BS ISO 9924-2:2016 pdf free

BS ISO 9924-2:2016 pdf free.Rubber and rubber products一Determination of the composition of vulcanizates and uncured compounds by thermogravimetry
A weighed test portion is heated, following a pre-set programme, from 40 °C to 600 °C in a stream of nitrogen until all the organic material is pyrolysed. If nitrile-butadiene copolymers are present, a small amount of the polymer will be pyrolysed to form a carbonaceous residue that has to be determined in order to obtain the correct total organic content.
For this purpose, the oven temperature is decreased to 400 °C in a stream of nitrogen and maintained at 400 °C for 5 min. The gas stream is then changed from nitrogen to air or oxygen and the oven temperature raised slowly to 800 °C. During this heating in an oxidizing atmosphere, two distinct losses in mass occur due to combustion. The first is due to the combustion of the carbonaceous residue, and the amount is determined and added to the previously determined loss in nitrogen at 600 °C to obtain the correct value of the total organic content. The second is due to the normal combustion of the carbon black.
NOTE  The total rubber content is calculated by subtracting the value of the solvent extract, determined in accordance with ISO 1407, from the total organic content, provided that all non-rubber ingredients can be extracted.
Calcium carbonate will decompose to calcium oxide when heated to 800 °C. Carbon black is thermally stable up to this temperature in a nitrogen atmosphere. In air or oxygen, however, carbon black will be oxidized to carbon dioxide at 800 °C.
Provided that nitrogen having a low enough concentration of oxygen is used, that purging is carried out for a time greater than the purge time determined in 6.1, that there are no leaks in the apparatus, and that the oven design and gas flow rate ensure that all carbon dioxide is swept out from the sample chamber, there should be no problem in distinguishing between, and measuring separately, black and whiting (calcium carbonate). To check the operation of the thermogravimetric analyser, carry out the following procedure.BS ISO 9924-2 pdf free.