ISO 6840:1982 カチオン性界面活性剤（塩酸塩および臭化水素酸塩）—臨界ミセル化濃度の決定—対イオン活性の測定による方法 | 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 6840 was developed by Technical Committee ISO/TC 91, Surface active agents, and was circulated to the member bodies in November 1981.

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

No member body expressed disapproval of the document.

0 Introduction

Curves showing the variations in the physical properties of aqueous solutions of surface active agents are specific to these products; over a certain concentration range, which is usually very narrow, these curves show a singularity. This phenomenon has been attributed to the formation of oriented aggregates of molecules, and the concentration at which this change occurs has been termed the"critical micellization concentration" (c.m.c.).

For a given hydrophobic chain length, 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, nature and quantity of 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 measurements of potential (it is very useful to know the organic or mineral nature of these impurities and, if possible, their concentrations).

1 Scope and field of application

This International Standard specifies a method for the determination of the critical micellization concentration of cationic surface active agents (hydrochlorides and hydrobromides) in solution in distilled water or other aqueous systems, by measurement of the counter ion activity using a membrane electrode.

The method is applicable to purified or unpurified cationic surface active agents (hydrochlorides and/or hydrobromides), which are soluble in water and which have a Krafft temperature below 60 °C.

2 References

3 Definitions