Description of terms:
- CARBON FIBERS TYPE IM (INTERMEDIATE MODULUS) are related to CARBON FIBERS TYPE HT because of the comparable values of tensile strength, but are characterized by greater stiffness. Note: The tensile modulus (Young’s modulus) varies ca. 275-350 Gpa, but the disposition of the boundaries is somewhat arbitrary. The relatively high tensile strength required is achievable by a significant reduction of the single filament diameter down to about 5 um. Such small filament diameters are typical of CARBON FIBERS TYPE IM.
- CARBON FIBERS TYPE LM (LOW MODULUS) are CARBON FIBERS with isotropic structure, tensile modulus values as low as 100 Gpa and low strength values.
- CARBON FIBERS TYPE UHM (ULTRA HIGH MODULUS) designates a class of CARBON FIBERS having very high values of Young’s modulus, greater than 600 Gpa. Note: Such high values of Young’s modulus can be achieved most readily in MESOPHASE PITCH BASED CARBON FIBERS (MPP based carbon fibers).
- CARBONACEOUS MESOPHASE is a liquid crystalline state of PITCH which shows the optical birefringence of disc-like nematic crystals. It can be formed as an intermediate phase during thermolysis of an isotropic molten PITCH, or by precipitation from PITCH fractions prepared by selective extraction. With continuous heat treatment, the CARBONACEOUS MESOPHASE coalesces to state of BULK MESOPHASE before solidification to GREEN COKE, with further loss of hydrogen or other low molecular weight compounds.
- CARBONIZATION is a process by which solid residues with increasing content of elemental carbon are formed from organic material, usually by pyrolysis in an inert atmosphere. As with all pyrolytic reactions, CARBONIZATION is a complex process in which many reactions take place concurrently, such as dehydrogenation, condensation, hydrogen transfer and isomerization. The final pyrolysis temperature applied controls the degree of CARBONIZATION and the residual content of foreign elements.
- CHAR is a solid decomposition product of a natural or synthetic organic material.
- CHARCOAL is a traditional term for a CHAR obtained from wood, peat, coal or other related natural organic materials.
- COAL TAR PITCH is a residue produced by distillation or heat treatment of coal tar. It is solid at room temperature, consists of a complex mixture of numerous, predominantly aromatic hydrocarbons and heterocyclics, and exhibits a broad softening range, instead of a defined melting temperature.
- COKE is a solid, high in elemental carbon content and structurally in the NON-GRAPHITIC state. It is produced by pyrolysis of organic material which has passed, at least in part, through a liquid or liquid-crystalline state during the CARBONIZATION process. COKE can contain mineral matter.
- COLLOIDAL CARBON is a PARTICULATE CARBON with particle sizes below ca. 1000 nm in at least one direction.
- DIAMOND is an allotropic form of the element carbon, with cubic structure which is thermodynamically stable at pressures above 6 GPa at room temperature and metastable at atmospheric pressure. At low pressures and temperatures above 1900K in an inert atmosphere, DIAMOND converts rapidly to GRAPHITE. The chemical bonding between the carbon atoms is covalent, with sp3 hybridization.
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