S.H. Hong et al. Carbon 37(1999)917-930 L01 SPUF I ISKU loaf sk SPUN I3 b°8a Fig. 1. HR-SEM photographs of transverse cross-section of the mesophase pitch-based(a, b, c)as-spun,(d, e, f) xtraction with pyridine, and carbon fibers heat-treated at(g, h, i)1000C and (, k, I)2400C: spinning temperature 310C of as-spun fiber random orientation of microdo- mains of rectangular shapes with ca. 500-1000 nm size mains of ca. 50 size(Fig. Ic). The whole cross- and pores scattered among the domains(Fig. Id). The high sectional surface fiber appears to consist of such magnification photograph(Fig. If of the extracted as-spu microdomains, showing that the skin and core are homoge- fiber exhibited insoluble microdomains of ca 50-100 nm hous at the magnification of size to show almost the same size compared to that of the The photograph of low magnification in the extracted as-spun fiber without extraction, which formed the do- s-spun fiber showed randomly distributed insoluble do- mains of variable shapes by connection of microdomainsS.-H. Hong et al. / Carbon 37 (1999) 917 –930 919 Fig. 1. HR–SEM photographs of transverse cross-section of the mesophase pitch-based (a, b, c) as-spun, (d, e, f) as-spun fibers after extraction with pyridine, and carbon fibers heat-treated at (g, h, i) 10008C and (j, k, l) 24008C: spinning temperature 3108C. of as-spun fiber exhibited random orientation of microdo- mains of rectangular shapes with ca. 500–1000 nm size mains of ca. 50–100 nm size (Fig. 1c). The whole cross- and pores scattered among the domains (Fig. 1d). The high sectional surface of the fiber appears to consist of such magnification photograph (Fig. 1f) of the extracted as-spun microdomains, showing that the skin and core are homoge- fiber exhibited insoluble microdomains of ca. 50–100 nm neous at the magnification of 50 000 (Fig. 1b). size to show almost the same size compared to that of the The photograph of low magnification in the extracted as-spun fiber without extraction, which formed the do￾as-spun fiber showed randomly distributed insoluble do- mains of variable shapes by connection of microdomains