Abstract: A method of producing vapor grown carbon fibers is provided in which coal is utilized as a source of an iron catalyst, as a source of hydrocarbon and sulfur, or both. The method includes the steps of introducing pulverized coal into a furnace containing a gas selected from the group consisting of hydrogen, hydrocarbon, nitrogen, ammonia, helium, or mixtures thereof, and maintaining the gas at a temperature from about 1000.degree.-1175.degree. C. to form the fibers. The coal has a sulfur content of from 1 to 6% by weight and may comprise high volatile bituminous coal. The use of coal to produce vapor grown carbon fibers provides a significant cost advantage over other starting materials and also provides an environmentally safe use for high sulfur content coal.

Abstract: Carbon fiber with increased bulk density comprising vapor grown carbon fiber is provided. The preferred method of increasing the carbon fiber bulk density comprises mixing a vapor grown carbon fiber with a diameter of less than about 1 .mu.m and an initial bulk density of less than about 0.2 lb/ft.sup.3 with an aqueous-based solution, blending the mixture under high shear conditions, and drying the blended mixture. Upon drying, the mixture forms a carbon fiber mass with an increased bulk density having a final bulk density of at least about 3 lb/ft.sup.3. The increased bulk density carbon fiber pellets are ideally suited for use as reinforcing materials in rubber, plastic and the like. Preferably, the aqueous-based solution is a latex containing solution and latex is deposited on the fibers.

Abstract: A method is provided for forming a composite material and article using nanometer-size vapor grown carbon fibers. The preferred carbon fibers are characterized by diameters of substantially less than about one micrometer, and more typically less than about 0.2 micrometers, and are of the type formed by a continuous gas phase reaction. The polymeric matrix of the composite material is formed from a thermoplastic resin having a surface tension which is sufficiently low, so as to promote wetting of the surfaces of the nanometer-size carbon fibers. The thermoplastic resin is mixed with the carbon fibers and a solvent so as to granularize the mixture and thereby facilitate subsequent handling and mixing of the carbon fibers. Final mixing occurs at temperatures near the melting point of the thermoplastic resin and for a duration which is sufficient to ensure that the carbon fibers are adequately wetted by the thermoplastic resin, so as to provide adhesion between the fibers and the thermoplastic.

Abstract: In a preferred embodiment, an apparatus and method for forming carbon fibers in a gas phase reaction is disclosed wherein a reactor defines a reaction chamber with a closed end and an outlet and a reactant feed tube which extends generally axially therewithin. Gaseous reactants are injected into the reactor through an opening of the feed tube. The feed tube and chamber are constructed and arranged to define a passageway which is a gas flow path. The reactor includes purge means for intermittently and forcibly moving any fibers clogging the passageway out of the reactor, and means for intermittently oxidizing carbonaceous material in the passageway of the reactor. In use, a period of fiber formation is followed by a forced purge. Periodically, an oxidation purge is used to essentially cleanse the reactor.

Abstract: In a preferred embodiment, an apparatus and method for forming carbon fibers in a gas phase reaction is disclosed wherein a reactor defines a reaction chamber with a closed end and an outlet, and a reactant feed tube which extends generally axially therewithin. Gaseous reactants are injected into the reactor through an opening of the feed tube. Preferred reactants include methane, natural gas, hydrogen sulfide, ammonia, and an iron-containing compound dispersed in a carrier gas. The apparatus includes purge means for intermittently and forcibly moving any fibers clogging the reactor out of the reactor; and means for intermittently oxidizing carbonaceous material in the reactor. In use, a period of fiber formation is followed by one or more purge steps to essentially cleanse the reactor.