High thermal-conductivity mesophase pitch-based graphite fiber with circular cross-section through a spinneret with a Y-shaped spinning hole

As one kind of special carbon fiber with very high thermal conductivity, mesophase pitch-based graphite fiber (MPGF) is very important in many applications. MPGFs with high thermal conductivity usually have a ribbon or splitting structure, while carbon fibers used in resin-based composite or carbon/carbon composite commonly have circular or approximately circular cross-section structure. Herein, a kind of MPGF with circular cross-section and high thermal conductivity was prepared. The precursor fiber (PF) was prepared by using melt spinning with a Y-shaped spinneret. The cross-section of the PF is triangular, and gradually transforms into round during the preparation process. It was noteworthy that the graphite microcrystals of the final MPGF aligned in a very unique arrangement along the radial direction. The obtained MPGFs have high orientation and graphitization degree, and its thermal conductivity is as high as 1070 W/(m·K).