Abstract: A carbon fiber powder is produced by graphitizing a polymeric fiber having an aromatic ring on its main chain by heating and then pulverizing or cutting it. The polymeric fiber is selected from the group consisting of polybenzazole fiber, aromatic polyamide fiber, aromatic polyimide fiber, polyphenylene sulfide fiber, and wholly aromatic polyester fiber. The carbon fiber is preferably graphitized by heating the polymeric fiber at least 2500 degree C. under vacuum or in an inert gas. Thus, the carbon fiber powder that has excellent thermal conductivity and filling capability, a method of making the carbon fiber powder, and a thermally conductive composition including the carbon fiber powder are provided.

Abstract: Graphitized carbon powder are produced by carbonizing and expanding a pitch by heating to form carbonaceous foam and by graphitizing before pulverizing or graphitizing after pulverizing the carbonaceous foam. The resultant graphitized carbon powders have an interplanar spacing (d002) of graphite planes of less than 0.3370 nm. The powders preferably have an average particle size of from 2 to 200 &mgr;m. A thermally conductive composition includes the graphitized carbon powders in a matrix. The content of the powders is preferably 1 to 800 parts by weight relative to 100 parts by weight of the matrix. Thus, the graphitized carbon powders that have excellent thermal conductivity and a thermally conductive composition including such powders are provided.

Abstract: A thermally conductive molded article is produced by molding a conductive composition into a predetermined shape. The composition includes a polymer matrix and carbon powders. The carbon powders are obtained by graphitizing a polymeric material that has an aromatic ring on its main chain by heating. The carbon powders are aligned in a certain direction in the polymer matrix. Thus, the molded article can be produced easily and effectively that has excellent thermal conductivity in a given direction and that is suitable for use as a heat radiator, heat transfer member, or a component thereof in electronic hardware.

Abstract: A thermally conductive polymer composition includes polymer matrix such as thermoplastic resin or thermoplastic elastomer and a graphitized carbon fiber which serves as a thermally conductive filler. The graphitized carbon fiber is made from a mesophase pitch. The mesophase pitch is spun, infusibilized, carbonized, pulverized, and graphitized to form powdery graphitized carbon fibers. Preferably, the graphitized carbon fibers have a diameter of 5-20 &mgr;m, an average particle size of 10-500 &mgr;m, and a density of 2.20-2.26 g/cm3. The composition may be molded to form a thermally conductive molded article such as a thermally conductive sheet. The thermally conductive polymer composition and thermally conductive molded article have high thermal conductivity and transfer large amounts of heat from electric or electronic parts.