HIGH THERMAL-CONDUCTIVITY RIBBON FIBERS FROM NAPHTHALENE-BASED MESOPHASE

Their extremely high thermal conductivity, combined with their relativ ely low density, make mesophase pitch-based carbon fibers attractive f or many applications where heat transfer is critical. Although many th ermal management applications could create large markets for mesophase fibers, the current high cost of these fibers makes their use unecono mical. The objective of the present research is to produce low-cost, m esophase pitch-based carbon fibers with high mechanical and thermal pr operties. In the current study, circular and ribbon fibers were produc ed from a naphthalene-based mesophase. After stabilization and carboni zation, their mechanical and electrical properties were compared to fi bers produced at similar conditions, but using a heat-soaked mesophase precursor. The ribbon fibers produced from the naphthalene-based meso phase exhibited higher moduli and electrical resistivities than round fibers formed from the same precursor. Also, the mechanical and electr ical properties of the naphthalene-based ribbon fibers were superior t o ribbon fibers previously produced using a heat-soaked mesophase and heat treated at equivalent conditions. At carbonization temperatures o f only 2250-degrees-C, the ribbon fibers produced from naphthalene-bas ed mesophase developed electrical resistivities as low as 2.68 muohm . m, a factor of three lower than those previously produced from the he at-soaked mesophase. Thus, ribbon fibers formed from naphthalene-based mesophase should exhibit higher thermal conductivities than either ro und fibers formed from the same precursor or ribbon fibers formed from a heat-soaked precursor. An additional benefit is that fibers formed from naphthalene-based mesophase develop excellent properties at relat ively low carbonization temperatures.