ISO 4320:1977 pdf download – Non-ionic surface active agents – Determination of cloud point index – Volumetric method
1 SCOPE
This International Standard specifies a volumetric method for the determination of the cloud point index of non-ionic surface active agents.
2 FIELD OF APPLICATION
The method i s applicable to weakly alkoxylated non-ionic surface active agents (1 to 5 oxyethylene groups) the hydrophobic group of which is provided by an alcohol, an alkylphenol or a fatty acid (provided that the last has a melting point lower than 30 OC), subject to the product being soluble in propan-1-01 to the extent of 1 g in 10 ml at 30 “C. It is equally applicable to lipophilic bases derived from alcohols, alkylphenols and fatty acids.
3 REFERENCE
ISO 607, Surface active agents – Detergents -Methods of sample division.
4 DEFINITION
For the purposes of this International Standard, the following definition applies : cloud point index : The number of millilitres of distilled water necessary to render cloudy, at a specified tem- perature, a solution containing a given mass of surface active agent in a given volume of solvent.
5 PRINCIPLE
Addition, at 30 OC, of distilled water to a propanol solution of the surface active agent until the appearance of cloudiness.
7.1 Beaker (see the figure) of height 80 mm and diameter 50 mm, with double walls permitting temperature stability, and having a mass less than 200g, fitted with a poly- ethylene, polytetrafluoroethylene or an aluminium foil cover pierced with two holes allowing entry of the ther- mometer (7.2) and the burette (7.4).
Fit the beaker (7.1) onto the water bath (7.7) and control the temperature at 30,O f Oll O C . Start the water circulation and the stirrer (stir gently at first in order to avoid splashing the liquid on the walls of the beaker). Ensure that the test portion is completely dissolved (the solution should be clear) and add, drop by drop, the water (6.1) from the burette (7.4) until the liquid remains cloudy. Check that the temperature in the beaker i s maintained at 30,O f 0,5 OC during the complete operation. The results of the test depend upon the speed of introduc- tion of the water. Hence, the period during which it is introduced should be between 20 and 30 min, according to the quantity of water introduced. Immediately after the cloud point is reached, allow the solution to equilibrate for 5min so as to verify that the turbidity does not disappear.
10.1 Method of calculation
The cloud point index of the product is expressed as the volume, in millilitres, of water introduced to render cloudy I -ol mi of a 1 00 g/i solution of non-ionic surface active agent in propan-I -o1. Take as the result the mean of at least three determinations, expressed to the nearest 0,05 ml (1 drop of water).
10.2 Repeatability
The maximum difference between the results of two deter- minations carried out in rapid succession on the same sample, by the same analyst using the same apparatus, should not exceed 2 % of the mean volume found.
10.3 Reproducibility
The difference between results obtained on the same sample in two different laboratories should not exceed 5 % of the mean volume found.