NBN ISO 1304:2021

This International Standard specifies methods for the determination of iodine adsorption number of
carbon blacks for use in the rubber industry. Two titration methods are described:
— method A: titration using a burette and starch as indicator;
— method B: potentiometric titration with an automatic titrator.
The iodine adsorption number is related to the surface area of a carbon black and is generally in
agreement with the nitrogen surface area. However, it is significantly depressed in the presence of a
high content of volatile or solvent-extractable materials; the iodine adsorption number therefore does
not always provide a measure of the specific surface area of a carbon black. Ageing of carbon black can
also influence the iodine number.
In case of dispute, the preferred method is method B (potentiometric titration).