Carbon fibres from mesophase pitch

Abstract

Union Carbide Corporation has recently developed a process for preparing high-modulus carbon fibres from mesophase pitch. These high-modulus carbon fibres can be prepared from low-cost carbonaceous pitches which have been converted to a liquid crystal state. The liquid crystal or mesophase state results when a proper size distribution of planar aromatic molecules is produced by dehydrogenative condensation reactions. Mesophase pitches can be melt-spun into fibres possessing a high degree of axial preferred orientation which can be preserved and enhanced through carbonizing and graphitizing. Mesophase pitch-derived carbon and graphite fibres can have several transverse structures and are capable of achieving various combinations of high strength and high modulus. Their electronic properties are extremely sensitive to structure and further confirm the graphitizability of carbon fibres derived from mesophase pitch. A number of strength-limiting defects have been identified and their incidence reduced. The number of applications of carbon fibres continues to increase. The unique structure and properties of mesophase pitch-based carbon fibres make them particularly suitable for those applications requiring high stiffness, high electrical conductivity, high thermal conductivity, and low coefficient of thermal expansion.