The structure and properties of ribbon-shaped carbon fibers with high orientation

Abstract

Using a naphthalene-derived mesophase pitch as a starting material, highly oriented ribbon-shaped carbon fibers with a smooth and flat surface were prepared by melt-spinning, oxidative stabilization, carbonization and graphitization. The preferred orientation, morphology and microstructure, as well as physical properties, of the ribbon-shaped carbon fibers were characterized. The results show that, the ribbon-shaped fibers possessed uniform shrinkage upon heat treatment, thereby avoiding shrinkage cracking commonly observed in round-shaped fibers. As heat treatment progressed, the ribbon-shaped graphite fibers displayed larger crystallite sizes and higher orientation of * Corresponding author. Tel.: Fax: +86 27 86556906 E-mail address: xkli8524@sina.com (X. Li) 2 graphene layers along the main surface of the ribbon-shaped fiber in comparison with corresponding round-shaped fibers. The stability of the ribbon-shaped graphite fibers towards thermal oxidation was significantly higher than that of K-1100 graphite fibers.The longitudinal thermal conductivity of the ribbon fibers increased, and electrical resistivity decreased, with increasing the heat treatment temperatures. The longitudinal electrical resistivity and the calculated thermal conductivity of the ribbon-shaped fibers graphitized at 3000°C are about 1.1 μΩ m and above 1100 W/m K at room temperature, respectively. The tensile strength and Young's modulus of these fibers approach 2.53 and 842 GPa, respectively.

Mesophase pitch-based graphite fiber-reinforced acrylonitrile butadiene styrene resin composites with high thermal conductivity

“…The benchmark graphite fibers (K-1100) with very high axial thermal conductivity also similarly form an open wedge crack structure at the transverse section [16,21]. Although such cracks can be reduced…”

“…Intensity/ (a.u.) and meridional scans for MPGFs show a significant difference due to their highly anisotropic structure [16]. Intensity/ (a.u.)…”

“…Round-shaped MPGFs were prepared by melt-spinning a commercial naphthalene-derived synthetic mesophase pitch (produced by Mitsubishi Gas Chemical Corporation) followed by complete oxidative stabilization, carbonization and final graphitization at 2500, 2700 and 2900 °C [16]. These MPGFs had various diameters in the range of 10~55 µm (and each batch typically has a slight, ± 5 µm, differential in diameter owing to multi-hole spinning).…”

A comprehensive study on the oxidative stabilization of mesophase pitch-based tape-shaped thick fibers with oxygen

“…The resulting unidirectional carbon tape/carbon composites can achieve ultrahigh thermal conductivity (800~900 W/ m K) in the longitudinal direction of the fibers [26,27]. In addition, tape-shaped carbon fiber does not split during subsequent heat treatment, in contrast to common round-shaped fiber due to the latter's radial transverse texture [24,25]. Therefore, tape-shaped carbon fibers have significant advantages in potential applications.…”

“…However, tape-shaped carbon fibers can be made with a rectangular cross-section (with width up to 1~4 millimeters and thickness of 10~20 m) that is equivalent to the total cross-sectional area of 100~200 conventional round-shaped carbon fibers. The tape-shaped fiber has a highly ordered structure, with the basal plane layers oriented predominantly parallel or perpendicular to the tape surface, which exhibits higher graphitizability and better thermophysical properties [23][24][25] than round-shaped fibers. Furthermore, the tape geometry does not limit the volume fraction of fibers that can be incorporated in a laminate, allowing a higher packing density, compared with the 74% v/v packing limit for round-shaped carbon fibers, in the preparation of carbon/carbon composites.…”