Carbon fibers from mixtures of AR and supercritically extracted mesophases

Abstract

Mixtures of two mesophase pitches derived from different raw material sources were investigated for producing high-performance carbon fibers. In particular, a high-melting, supercritically extracted (SCE) mesophase that was hard to spin but produced fibers with excellent properties was combined with AR mesophase, a relatively low-melting material. Mixtures of the SCE and AR mesophases ranging from 25 to 75% SCE were melt-spun into fiber form. The addition of 25% AR to the SCE mesophase dramatically improved its spinnability to the point that fiber yields were similar to those obtained for 100% AR. Surprisingly, fibers produced from the mesophase mixtures all stabilized more rapidly than those produced from either of the pure mesophases, with the fastest weight gain being obtained for the 25% SCE–75% AR mixture. DRIFTS was used to follow the stabilization reactions and confirmed these results. In general, final fiber properties of the mesophase mixtures were also superior to those of the pure mesophases. For example, significant improvements in both the thermal conductivity and Young’s modulus of AR mesophase were obtained with the addition of 25% SCE mesophase.