'''Graphitizing''' and '''non-graphitizing''' carbons (alternatively graphitizable and non-graphitizable carbon) are the two categories of [[carbon]] which are produced by [[pyrolysis]] of organic materials. They were first identified by [[Rosalind Franklin]] first identified them in a 1951 paper in ''[[Proceedings of the Royal Society|]]''Proceedings of the Royal Society'']].<ref>{{cite journal|author= R.E. Franklin |title= Crystallite growth in graphitizing and non-graphitizing carbons |journal= Proceedings of the Royal Society A|volume=209|pages=196-218196–218 |year=1951 }}|issue= 1097 {{DOI| authorlink = Rosalind Franklin| doi = 10.1098/rspa.1951.0197|bibcode= 1951RSPSA.209..196F |s2cid= 4126286 }}</ref>. In this paper, she defined graphitizing carbons as those whichthat couldcan be transformedtransform into crystalline graphite by heatingbeing heated to a temperature of {{cvt|3000°|C|K F}}, while non-graphitizing carbons coulddo not be transformedtransform into graphite at any temperature. Among[[Precursor the(chemistry)|Precursors]] precursorsthat which producedproduce graphitizing carbon wereinclude [[polyvinyl chloride]] (PVC) and petroleum coke, while. [[polyvinylidenePolyvinylidene chloride]] (PVDC) and [[sucrose]] producedproduce non-graphitizing carbon. The physicalPhysical properties of the two classes of carbons are quite different. Graphitizing carbons are soft and non-porous, while non-graphitizing carbons are hard, low density materials. Non-graphitizing carbons are otherwise known as “chars”''chars'', “hard''hard carbons”carbons'' or, more colloquially, [[charcoal]]. [[Glassy carbon]] is also an example of a non-graphitizing carbon material.
The precursors for graphitizing carbons pass through a fluid stage during pyrolysis ([[carbonization]]). This fluidity facilitates the molecular mobility of the aromatic molecules, resulting in intermolecular dehydrogenative polymerization reactions to create aromatic, lamellar (disc-like) molecules. These “associate”"associate" to create a new liquid crystal phase, the so-called mesophase. A fluid phase is the dominant requirement for the production of graphitizable carbons.<ref name= Mesophase >H. Marsh and M.A. Diez (1994) " Mesophase of Graphitizable Carbons" In: Shibaev V.P., Lam L. (eds) Liquid Crystalline and Mesomorphic Polymers. Springer, New York, NY {{DOIdoi| 10.1007/978-1-4613-8333-8_7 }}</ref>
Non-graphitizing carbons generally do not pass through a fluid stage during carbonization. ASince numberthe time of modelsRosalind haveFranklin, beenresearchers have put forward fora theirnumber structureof sincemodels thefor timetheir of Franklinstructure. Oberlin and colleagues have emphasised the role of basic structural units (BSU), made of planar aromatic structures consisting of less than 10-2010–20 rings, with 4four layers or fewer. Cross-linking between the BSUs in non-graphitizing carbons prevents [[graphitization]].<ref>{{cite journal|author= A. Oberlin |title= Carbonization and graphitization |journal= Carbon|volume=22|pages=521-541521–541 |year=1984}}|issue= 6 {{DOI|doi = 10.1016/0008-6223(84)90086-1}}</ref>. More recently, modelssome have been put forward whichmodels that incorporate pentagons and other non-six-membered carbon rings.<ref>{{cite journal|author= P.J.F. Harris |title= Fullerene-like models for microporous carbon |journal= Journal of Materials Science |volume=48|pages=565–577|year=2013}}{{DOI|issue= 2 |doi= 10.1007/s10853-012-6788-1|bibcode= 2013JMatS..48..565H |s2cid= 14903411 |url= http://centaur.reading.ac.uk/28956/1/Revised%20JMS%2031%20July%20For%20Centaur.pdf }}</ref>
==See also==
*[[Acheson process]]
*[[Carbonization]]
*[[Graphite]]
== References ==
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