S.-H. Hong et al. Carbon 38(2000)805-815 B ,m;b°8 Fig. 2. HR-SEM photographs of the skin area observed from(a)parallel (0)and(b)30% to the fiber axis in the mesophase pitch-based carbon fiber heat-treated at 2400 C: spinning temperature 310.C. The longer axes of the microdomains are aligned parallel to the fiber surface as shown in A. The spurs are also aligned parallel to the longer axis of the microdomains within them as shown in B did not show any differences. Neither fibrils nor pleats 4. Discussion were observed in the longitudinal surface, although wavy ripples were evident. Microdomains of ca. 50 nm in 4.1. Mesoscopic texture at the skin area of mesophase diameter were observed in the transverse cross-sectional surface, although no particular transverse texture was The present study was aimed at clarifying the mesos- Fig 6 shows HR-SEM photographs of the skin area copic texture of mesophase pitch-based graphitized carbon ne three as-spun fibers after extraction with pyridine and fibers especially at the skin area in its transverse section successively heat-treated at 1000C. These fibers had where the texture exhibits three-dimensional shape and definitely more straight domains than those of the carbon- dimension of the microunits in the carbon fiber. The ized fibers obtained without pyridine extraction regardless graphitized fiber consists of rectangular plate -like micro of the macroscopic transverse textures. The spurs and mains of dimensions 20 nm thick, 30-50 nm wide, and graphene edges along the longer axis of microdomain 100-150 nm long. Several such microdomains form faced directly to the fiber surface after the removal of the domains with linear, bent and loop shapes in the transverse soluble component. The microdomains and spurs run section. The domains are macroscopically arranged typi parallel to the fiber surface disappeared in the carbonized cally in radial, random, and onion-like texture as often fiber after the extraction, although the orientation of reported [15,16] microdomains was basically the same as for carbonized The edges of the microdomains in the transverse section fibers without extraction. A much sharper angle wa are of special interest in the present study. The longer observed at the junction of two zig- zag microdomains at dges of the rectangular plate-like microdomains are the skin area in the extracted as-spun fiber spun at 340C oriented perpendicular to the surface in the radial and an in the corresponding graphitized fiber. Hence, no spur random textures, indicating apparently that the prismatic running around the top or any encounter edge of the edges may meet perpendicular to the fiber surface, al microdomains was observed any longer as shown at A in though domains in the former and latter textures are Fig 6a-c principally radial and very random, as illustrated in Fig. 7.808 S.-H. Hong et al. / Carbon 38 (2000) 805 –815 Fig. 2. HR-SEM photographs of the skin area observed from (a) parallel (08) and (b) 308 to the fiber axis in the mesophase pitch-based carbon fiber heat-treated at 24008C: spinning temperature 3108C. The longer axes of the microdomains are aligned parallel to the fiber surface as shown in A. The spurs are also aligned parallel to the longer axis of the microdomains within them as shown in B. did not show any differences. Neither fibrils nor pleats 4. Discussion were observed in the longitudinal surface, although wavy ripples were evident. Microdomains of ca. 50 nm in 4.1. Mesoscopic texture at the skin area of mesophase diameter were observed in the transverse cross-sectional pitch-based graphitized fiber surface, although no particular transverse texture was recognized. The present study was aimed at clarifying the mesos￾Fig. 6 shows HR-SEM photographs of the skin area in copic texture of mesophase pitch-based graphitized carbon the three as-spun fibers after extraction with pyridine and fibers especially at the skin area in its transverse section successively heat-treated at 10008C. These fibers had where the texture exhibits three-dimensional shape and definitely more straight domains than those of the carbon- dimension of the microunits in the carbon fiber. The ized fibers obtained without pyridine extraction regardless graphitized fiber consists of rectangular plate-like microdo￾of the macroscopic transverse textures. The spurs and mains of dimensions 20 nm thick, 30–50 nm wide, and graphene edges along the longer axis of microdomain 100–150 nm long. Several such microdomains form faced directly to the fiber surface after the removal of the domains with linear, bent and loop shapes in the transverse soluble component. The microdomains and spurs running section. The domains are macroscopically arranged typi￾parallel to the fiber surface disappeared in the carbonized cally in radial, random, and onion-like texture as often fiber after the extraction, although the orientation of reported [15,16]. microdomains was basically the same as for carbonized The edges of the microdomains in the transverse section fibers without extraction. A much sharper angle was are of special interest in the present study. The longer observed at the junction of two zig-zag microdomains at edges of the rectangular plate-like microdomains are the skin area in the extracted as-spun fiber spun at 3408C oriented perpendicular to the surface in the radial and than in the corresponding graphitized fiber. Hence, no spur random textures, indicating apparently that the prismatic running around the top or any encounter edge of the edges may meet perpendicular to the fiber surface, al￾microdomains was observed any longer as shown at A in though domains in the former and latter textures are Fig. 6a–c. principally radial and very random, as illustrated in Fig. 7