Carbon Black Content
APPARATUS AND GLASSWARES
- Electrical combustion furnace – maintained at 1000°± 25°C.
- Muffle furnace – 550°± 25°C, 1000 ± 25°C
- Silica or porcelain crucible
- Combustion tube.
- Porcelain boat (combustion type)
- Nitrogen gas cylinder.
- Weighing balance.
- Determination of fillers, in test specimen
- Heat the furnace with the combustion boat to temperature 1000± 25°C.
- Place the boat in furnace maintained at temperature 1000°C for 15 minutes.
- Cool in Desiccator and weigh accurately to 0.001 g as M1.
- In the boat, weigh about 1 g of homogenized sample and take the mass of sample with boat as M2.
- Draw out the combustion tube a little bit from the hot zone and pass nitrogen for 1 minute to drive the air.
- Put the boat with sample into the combustion tube slightly away from hot zone.
- Connect the nitrogen gas flow and push the tube such that boat is in the hot zone of furnace.
At first dense, black-brown smoke will come out of combustion tube and finally turns into white smoke.
- When white smoke becomes thinner, draw out the combustion tube from the furnace.
- Continue the nitrogen flow for 2-3 minutes more.
- Cut off the nitrogen supply into the tube.
- Take out the boat carefully avoiding spilling and keep it in a Desiccator till it is cooled.
- Weigh the boat with the ignited sample as M3.
Calculate total fillers, percent by mass accordingly as follows
Total fillers, percent by mass = M3 – M1 x 100 / M2 – M1
- M3= mass in g of the boat with the sample after ignition,
- Ml = mass in g of empty boat, and
- M2 = mass in g of the boat with sample.
Determination of Ash Content
- Heat the crucible at 550°± 25°C in muffle furnace for half an hour.
- Remove the crucible and cool in Desiccator.
- Weigh quickly and note the dry weight of crucible as B.
- Weigh 1.0 g of test specimen into this weighed crucible. Note mass of sample as C.
- Place the crucible with sample in the furnace and close the door completely.
- After 1 hour, open the furnace door 3 to 5 cm and continue heating for 30 minutes.
- As soon as all carbonaceous materials are burned off, remove the crucible from the furnace.
- Cool in a Desiccator and weigh the mass of ash and crucible as A.
Calculate ash, percent by mass as follows:-
Ash, percent by mass = A – B x 100 / C
A = mass in gram of ash and crucible.
B = mass in gram of crucible.
C = mass in gram of test specimen
Calculate the carbon black content as follows:
Carbon black, percent by mass = Total fillers – Total ash.