ISO 1125 pdf download.Rubber compounding ingredients — Carbon black — Determination of ash
1 Scope
This International Standard specifies a method for determining the ash of all types of carbon black for use in the rubber industry.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 1 1 24:1 988, Rubber compounding ingredients — Carbon black shipment sampling procedures . ISO/TR 9272:1 986, Rubber and rubber products — Determination of precision for test method standards .
3 Principle
An accurately weighed portion of dried sample is ignited in a crucible until all the carbonaceous material is oxidized. The crucible is cooled in a desiccator, weighed, and the percentage of ash calculated.
4 Apparatus
4.1 Muffle furnace, capable of maintaining a temperature of 550 °C ± 25 °C (or other required temperature). NOTE The use of a vented furnace would decrease the time of heating to constant mass (see 6.3). 4.2 Porcelain crucible, tall form, diameter 35 mm, height 30 mm, with lid. The use of the lid on the crucible is optional. If it is not used, this shall be mentioned in the test report. 4.3 Analytical balance, accurate to 0,1 mg.4.4 Desiccator.4.5 Oven, preferably of the gravity-convection type, capable of temperature regulation to within ± 1 °C at 1 25 °C and temperature uniformity to within ± 5 °C.
5 Sampling
Carry out sampling in accordance with ISO 1 1 24.
6 Procedure
6.1 Heat the crucible (4.2), with its lid (if used), in the muffle furnace (4.1 ) at a temperature of 550 °C ± 25 °C for 1 h. Place the crucible (and lid) in the desiccator (4.4). Cool to ambient temperature and reweigh to the nearest 0,1 mg. NOTE If, after cleaning, drying and reweighing at the end of the determination (see 6.4), the crucible is stored in a dessicator, step 6.1 is needed only for new crucibles. 6.2 Dry a little more than 2 g of furnace carbon black or a little more than 5 g of thermal or channel carbon black in the oven (4.5) at a temperature of 1 25 °C for 1 h. Allow to cool to room temperature. 6.3 Weigh, to the nearest 0,1 mg, about 2 g of dried furnace carbon black or 5 g of dried thermal or channel black into the crucible tared in 6.1 , place in the furnace at a temperature of 550 °C ± 25 °C and heat uncovered until constant mass is obtained. Cover with the lid (if used), remove to the desiccator, and allow to cool to ambient temperature. Weigh to the nearest 0,1 mg. To avoid repeated handling of the crucible, an adequate ashing time shall be established at each test site. IMPORTANT — Take the following precautions: a) keep the door of the furnace open about 0,5 cm to admit air to support the combustion of organic material; b) after the test portion has cooled in the desiccator, admit air slowly to avoid loss of ash from the crucible due to air currents. By mutual agreement between the interested parties, it is permissible to use another ashing temperature such as 750 °C ± 25 °C or 825 °C ± 25 °C (subclauses 4.1 , 6.1 and 6.3 would have to be adapted accordingly). However, this temperature leads to lower ash contents than the ones obtained at 550 °C, and shall not be used for reference purposes. 6.4 Clean the crucible (and lid), dry in the oven (4.5) at 1 25 °C and reweigh to the nearest 0,1 mg.