Working on polystyrene & graphite composite, interesting effect(s)

[James Cox]

Dear Folks:

I have been experimenting with composite conductor materials for a while, but have had little success with getting conductivity below 200 ohms/cm.

Polystyrene gel is easy to make and offers recycling opportunities, so I have been using this as a starter binder.

Found that if graphite powder is in a suspension with acetone and then 'reacted' with polystyrene gel in acetone, the gel will absorb the graphite from suspension till an approximate proportion of .725gr graphite:1.0gr weighted styrofoam raw. Very little graphite remains in the acetone suspension.

From this attempted to see if the polystyrene/graphite composite was stable. I obtained a high speed blender with distilled water and wiped the composite gel at high speed as I poured it in. The graphite did not separate out into the water, but the composite broke up into small flakes. These flakes have low conductivity, so still stuck. After drying the flakes, reexposed them to acetone, they took a while to re-gel but did return to near original mass/gel.

Questions:

a) what is the underlying 'chemistry' affecting the absorbtion of graphite?
b) any suggestions to improve conductivity?
c) would exfoliation of the graphite help?
d) would other solvent system help?
e) open to suggestions.

Graphite & polystyrene gel composites are mentioned in the literature, but no mention of this proportion.

A similar reaction takes place with a graphite/manganese dioxide acetone suspension, but the polystyrene seems to cross link becoming stringy and stiff, but has my best low conductivity. This has toxicity issues.

James

 

[chemisttree]

The aromatic groups of the polystyrene have an affinity for the planar extended 'aromatic' sheets of graphite. That could explain the affinity of the graphite to the PS. Conductivity in graphite requires the charge carrier to hop from one extended sheet of graphite to another. PS is coating the surface, however, and will block that from happening by keeping the sheets too far away from each other. A binder level over 50% with an insulating polymer (PS in this case) is not likely to conduct electricity extremely well. You would be better served to use a soluble conducting polymer such as sulfonated polyphenylene-vinylidine to preform your part. Thermal processing will remove the sulfur trioxide, resulting in a composite of graphite/polyphenylene-viylidine which, once formed, will resist further processing (it won't redissolve).

What is 'exfoliation of the graphite'?

 

[Blueshift5]

,

Thank you for sharing your interesting findings on the polystyrene and graphite composite. I find it fascinating that the gel is able to absorb such a high proportion of graphite from the suspension. It seems like the composite is stable to some extent, as it did not separate out into the water during blending. However, the low conductivity of the resulting flakes is still a challenge.

To answer your questions:

a) The absorption of graphite by the polystyrene gel is likely due to the polar nature of the acetone solvent. The polar groups in the polystyrene gel can interact with the polar groups on the surface of the graphite particles, allowing for absorption into the gel matrix.

b) To improve conductivity, you may want to consider increasing the proportion of graphite in the composite, or try using a different solvent system that may allow for better dispersion and absorption of the graphite.

c) Exfoliation of the graphite may help to increase conductivity by increasing the surface area available for interaction with the polystyrene gel. This can be achieved through mechanical or chemical methods.

d) Other solvent systems may also help to improve conductivity. You could try using solvents with different polarities or using a combination of solvents to achieve better dispersion and absorption of the graphite.

e) I would suggest exploring different solvents and possibly trying different proportions of graphite to see if you can improve conductivity. Additionally, you could experiment with different methods of incorporating the graphite into the polystyrene gel, such as pre-treating the graphite or using different mixing techniques.

It is interesting to note that similar reactions occur with other materials, such as the graphite/manganese dioxide acetone suspension. This suggests that there may be potential for using other materials in combination with the polystyrene gel to achieve different properties and conductivity levels.

Thank you for sharing your work and I look forward to seeing how your research progresses. Keep up the interesting work!