ISO 26603:2008 pdf download.Plastics — Aromatic isocyanates for use in the production of polyurethanes — Determination of total chlorine.
Introduction of ISO 26603:
socyanates are typically produced by phosgenation of an aromatic amine using chlorine-substituted benzenes (e.g. o-dichlorobenzene) as reaction solvents. SO 15028 is used to determine the hydrolyzabl chlorine content of the isocyanates. The test methods in this International Standard are used to determine the total chlorine content of aromatic isocyanates. The difference between the total chlorine content and the hydrolyzable chlorine content is a measure of the reaction solvents left in the product, and therefore is a useful tool for assessing product quality.
ISO 26603:2008 is used to determine the total chlorine content of aromatic isocyanates used in the preparation of polyurethanes. The difference between the total chlorine content and the hydrolyzable chlorine content (see ISO 15028) is a measure of the process solvents left in the product. Both test methods are applicable to a variety of organic compounds, including aliphatic isocyanates, but the amount of sample used might need to be adjusted. These test methods can be used for research or for quality control.
4 Principle
In each test method, the organic matter in the sample is destroyed by combustion with oxygen, thi converting the organically combined chlorine to ionic chloride. The chloride is determined potentiometrically by
titration with silver nitrate (AgNO3)solution.
4.1 Test Method A
Combustion of the sample is done in a pressurized oxygen bomb.
4.2 Test Method B
Combustion is done at atmospheric pressure in a Schoniger oxygen flask
NOTE For information on the Schoniger flask, refer to Reference.
5 Interferences
Thiocyanate, cyanide, sulphide, bromide, iodide or other substances capable of reacting with silver ion, as well as substances capable of reducing silver ion in acid solution, will interfere with the determination.
6 Sampling
Since organic isocyanates react with atmospheric moisture, take special precautions in sampling. Usual sampling methods, even when conducted rapidly, can expose the isocyanate to moisture and cause contamination of the sample with insoluble ureas; therefore, blanket the sample with a dry inert gas (e.g nitrogen, argon or dried air ) at all times.ISO 26603:2008 pdf download.
ISO 26603:2008 Plastics — Aromatic isocyanates for use in the production of polyurethanes — Determination of total chlorine
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