This International Standard specifies a method for the determination of the soap and organic-acid content of raw styrene-butadiene rubber (SBR). The method depends on the extraction of the organic acids and soaps form the rubber by means of a solvent. In practice, therefore, it is convenient to determine both organic-acid and soap contents on separate portions of the same solvent extract. Since the soaps and organic acids present in the rubber are not single chemical compounds, the method gives only an approximative value for the soap and organic-acid content.
The method is applicable to all types of styrene-butadiene rubber, but slight modifications are required for oil-extended rubbers.