ISO 7781:2017 specifies three methods for the determination of the soap and organic-acid content of raw styrene-butadiene rubber (SBR).
- Method A is the titration method using indicator reagent.
- Method B is the titration method using an automatic potentiometric titrator.
- Method C is the back titration method using an automatic potentiometric titrator.
Since the soaps and organic acids present in the rubber are not single chemical compounds, the method gives only an approximate value for the soap and organic-acid content.