NBN EN 1890:2006

This document specifies methods for the determination of the cloud point of solutions of non-ionic surface active agents obtained by the reaction of ethylene oxide with a hydrophobic base molecule.
This document primarily applies to surfactants obtained by reaction of ethylene oxide with hydrophobic base molecules, such as fatty alcohols, fatty acids, long-chain alkylphenols, fatty amines, fatty acid esters of sugar derivatives among other ethoxylated non-ionic surfactants, which are by far the most commonly used.
NOTE Other non-ionic surfactants containing other structural units, such as propylene oxide-ethylene oxide block copolymers, have distinctive behaviours that make the determination of the cloud point more difficult. This leads sometimes to a gradual turbidity over a temperature range of several degrees or even to the occurrence of two cloud points at significantly different temperatures.