Graphite/Carbon Experts : Graphene

When I worked in Re-entry and Rocket Motor materials, the emphasis was mostly on various available advanced (and old) carbon/graphite materials.
"Experts" in these carbon materials would include many disciplines, including Mechanical Engineers who were only modest converts to atomic theory, needing to be weaned from Continuum Theories of matter.
Somehow, the Defense and NASA "Carbon Experts" had convinced themselves that carbons and graphites were so unique that they were a universe of their own particualr sciences.
"Experts" sometimes were those who compiled data or fabricated materials, but who never seriously thought of placing these "Highly Unique" carbon/graphite materials into the logical spectrum of other materials.
One of my favorite questions to ask some "Experts" went like the following.
I would show them a plot of the melting point versus the Elastic Modulus (Young's) and they could see that the high melting point materials had high elastic modulii. I wa careful to put Diamond on the chart, using the triple point as a substitute for the lack of atmospheric pressure melting poing.
Then I would show them the elastic moduli of Pyrolytic Graphite and of the Graphite Crystal. The "C" axis would show up with this incredibly low elastic modulus..... which is of course the macroscopic manifestation of the weak vad der Waals bonding in that direction.
Then I would ask them "How is it that this weakly bonded material has such a high melting point?"
Generally, the result was a rambling mumble or silence.
Sometimes I would also throw in a graph of thermal expansion coefficient versus melting point..... and the low thermal expansion materials would have high melting point.
Then there would sometimes be the inverse correlation of melting point and elastic modulus..... (stiff materials would generally be low thermal expansion, such as Tungsten versus high expansion low melting materials such as Aluminum),
I hid from these discussions the critical data trend of melting point of various organic materials versus linearity/planarity and "molecular weight".
It was interesting that the "Experts" in the carbon/graphite materials had insulated themselves from materials science and chemistry.
Fullerenes, Buckytubes and Graphene did not, evidently, originate from the community of carbon and graphite "Experts".
Could be wrong.
Jim
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Jim,
I can give you some thoughts on graphene if you can accept it as non-expert knowledge.
I have layman observations with it now and have been a lot of fun to work with. Damn it looks fine when polished!
Seeing as how the stuff has some mysterious (possibly amazing) potential, why not fling some more ideas around?
I'd love to start a dialog about this fullerene stuff. I believe current thinkers have missed a huge opportunity..
sincerely, Scott Yannitell
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aSkeptic wrote:

I am a "Scientist" rather than "Discoverer" or "Dreamer".
I love taking a mess of knowledge and finding of other people and making logical sense or science out of it.
I do not "Cruise on the edges of science".... as some do.
Many of these "Cruisers of the edge of science" love to get involved with something quite new, and almost everything you do is therefore new and publishable.
The "Cruisers of the Edge..." COTE for short, are not capable of sustained interest in something.... to where they will spend years making SCIENCE out of observation.
Right now, "Graphene" is in the hands of COTE, and I have little interest.
The COTE will make inflated statements about the POSSIBILITIES..... oh, those possibilities,,,, ever so tantalizing..... and OH SO IMPORTANT, if they come true.
But, I avoid that excitement. I prefer the struggle to make an orderly knowledge structure.... not to find NEW EXCITING IMPORTANT things.
So, I pass on the offer to participate in new exciting things.
By the way, nobody even attempted to asnwer the key question that was posed.......
How can Graphite be one of the most refractory substances we know, if it has weak covalent bonding in one of the three dimensions?
Look at all of the COTE about the mention of graphene.... and the overlook of a significant problem of understanding that has been around for well over 100 years.... mostly ignored.
Refractory materials are empirically known to be a consequence of strong atomic bonds.....
YEt there is Graphite that is only van der Waals bonded in one dimension, and it is an outstanding refractory material (in the abselnce of oxygen, of course).
Nobody bit or stepped up to the plate with the answer, did they?
However, answering questions like that is a key part of science.
Maybe there isn't that much science in Materials Science as they used to claim?
Jim
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But Jim, the same problems are even worse with carbon nanotubes, which depend on Van der Waals forces in 2-dimensions for their intermolecular bonding. Perhaps if the same solutions (functionalization, larger molecular size and interface area) could be tried on the graphene sheets, they'd yield similar results if not better ones.
Perhaps graphene molecules can provide benefits individually, without having to be bonded to lots of other things. Perhaps they can do things unrelated to mechanical strength, like the high-speed ciruits.
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sanman wrote:

And you simply demonstrated what I said about COTE -- those who love to cruise on the edge.....
Instead of science, one gets hope and fantastic promises of potential.
Incidently, the answer to my question of extreme high melting point and "weak" van der Waals bonding has yet been unanswered, and it indeed does have an immediate answer.
SO where the devil is any science going on in this discussion...?
Nowehere.
Just stupid claims of wonder in the next round of "Leading Edge" materials.
COTE -- too often, not enough discipline to answer hard logical questins.
Jim
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Hiya, nowhere in that post did I make any fantastic promises of potential. I said that some of the approaches that are being tried for nanotubes may address the concerns you mentioned for graphene.
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sanman wrote:

I have ABSOLUTELY NO concerns for graphene.
I am NOT interested.
I can't understand how you would imagine I have any concern for graphene.
YOU SAID

which looks like empty promises for the stuff. Well? What was the purpose of this stuff above that you cleverly cut out when replying to me?
Empty potential wonderful promises ! !
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