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Kein Timothy Capuno

How to measure the apparent porosity and bulk density of the...

David Fenderson  Follow

1. determine the true density of your sample by helium pycnometry;
2. paint the graphite sample with a varnish of known density (in order to avoid that water enters into the structure) and determine the bulk density of your samples using the Archimedes's method;
3. determine the total porosity according to the equation: P = 1- bulk density/true density
Regards,
Fernando Costa Oliveira


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Caleb Brunson  Follow

Dear Awani,

Mercury Intrusion Porosimetry (MIP) is a widely used technique for mesuring the porosity, total pore volume, total pore surface area, pore size distribution etc. covering a wide range of materials including catalysts, resrvoir rocks, ceramics, graphites and many other porous materials.


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Benjamin van As  Follow

Porosity can also be measured with micro-CT. However, this is no cheap method of measurement.


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Asbin  Follow

You may also try image analysis. For this you need to impregnate your sample with (metallography) resin and polish it. using image analysis method, you can obtain the apparent volume of your sample (including the pores) and subsequently the apparent density. The difference between the apparent density and real density is the apparent porosity in the sample (porosity=1-AD/RD).


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David Poling  Follow

For answers to another graphite density related question posed at this forum ─ «How do we find the bulk density and particle density of exfoliated graphite flaks in Lab?», see: https://www.researchgate.net/post/How_do_we_find_the_bulk_density_and_particle_density_of_exfoliated_graphite_flaks_in_Lab

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Charles Michaud  Follow

Archimedes principle

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Chee-Eng, Lim  Follow

A think that the notion of "apparent porosity" does not exist. while, "closed porosity" and "total porosity" or "open porosity" is used instead.
if you talk about the open or accessible porosity , you can determine it using the vacuum saturation method.
For the bulk density determination, the method proposed by our collegue Fernando Oliveira is the most common used method " paint the graphite sample with a varnish of known density (in order to avoid that water enters into the structure) and determine the bulk density of your samples using the Archimedes's method"


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David A Miller  Follow

Dear Awani, please try mercury porosimetry...


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Alfred Dumasi  Follow


Dear Awani,

This way it may be quite good for your measurement.

Must prepare various EG samples for crosscheck. To prepare samples, preparation must be done by the sudden heating of graphite intercalated compound (GIC) with varying particle size of different meshes number in an electrical furnace at different temperatures range. The pore structure of expanded graphite (EG) including pore volume, pore size distribution and surface area is investigated by mercury porosimetry, nitrogen adsorption and SEM. The EGs can be characterized by FTIR to evaluate the presence of functional groups. The bulk density of EG can be determined by measuring the mass and apparent volume of an EG sample. The volume can be measured where EG poured into a volumetric flask without compaction. Moreover, the particle size of GIC and exfoliation temperature can be studied to know the strong effects on the pore size of EG, exfoliation temperature decreases, the sorption capacity decreases; and EG samples prepared from the GICs with smaller particle size might have lower sorption capacity. The mercury intrusion porosimetry and nitrogen adsorption isotherms can reveal the information of that nano meter pores in EG samples. Silicone oil can be used for the sorption experiments.

Ashish

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Anthony Picco  Follow

Maybe try sedimentation. You should create the gradient of density, put it to the centrifuge and see, where your graphite stops.


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Deevan Dilpat Rai  Follow

The Archimedes' method is the most practical method when an irregular shape, porous body is in concern. Try and contact a ferrites manufacturer if there is one reachable around, as they use mercury for this measurement, and they may come cheapest of all... Image analysis is also a solution if the distribution of the pores is uniform, and a random cut through the body of the sample can be taken as representative.


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