the structure of the surface active agent, the temperature, and the presence, the nature and the quantity of the metallic salts, organic compounds cause the critical micellization concentration to vary, and hence the operational conditions likely to influence the result must be clearly stated, i.e. the purity of the product and, as far as possible, its impurities, which may greatly alter the value of surface tension measurements (it is very useful to know the organic or mineral nature of these impurities and, if possible, their concentrations). On account of these interactions a definite value cannot be obtained for the critical micellization concentration, but generally its range can be defined by the curve showing the variations in the surface tension, which in practice is deemed satisfactory.

1 SCOPE

This International Standard specifies a method for the determination of the critical micellization concentration of anionic and non-ionic surface active agents in solution in distilled water or other aqueous systems, by measurement of the surface tension with a plate, stirrup or ring.

3 REFERENCES

4 DEFINITIONS