Accelerated titration method

Determination of the level of total sulfur in a rubber can give information on the type of cure system used, for example, elemental sulfur plus accelerator or sulfur donor system, etc. The ISO 6528-1 1992 method — Rubber — Determination of total sulfur content — Part 1 Oxygen combustion flask method is often employed. The principle of the method is oxidation by ignition in an atmosphere of oxygen in the presence of hydrogen peroxide, conversion of sulfur to sulfuric acid and determination of the sulfate by titration with barium perchlorate. The method is... 

Oxidation processes involving the subsequent titration of an excess of ferrous sulphate,2 oxalic acid (in the presence of silver sulphate as catalyst), titanous chloride,4 or of the quantity of iodine liberated from potassium iodide,5 are also available but are less satisfactory. In the last-named method a large excess of potassium iodide is necessary to obtain complete reaction in a short time. The reaction may be accelerated by the addition of potassium chloride6 or ammonium chloride with 20 per cent, by weight of the latter salt present a large excess of the iodide is not necessary and the liberated iodine may be titrated after fifteen minutes.7... 

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