ISO 19242-2015 pdf free.Rubber- Determination of total sulfur content by ion chromatography.
ISO 19242 specifies a method for the determination of the total sulfur content of raw rubber and unvulcanized or vulcanized rubber compounds by ion chromatography following the preparation of a sample solution using either a tubular furnace combustion or an oxygen combustion flask method.
The tubular furnace combustion method is applicable for rubbers with sulfur content less than 0,1 % as it is possible that the oxygen combustion flask method will not give sufficiently accurate results.
The oxygen combustion flask method is not applicable to rubbers containing a metal salt that forms an insoluble metal sulfate, such as barium sulfate.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 4661-2, Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests
3 Principle
3.1 Combustion
3.1.1 Tubular furnace combustion method
A test piece is burnt in an oxygen stream in a tubular furnace with an electrical heater. The sulfur in the test piece is oxidized to sulfur dioxide, which is absorbed into hydrogen peroxide solution and converted to sulfuric acid.
3.1.2 Oxygen combustion flask method
A test piece is burnt in the presence of oxygen in a flask. The sulfur in the test piece is oxidized to sulfur dioxide, which is absorbed into hydrogen peroxide solution and converted to sulfuric acid.
3.2 Determination
The sulfate from either the tubular furnace combustion or the oxygen combustion flask method is quantitatively analysed by ion chromatography, and the result is converted to the total sulfur content of the original rubber sample.
4 Reagents
Use only reagents of recognized analytical grade and only water as specified in 41.. The reagents for the tubular furnace combustion method are given in A.2. The reagents for the oxygen combustion flask method are given in BZ.
4.1 Water, of grade I or higher as specified in ISO 3696.
4.2 Sulfate stock standard solution, of a commercial standard solution with a certified sulfate concentration, e.g. 1 000 mg/dm3 of sulfate, traceable to national standards.
Observe the manufacturer’s expiry date or recommended shelf-life.
4.3 Sulfate calibration solutions, prepared by dilution of the sulfate stock standard solution (42) with water (4Jj.
Prepare at least four solutions of different concentration of sulfate covering the expected concentration from the sample. The solutions shall be prepared every analytical day.
4.4 Eluent solution, capable of eluting sulfate to a proper retention time in selected column.
Follow the column manufacturer’s instructions. Some examples of eluent are shown in Annex C.ISO 19242 pdf download.
Tags: Rubber
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