Carbon Fiber Processing and Structure/Property Relations

Abstract

Two varieties of carbon fibers dominate high performance composite applications: PAN-based and pitch-based. PAN-based carbon fibers tend to exhibit higher strengths (both tensile and compressive) than do pitch-based carbon fibers. Consequently, they are preferred in applications where strength is critical. Pitch-based carbon fibers develop higher lattice-dependent properties (modulus and thermal conductivity) and, thus, are used when stiffness or heat transfer limits composite performance. Since the effect of structure on properties is identical for all carbon fibers, the characteristic properties of PAN-based and pitch-based carbon fibers reflect fundamental differences in their structures. The internal structures of these two varieties of carbon fibers are, in turn, a direct result of the processes used to produce them.