Thermal properties of graphite

The physical properties reviewed in the previous section are essentially unaffected by the size and orientation of the crystallites in the aggregate (with the exception of density). As a result, they can be considered valid for all forms of graphite. This is no longer true for some of the properties listed in this and the following sections, and these properties may vary considerably depending on crystallite size and orientation and other factors related to the processing conditions. 

The thermal properties are summarized in Table 3.4. Whenever possible, a range of property values is given. More detailed values are given in subsequent chapters. 

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Vol 10 "The Thermal Properties of Graphite ft "Lamellar Reactions in Gtaphitizable Carbons and in Vol 11 "Highly Oriented Pyrolytic Graphite 7) G. Cohn, Edit, Explsft-Pyrots 7(1), 1974 (Lists Vols 8—11 of the above book and suggests (hat the paper on electronic properties in Vol 8 may be of interest in connection with carbon bridge detonators)... 

Laser Raman spectroscopy complements ssNMR in characterizing the different types of carbonaceous structures formed in the charred materials. Indeed, in the Raman spectra of graphite, there are many features that can be identified and that can provide information about the properties of the materials, such as their electronic structure as well as information about imperfections or defects. Since mechanical, elastic, and thermal properties of graphite are influenced by its structure, Raman spectra could provide interesting information regarding the carbonization process.1617... 

The Thermal Properties of Graphite, B. T. Kelly and R. Taylor Lamellar Reactions in Graphitizable Carbons, M. C. Robert, M. Oberlin, and J. Mering... 

Profatilova, I. A. Choi, N-S. Roh, S. W Kim, S. S., Electrochemical and thermal properties of graphite electrodes with imidazolium- and piperidinium-based ionic liquids, J. Power Sources., 2009, 192, 636-643. 

Koutides DA, Review of thermal properties of graphite composite materials, NASA Technical Memorandum 100049, 1987. 

Yasmin, A. Daniel, I.M. Mechanical and thermal properties of graphite plated/epoxy... 

Fig. 2. With-giain thermal properties of artificial graphite (1).

Radiolytic oxidation alters most of the important properties of graphite, including strength, elastic modulus, work of fracture, thermal conductivity, permeability, and diffusivity but does not affect the thermal expansion coefficient or Poisson s ratio. The effects of radiolytic oxidation on the properties of a wide range of graphites have been studied in the U.K. [7,73,74] where it was found that, to a first approximation, they can be described by similar relationships ... 

Ohki, Y., Taomoto, A., Tsuchiya, S., Kawashima, T. and Nishiki, N., Thermal properties of newly developed flexible graphite sheet. In Extended Abstracts and Programme of Science and Technology of Carbon Eurocarbon 98), Vol. II, Strasbourg, France, July 6-7, 1998, pp. 679 680. 

Experimental results are presented that show that high doses of electron radiation combined with thermal cycling can significantly change the mechanical and physical properties of graphite fiber-reinforced polymer-matrix composites. Polymeric materials examined have included 121 °C and 177°C cure epoxies, polyimide, amorphous thermoplastic, and semicrystalline thermoplastics. Composite panels fabricated and tested included four-ply unidirectional, four-ply [0,90, 90,0] and eight-ply quasi-isotropic [0/ 45/90]s. Test specimens with fiber orientations of [10] and [45] were cut from the unidirectional panels to determine shear properties. Mechanical and physical property tests were conducted at cold (-157°C), room (24°C) and elevated (121°C) temperatures. 

Fig. 6.6 (a) A comparison of mechanical and thermal properties of PMMA hybrids with SWNT, expanded graphite (EGr) and functionalized graphene sheets (FGS). (b) Percentage synergy in hardness and modulus of the hybrids with binary nanocarbon fillers (from [44]). 

DeVincent, S.M. and Michal, G.M. (1993b). Improvement of thermal and mechanical properties of graphite/copper composite through interfacial modification. J. Mater. Eng. Performance (JMEPEG) 2, 323-332. 

The hyperbranched polymers are carbon-rich macromolecules and show excellent thermal stabilities. The thermal properties of the hb-PAs are described below as an example. Their thermal stabilities were evaluated by TGA. Figure 3 shows TGA thermograms of some hb-PAs and Table 4 lists their thermal analysis data. The hb-FAs were thermally very stable for instance, hb-P66 lost merely 5% of its weight at a temperature as high as 595 °C. All the polymers, except for hb-F(44-Vl) and hb-F(59-Vl), carbonized in > 50% yields on pyrolysis at 800 °C, with hb-P(45-V) graphitized in a yield as high as 86% (Table 4, no. 3). The thermal stabilities of the hb-PAs are similar to that of Unear pol-yarylenes such as PPP but different from those of Unear polyacetylenes such as PH and PPA. The dramatic difference in the thermal stability is mainly due to the structural difference PPP is composed of thermally stable aromatic rings (Td 550 °C) [108-112], whereas PPA and PH are comprised of labile polyene chains, which start to decompose at temperatures as low as 220 and 150 °C, respectively [113]. The excellent thermal stabilities of the hb-FAs... 

Some research reactors are equipped with a so-called thermal column of about 1 m X 1 m X 1 m, consisting of blocks of graphite and installed near the reactor core. Due to the moderator properties of graphite, only thermal neutrons are present in such a column. 

Deposition, Structure, and Properties of Pyrolytic Carbon, J. C. Bokros The Thermal Conductivity of Graphite, B. T. Kelly... 

The most stable graphites are the near-isotropic materials ". The effects of irradiation on the properties of graphite are governed by neutron energy, neutron fluence, temperature, temperature gradients, and structure and type of graphite used. The effects of irradiation are dimensional changes, reduction in thermal conductivity, and enhancement of creep rates. 

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