Recent advances in studies of carbon fibre structure

Abstract

Carbon fibre structure is usually characterized by means of X-ray diffraction measurement and electron microscope observation. The meaning of the most important parameters is discussed in terms of the structures revealed by high resolution transmission electron microscopy. Recently, dark-field electron microscopy and electron diffraction of selected areas has been used to reveal and characterize skin-core and sheath—core heterogeneity in type I (2500 °C) polyacrylonitrile (PAN)-based carbon fibres. Lattice-fringe electron microscopy has given some insight into the nature of the surface layers in type I, type II (1500 °C) and type A (1000 °C) fibres. The skin regions of type I fibres are seen to contain misorientated crystallites interlinked in a complex manner; these are flaws that will limit the intrinsic tensile strength of the material.

Cellulose‐Derived Carbon Fibers with Improved Carbon Yield and Mechanical Properties

“…This could be attributed to an imperfect crystalline, turbostratic carbon structure. [56,57] With increasing temperature, however, an increase in crystallite size manifested itself through more pronounced and narrower reflections (lower full width at half maximum (FWHM)). With the growth of the crystallites, the (002) reflection moved from 2θ = 18.5° at 400 °C to 2θ = 25.0° at 2200 °C.…”

New Perspectives on the Structure of Graphitic Carbons

“…68 High-resolution TEM shows that the fibers have an imperfect structure, containing many elongated voids. Several models have been put forward for the structure of PAN-derived carbon fibers, all based on the assumption that the basic structural units are graphite sheets or ribbons.…”

Synthesis and Characterization of Wooden Magnetic Activated Carbon Fibers with Hierarchical Pore Structures

“…In order to examine the differences between the microcrystalline structures of the WMACFs at various Fe 3 O 4 contents, the apparent value of the planar size ( L a (110) ), the bulk thickness ( L c (002) ) of the graphite sheet layer, the average crystallite size ( D ), and the layer spacing d 002 were calculated using the Scherrer and Bragg formulas [22,23]. The formulas were as follows: L c (002) , D = 0.89λ/βcosθ L a (110) = 1.84λ/βcosθ d 002 = λ/2sinθ where λ is the wavelength of the X-ray (0.154 nm); θ is the Bragg angle of (002), (100), and (311) peaks (°); and β is the half-height width of (002), (100), and (311) peaks (rad).…”