Abstract: A twisted FRP structure having sufficient strength and flexibility is produced by providing a rod member disposed centrally and twist a plurality of side strands twisted around the rod member in the same direction at a predetermined pitch. At least the side strand includes a composite strand having an FRP element from by impregnating fibers with an uncured thermosetting resin and a thermoplastic coating on such FRP element, the thermosetting resin being cured after the side strands are twisted around the rod member. The twisting pitch is not less than 25 times the outside diameter of the FRP element in the side strand.

Abstract: A porous isotropic carbon-carbon composite having a porosity of 25 to 85% and substantially isotropic mechanical strength, and containing 60% by weight or more of aggregate particles having an aspect ratio of 10 or smaller and reinforced in one direction with carbon fiber is provided.

Abstract: The process produces carbon bodies from coal tar pitch coke which have a strongly reduced or no irreversible thermal expansion in the temperature range of 1400.degree. to 2000.degree. C. Before shaping, a sulphonate, carboxylate or phenolate of an alkaline earth metal which is at least partially soluble in the binder is added to the mixing constituents which consist of particulate coke and a cokable binder as raw materials. After the mixing, shaping and firing, bodies are obtained which have only slight puffing upon graphitization.

Abstract: A process for manufacturing a carbon catalyst for use in NO.sub.x reduction with ammonia catalyzed by active carbons and active cokes is described. The new carbon catalyst exhibits improved catalytic activity and hence a higher yield in NO. In the manufacturing process, a mixture of ground, oxidized hard coal and binders is moulded, carbonized at temperatures between 700.degree. and 900.degree. C., and then activated with steam at a temperature of 800.degree. to 850.degree. C. for 45 to 100 minutes, until a degree of activation of 5 to 15% is obtained.

Abstract: A process for making a carbon-carbon composite having a combination of high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizable woven cloth are covered with petroleum or coal tar pitch and pressed at a temperature a few degrees above the softening point of the pitch to form a green laminated composite. The green composite is restrained in a suitable fixture and heated slowly to carbonize the pitch binder. The carbonized composite is then impregnated several times with pitch by covering the composite with hot pitch under pressure. The composites are given a heat treatment between each impregnation step to crack up the infiltrated carbon and allow additional pitch to enter the microstructure during the next impregnation cycle. The impregnated composites are then given a final heat treatment in the range 2500.degree. to 3000.degree. C.

Abstract: Carbon fiber precursors from pitchy materials are processed by applying thereonto an aqueous emulsion containing a single silicone oil or a mixture of silicone oils selected from polydimethyl siloxane, phenyl modified polydimethyl siloxane and aminoalkyl modified polydimethyl siloxane and having kinetic viscosity at 25.degree. C. of 100 centistokes or less, an alkanolamine salt of aliphatic monocarboxylic acid with 8-18 carbon atoms, and one or more non-ionic surfactants selected from polyoxyethylene alkylphenylethers polyoxyethylene alkylates, polyoxyethylene alkylaminoethers, and aliphatic monocarboxylic alkanolamides such that 0.1-5 wt % by solid deposit on fiber from this aqueous emulsion apply to the pitch fibers during any of the processes from the spinning and to the oxidizing.

Abstract: A carbon/carbon composite is produced by impregnating a primary-formed product consisting essentially of carbon fibers and a carbonized or graphitized matrix with a carboneceous pitch, heat-treating the thus-impregnated primary-formed product under hot isostatic pressing and carbonizing or graphitizing the thus heat-treated primary-formed product.

Abstract: A granular carbonaceous heat insulator comprising a carbon black pellet the surface of which is coated with a carbon layer having a dense structure is disclosed. This heat insulator is prepared by adhering a binder solution to a carbon black pellet, heating the resulting coating to remove a solvent from the binder solution and, at the same time, to cure the binder, and baking the carbon black pellet coated with the cured binder in a non-oxidizing atmosphere to carbonize the cured binder. Alternatively, the heat insulator is prepared by subjecting a carbon black pellet having specific characteristics to wet granulation in the presence of a binder solution to crush the carbon black pellet and, at the same time, to granulate the crushed pellet, thereby preparing a granulated carbon black pellet, followed by removal of the solvent from the prepared pellet, curing of the binder and baking of the cured binder in the same manner as that described above.

Abstract: This invention relates to porous polytetrafluoroethylene (hereinafter PTFE) materials having the property of rapid recovery and a method for producing these materials. The microstructure of the porous PTFE material consists of nodes interconnected by fibrils, substantially all of the fibrils having a bent or wavy appearance. Articles made from these materials are particularly suitable for use in the medical field, but are also useful in other areas such as filtration and fabric applications.

Abstract: A novel method is disclosed for producing specular surfaces, composed of pure carbon, on carbon-carbon composites of arbitrary weave configuration. The method utilizes a thin sheet of fine grained polycrystalline graphite as a stress-isolating interlayer between the composite substrate and the specular surface layer. The interlayer is bonded to the carbon-carbon substrate with a high char yield carbonizable adhesive. An outer layer of glassy carbon is then applied using a high char yield resin solution or (lacquer). The resulting assembly is then carbonized to convert all uncarbonized polymer to carbon. The interlayer prevents the propagation of the substrate carbon-carbon composite's crack structure to the glossy carbonized polymer surface thus formed, resulting in a high degree of specularity and zero gas permeability.

Abstract: An impregnating carbonizing process and apparatus which permit reduction in cost of consumable goods and can operate at a reduced cost and a heating and vacuum impregnating operation which requires a very long period of time can be performed on the outside of an expensive high pressure vessel to accomplish rapid carbonization and baking.

Abstract: A process is provided for producing non-woven fabrics in which adhered points supporting the non-woven fabrics structure are the same carbon materials with the component fibers and which is superior in strength, dimensional stability, heat-resisting property, chemical resistance, electric conductivity, etc.This process comprises mixing spun pitch fibers or insufficiently infusiblized pitch fibers with infusiblized pitch fibers or carbonized pitch fibers, shaping the mixture into a sheet or the like and thereafter carbonizing the shaped mixture in the atmosphere of an inert gas to mutually fix the component fibers by utilizing the adhering property of the spun pitch fibers or the insufficiently infusiblized pitch fibers during the carbonization.

Abstract: A method of making an elongated structural element of fiber reinforced plastic material with a solid walled casing. A hollow tubular casing is generally simultaneously filled with elongated strands of continuous fibrous reinforcement and plastic material and solidified. The casing is part of the final product. An internal casing may also be used where the fiber reinforced plastic is between the internal and external casings. The elongated structural element may be initially shaped prior to solidification or after reheating reshaped into another shape such as a helical coil or spring.

Abstract: The invention is concerned with a high-density adsorbent comprising a compacted mass of high surface area carbon particles bound together with a binder and defining a network of substantially unobstructed micropores, the mass of carbon particles having been compacted under a pressure sufficient to cause a reduction of about 50 to about 200% in bulk volume of the mass and a corresponding increase of about 50 to about 200% in density, thereby providing a gas storage capacity increase of about 20 to about 100% over that of the high surface area carbon particles in loose or uncompacted form. The high-density adsorbent according to the invention is particularly useful in adsorption storage systems for low-pressure storage of compressed natural gas.

Abstract: The present invention resides in improved graphite nipples which are suitable for connecting graphite electrodes. The graphite nipples are prepared by adding mesophase pitch-based carbon fibers into a typical nipple extrusion blend.

Abstract: A process of making carbon-bonded refractory shapes by preparing a mix of refractory materials, pitch or tar and a binder resin, molding the mix into shapes and hardening the shapes. A starting mix is used which, based on the added quantity by weight of pitch or tar, contains 1 to 10 weight % of hollow fibers. The refractory shapes have the advantage that they exhibit less cracking, and hardly any, or even no, breaking occurs during their fabrication.

Abstract: A carbonized composite foam having a density less than about 50 mg/cm.sup.3 and individual cell sizes no greater than about 1 .mu.m in diameter is described, and the process of making it.

Abstract: The invention relates to a method for forming twin-wall polycarbonate sheets into desired arcuate forms to be used, for example, as awnings. The method is distinguished from known forming techniques which are generally not effective in forming the polycarbonate sheets hereinafter described.The method generally includes preheating a portion of the polycarbonate sheet within a heating chamber, engaging the sheet with the mould which is pivotally mounted to the frame of an apparatus within the heating chamber, frictionally restraining the movement of the sheet with respect to the frame at a position spaced from the mould, and outside the heating chamber, and pivoting the mould so as to form the sheet.The present invention generally overcomes the difficulties in forming twin-walled polycarbonate sheets thereby allowing this material to be used in place of other conventional awning materials such as fibreglass and corrugated iron.

Abstract: Graphite blocks are produced by a process wherein one or plural polymer films having a thickness of from 1 to 400 .mu.m and selected from aromatic polyimides, aromatic polyamides and polyoxadiazoles are heat treated to obtain carbonaceous films. A plurality of the carbonaceous films are hot pressure under certain conditions to obtain thick graphite blocks. The blocks have a remarkably improved rocking characteristic and are useful as radiation optical elements such as X-ray or neutron ray monochromators or filters. The blocks may be curved to obtain bent-type graphite articles.

Abstract: The present invention relates to physical chemistry.The material is made as a three-dimensional matrix with a pore volume of from 0.2 to 1.7 cm.sup.3 /g. The matrix is formed by bent layers of carbon of 100-10,000 .ANG. thickness and 100-10000 .ANG. radius of curvature. The true density of the material according to the present invention is 1.80-2.10 g/cm.sup.3, its X-ray density is 2.112-2.236 g/cm.sup.3, the pore size distribution has its maximum within the range of 200-2,000 .ANG..The present invention can be useful in, for example, in the production of catalysts.

Abstract: A process for the production of a composite material with matrix and reinforcing fibers of carbon. The process comprises: (a) forming a porous substrate (2) of carbon fibers; (b) covering the surface of each fiber wih a fine silicon carbide coating (6) by chemical vapor deposition; (c) shaping the substrate; (d) embedding the substrate in a carbon matrix (4) containing at most 20% by weight siliconcarbide; (e) covering the outer surface of the matrix with an outer silicon carbide covering (10) which contains cracks (12); and (f) filling the cracks in the outer covering with at least a borosilicate glass (16).

Abstract: A process for producing a high density, high strength carbon-carbon composite which does not require high cost secondary reinforcement treatment. This process comprises impregnating an aggregate such as a bundle of a carbon fiber with a liquid dispersion of a carbonaceous material of specified size of a fine powder or a short fiber of carbonaceous material to form a reinforcement material of a carbon fiber having the fine powder or the short fiber of a carbonaceous material distributed on the surface as well as in the inside of said bundle of a carbon fiber, and impregnating said aggregate of a carbon fiber with one or more liquid carbonaceous material selected from the group consisting of a phenolic resin, a furan resin and a pitch and carbonizing the impregnated bundle of a carbon fiber, and if necessary, graphitizing the carbonized product.

Abstract: A process and apparatus for the preparation of green briquettes for the production of silicon or silicon carbide or ferrosilicon in electric pit furnaces, quartz sand, a carbon carrier and a bituminous binder being mixed together, the mixture being shaped into blanks from which the green briquettes are formed by heat treatment. The process is performed with the use of blanks which are free from melted bituminous caking coal and whose specific weight is made greater than the bulk density of quartz sand by adjustment of the proportions of the mixture and by compacting. The blanks are introduced for the heat treatment into a heated rotating drum furnace whose lower part is filled with quartz sand to an extent such that the heat treatment proceeds in a dip bed of quartz sand.

Abstract: Process for producing a fiber reinforced plastics linear material like a tension member for optical communication cables. A groove capable of accomodating an optical fiber is formed in the outer surface of the tension member. In accordance with the conventional method, the groove is necessarily formed in parallel along the axial direction of the tension member and, therefore, if the tension member is bent in the state that the optical fiber is placed in the groove, a force due to bending is applied directly to the optical fiber and the transmission loss of the optical fiber is increased.

Abstract: Thin-walled catheters are provided which have an elongated fuseless polymeric tube that is made from a single tube of extruded polymer. The elongated fuseless polymeric tube includes a body portion that had been subjected to a high temperature zone in order to solid state polymerize and enhance the mechanical stability, burst strength and kink resistance of the body portion. Also included is a tip portion of the elongated fuseless polymeric tube which was subjected to a low temperature zone to retain the initial properties of extruded polymer.

Abstract: Disclosed herein is an electrode substrate for fuel cells comprising two porous, carbonaceous layers, each having a number of elongated holes for feeding reactant gases into a fuel cell which are provided near the center of the thickness in said layer, and a gas impermeable, carbonaceous separator, interposed between said layers and having a number of elongated holes for flowing coolant which are provided near the center of the thickness in the separator. The porous layer is either a uniformly porous, carbonaceous monolayer, or has a two-layer structure comprising a more porous layer, a less porous layer and elongated holes for feeding reactant gases provided between said more porous layer and said less porous layer, the less porous layer having a bulk density larger than that of the more porous layer. There are also provided according to the invention processes for preparing such an electrode substrate for fuel cells.

Abstract: A process for producing a carbon product having coarse and dense structures by carbonizing moldings of a mixture of one or more types of organic polymer substance, asphalt pitches, dry distilled pitches to obtain a dense structure carbon by carbonizing in an inert gas atmosphere or with a mixture of fine particle graphite powder as required, and porous organic polymer produced in point contact between the particles by solubilizing the surface layers of the organic polymer particles to obtain coarse structure carbon by sintering in particle state by carbonizing in an inert gas atmosphere, in an inert gas atmosphere after solidification to integrally mold organic liquid composition remaining high carbon residue in a composite composition, and carbonizing the composite composition in an inert gas atmosphere.

Abstract: Carbides, nitrides or carbonitrides of elements from the main groups III and IV and sub-groups III, IV, V and VI of the periodic system of elements are prepared by(i) reacting compounds of the formula MX.sub.m or R.sub.n MX.sub.m-n with a reactive hydrocarbon-containing compound or a mixture of compounds which is polymerizable and which contains a reactive compound with one C--OH-group in whichM is an element of the main group III or IV or sub-group of III, IV, V or VI of the periodic system of elements,X is a halogen,R is hydrogen or alkyl or aryl,m is an integer corresponding to the valency stage of M,n is an integer from 1 to one less than the velency stage of M, and(ii) thermally decomposing the resulting product from (i) to the corresponding carbide or to the corresponding nitrides or carbonitrides with further nitridation.

Abstract: A method for making a carbon-graphite component, such as a fuel cell substrate, suited for use in an electrochemical cell includes forming a precursor sheet structure comprising a resin, fibers that are graphitizable, and an inorganic compound containing boron and oxygen. Various details of the method are developed that effect the carbon yield of cellulose fibers used for the precursor sheet and the thermal and the electrical conductivity of the component. In one embodiment, the inorganic compound of boron and oxygen is boric acid.

Abstract: An edge guard and method of manufacture are disclosed wherein plastic is extruded onto wires which may be individual wires taken from reels or a wire mesh screen.

Abstract: An apparatus for producing a curved tube, the apparatus comprising an extruder for extruding a tube having a wall including a first portion having a thickness, and a second portion diametrically opposite the first portion and having a thickness less than the thickness of the first portion, and rollers for forming the tube into a curve with the first portion being radially outward and with the second portion being radially inward so that the thickness of the first portion becomes substantially equal to the thickness of the second portion.

Abstract: A graphitic or carbonaceous molding comprising graphite powder and a mesophase-containing pitch is obtained by suspending graphite powder in a tar, heating the suspension while blowing an inert gas therein to form the mesophase-containing pitch on the graphite particles to obtain carbonaceous precursors and molding/carbonizing or graphitizing the carbonaceous precursors.

Abstract: A hollow body (e.g. a container) as well as a method and an apparatus for its manufacture in which an axially directed wall of the body primarily is made of oriented and/or crystallized plastics material. A tubular preform (10d) is fixed in a circumferential region (13d) in the vicinity of the mouth edge (14d) of the preform between mechanical forming devices (30,40), after which the devices, during continued clamping of the circumferential region, are displaced in the axial direction of the preform relative to a mandrel (50). Thus, the mandrel is displaced into the preform during simultaneous expansion thereof and the material is oriented and/or crystallized. In a preferred embodiment there is made a certain compensation of the stretching forces, which arise in the material when inserting the mandrel, by applying a force to the bottom of the preform by a bottom support (75).

Abstract: A method is disclosed for making plastic products that enables adjacent portions thereof to be easily folded into juxtaposed relationship. A hinge is formed by utilizing an angled or curved cutting tool to create a continuous slit which in a preferred configuration (when viewed in profile) is generally L-shaped so that it extends from one surface of the product to a first location that is within the products' body and then extends therein from the first location to a second location also within the thickness of the body. The slit opens onto the one surface and thereby forms a flexible bridge integral with those portions of the product adjacent thereto, the bridge permitting such adjacent portions to be flexibly folded into juxtaposed relationship.

Abstract: A process for producing an acoustic diaphragm of carbonaceous material including the steps of impregnating nonwoven fabric or woven fabric of carbon fiber having a high degree of elasticity with a thermosetting resin, thermally molding it into a diaphragm shape, calcining the shaped fabric in an inert gas atmosphere to obtain a porous carbon molding, heating the porous molding to a uniform temperature, and depositing vapor phase, thermally decomposed carbon upon a surface of the porous molding. The deposited carbon is generated by thermal decomposition of a hydrocarbon-containing material introduced together with a carrier gas. The process produces an acoustic diaphragm having a dense surface layer of carbonized fiber-carbonized thermosetting resin-thermally decomposed carbon, and a porous interior of carbonized fiber bonded together by carbonized resin and the thermally decomposed carbon.

Abstract: A gasket is formed with a mounting portion which is generally cylindrical, and provides an anchoring projection extending radially from the outer side thereof. A sealing projection is joined to the mounting portion by a hinge section. The sealing projection is placed in compression when the gasket is formed into a circle, and becomes bistable. In one position of stability, the sealing projection is substantially aligned with the mounting portion, and in the other position of stability, the sealing projection is located generally within the mounting portion. The gasket is positioned around a core, with the sealing projection aligned with the mounting portion, and is cast into an opening provided by the material of the manhole riser. In such position, the sealing projection is partially embedded within the material of the riser. Prior to installation of a sewer pipe, the sealing projection is manually released from the material of the riser and is pushed through to its other position of stability.

Abstract: A process for producing almost perfect graphite films and fibers at lower graphization temperatures wherein a film or fiber of a polymer selected from a defined group is subjected to a preliminary heat treatment at a temperature of 400.degree. to 700.degree. C., under tension, in vacuo or in an inert gas, and then heat treating the film or fiber at a temperature of at least 1600.degree. C. in vacuo or in an inert gas, to graphitize the film or fiber. The process can be modified to produce graphite films having excellent electric conductivity and mechanical properties, by heat treating a polymer selected from a second defined group at a temperature of at least 1800.degree. C. in vacuo or in an inert gas, impregnating the film with a binder component, and then heat treating the impregnated film at a temperature of not more than 1400.degree. C.

Abstract: Applicator syringe for a dental compound, with a syringe body (1) tapering into a thin discharge tube (3) and with a piston (5) displaceable in it, the applicator syringe being intended for once-only use. To avoid the need for special actuating tools, but make easy use possible, the effective cross-sectional surface is very small, in particular with a ratio of the useful stroke to the diameter of the syringe piston of at least approximately 10. So that the syringe can nevertheless be filled easily, the diameter of the cylindrical space in the rear portion of the latter is larger than the piston diameter. The syringe body (1) is first produced in a straight form and only thereafter is the discharge tube (3) bent.

Abstract: A preformed yarn useful in forming fiber-reinforced carbon composite articles is disclosed which includes a core of a multiplicity of inorganic reinforcing fibers, a mixed powder provided in the interstices between the fibers and including a finely divided carbonaceous binder pitch and a finely divided coke, and a flexible sleeve formed of a thermoplastic resin and surrounding the core.

Abstract: A flat stock strip of thermoplastic material is passed through a heating station in contact with the edges of longitudinally oriented heated knife blades to heat soften the stock strip along narrow longitudinal lines to define localized fold lines for the stock strip. The strip is fed sequentially through a prebending device and a chilled forming die to set the reformed strip at the fold lines. Preferably the knife blades and any strip contact surfaces of the prebending device and the chilled forming die are PTFE covered to eliminate scratching of the thermoplastic stock strip material during heating, reforming and cooling.

Abstract: The specification describes and claims a method of making therapeutic rings from a curable silicone rubber based composition. The rings are capable of controlled release of the therapeutic agent in the human or animal body. The method includes the steps of:(i) extruding a first composition comprising a therapeutic agent and a first elastomer-forming silicone composition to provide a core;(ii) extruding a second composition comprising a second elastomer-forming silicone composition to provide a sheath enclosing the core;(iii) bringing together end portions of a piece of extruded core and sheath to form a ring,(iv) effecting crosslinking of the extruded core, and(v) effecting crosslinking of the extruded sheath.

Abstract: A closure system including a cap and a container, the cap including a top wall, a depending skirt having a bottom end and an annular projection integral with the bottom end of the skirt and having a curled free end portion which has grooves formed by threads in the neck when the cap is pressed on the container in sealed relationship.

Abstract: A process for producing a carbon product having coarse and dense portions, the process including producing an integral porous carbon having high strength and uniform porosity distribution with dense structure carbon moldings. The carbon moldings are produced by calcining in an inert gas atmosphere a composite of (a) a green molding, a precarbonized material or a carbide and (b) chlorinated vinyl chloride resin particles, the chlorinated vinyl chloride resin producing, when carbonized in an inert gas atmosphere, a coarse structure. Dense carbon is formed by carbonizing the green molding, precarbonized material or carbide. Thus, the carbon product has coarse and dense portions.

Abstract: Process for producing carbon molecular sieves for separating oxygen and nitrogen by treating a carbonaceous product with inert gas and steam in a vibrating oven and further treating said product with benzene at a high temperature in a vibrating oven to thereby narrow the existing pores.

Abstract: A method is disclosed for forming a net-like structure from a suitable material, such as metal or a synthetic polymer. The structure avoids the problems of low tear strength at the joints in the mesh and enables novel shapes and designs to be formed that are not possible to make by other methods. The method comprises the steps of forming a planar web from a suitable material in a plastic state, the forming providing for the planar web to have a substantially flat parting plane, the planar web having an expandable pattern of strands and strand joints with apertures therebetween, and expanding the planar web by forcing the exterior and interior of the web apart in a direction generally perpendicular to the planar web, to form a three-dimensional net-like structure.

Abstract: A process for treating high sulfur petroleum coke to inhibit puffing is disclosed wherein particles of the petroleum coke are contacted, in the absence of a binder, with a compound containing an alkali or alkaline earth metal selected from the group consisting of sodium, potassium, calcium and magnesium, at an elevated temperature above that at which the alkali or alkaline earth metal compound begins to react with carbon, but below the temperature at which the coke particles would begin to puff in the absence of the compound. The coke particles are maintained at the elevated temperature for a sufficient period of time to permit the reaction to proceed and allow products of reaction to penetrate into the particles and form an alkali-or alkaline-earth-metal-containing deposit throughout the mass of the particles; and then cooling the so-treated coke particles.

Abstract: Porous anodic aluminum oxide sheet, when removed from its aluminum metal substrate, is a useful filter but rather brittle. It can be formed into a desired shape by flexing in a direction transverse to the direction in which the metal substrate was rolled. Or the sheet can be wetted to make it more flexible and then formed by flexing in any direction. The formed sheet can be heat-set in a desired shape by heating at 200.degree. C. to 650.degree. C.

Abstract: In combination, a container and a linerless cap and a method of forming the cap. In the method the cap is molded from plastic and includes a top well, an outer depending skirt and an internal depending substantially annular wall having an upper end integral with and depending from the top wall and a lower free end. Thereafter the free end is engaged by a curling tool to progressively turn the free end away from the internal wall to curve the free end into a curvilinear compressible and resilient free end adapted to be engaged for sealing. The engageable free end of the seal can have a coil, O, U, J or quarter round cross sectional shape and can be a rim, plug or corner seal.

Abstract: The invention relates to a process for preparing mineral and in particular, carbon-containing membranes on a porous mineral support. According to the process, at least one layer of a stable emulsion of mineral particles in a solution containing a thermosetting resin is deposited on a permeable, porous, mineral support. The resin undergoes a polycondensation treatment followed by coking, and the coke formed insures the mechanical connection of the mineral particles both to one another and to the support. The membranes produced according to the invention can be used in separating processes, particularly in microfiltration and ultrafiltration.

Abstract: Carbon fibers may be made by a process comprising:overwrapping a multifilament polyacrylonitrile tow with a thread of material to maintain the tow as an integral bundle, followed bystabilizing said tow by heating in an oxidizing atmosphere at a temperature between about 180.degree. and about 400.degree. C., thereby oxidizing the filaments comprising said tow, followed bycarbonizing the tow thus stabilized by heating at a temperature sufficient to effect carbonization, thereby forming a carbon fiber.The carbon fibers may be used to make reinforced composites in thermoplastic or thermosetting matrix resins, particularly prepreg.