This document specifies three methods for the determination of ash from raw rubbers, compounded rubbers and vulcanizates. The methods are applicable to raw, compounded or vulcanized rubbers of the M, N, O, R and U families described in ISO 1629, except that:
— Method A is not used for the determination of ash from compounded or vulcanized rubbers containing chlorine, bromine or iodine;
— Method B is used for compounded or vulcanized rubbers containing chlorine, bromine or iodine. It shall not be used for uncompounded rubbers;
— Method C is intended to be used for the determination of ash from raw, compounded or vulcanized rubber not containing chlorine, bromine or iodine by wrapping the test portion in ashless filter paper;
— Lithium and fluorine compounds might react with silica crucibles to form volatile compounds, giving low ash results. Platinum crucibles shall therefore be used for ashing fluorine-containing and lithium-polymerized rubbers.
This document does not cover the interpretation of the ash results as to the inorganic chemical content of a compound or vulcanizate. This is the responsibility of the analyst, who has to be aware of the behaviour of rubber additives at elevated temperatures.