Graphitizing and non-graphitizing carbons: Difference between revisions

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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]] in a 1951 paper forin [[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=196-218 |year=1951 }} {{DOI| 10.1098/rspa.1951.0197}}</ref>. In this paper she defined graphitizing carbons as those which could be transformed into crystalline graphite by heating to a temperature of 3000°C, while non-graphitizing carbons could not be transformed into graphite at any temperature. Among the precursors which produced graphitizing carbon were [[polyvinyl chloride]] (PVC) and petroleum coke, while [[polyvinylidene chloride]] (PVDC) and [[sucrose]] produced non-graphitizing carbon. The physical 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”, “hard carbons” or, more colloquially, [[charcoal]]. [[Glassy carbon]] is also an example of non-graphitizing carbon.

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” 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 {{DOI| 10.1007/978-1-4613-8333-8_7 }}</ref>