A method and precursor for making carbon fibers and the like comprising carbon black modified with at least one cyclic compound promoter. A source of the carbon black may be recycled materials such as recycled tires or recycled plastics. The carbon black is modified by attaching at least one cyclic compound promoter to the outer periphery of the carbon black.

The present disclosure relates generally to carbon fibers having high tensile strength and modulus of elasticity, as well as a process for the manufacture of such carbon fiber. The process comprises spinning a polymer/solvent solution into a solvent/water bath in the range of 78%-85% solvent, thereby producing a dense fiber structure, and subsequently carbonizing the polymer precursor fiber at a lower than typical carbonization temperature to form carbon fibers.

A method for manufacturing a carbon fiber bundle includes a stabilization process of subjecting an acrylic fiber bundle to a heat treatment within a range of 200° C. to 300° C. in an oxidizing atmosphere; a pre-carbonization process of performing a heat treatment within a range of 300° C. to 1,000° C. using a heat treatment furnace having at least one inert gas supply port on each of an incoming side and an outgoing side of the fiber bundle and at least one exhaust port between the incoming-side and outgoing-side inert gas supply ports, the heat treatment being performed with a temperature of an inert gas supplied being higher on the outgoing side than on the incoming side; and a carbonization process of performing a heat treatment at a temperature of 1,000° C. to 2,000° C. in an inert gas atmosphere, in which from a position at which an atmospheric temperature in the heat treatment furnace is 300° C., the position being closest to the outgoing side in a machine length direction, up to the inert gas supply port on the incoming side, a flow of an inert atmosphere within the heat treatment furnace in the pre-carbonization process consists only of a flow in a parallel flow direction with respect to a travel direction of the fiber bundle in the machine length direction. Provided is a method for manufacturing a carbon fiber bundle by which manufacturing can be performed continuously for a long time by preventing entry into a temperature zone causing deposition of a gasified decomposition product, such as tar, that is generated at the time of the pre-carbonization treatment in manufacturing of carbon fibers and that stays within the heat treatment furnace.

The invention relates to a method for the production of thermally stabilised melt spun fibres, in which polyacrylonitrile (PAN) fibres or PAN fibre precursors produced by melt spinning are treated in an aqueous alkaline solution which comprises in addition a solvent for PAN. Likewise, the invention relates to fibres which are producible according to this method.

The invention relates to melt spinnable copolymers of polyacrylonitrile (PAN) which are producible by means of copolymerisation of acrylonitrile with an alkoxyalkylacrylate. As additional comonomers alkylacrylates and vinyl esters may be considered. Likewise, the invention relates to a method for the production of fibres or fibre precursors, in particular carbon fibre precursors, by means of melt spinning, in which the mentioned copolymer is used. Furthermore, the invention relates to fibres produced in this way, in particular carbon fibres.

A carbon fiber has a fiber tensile strength in a range of 5.5 GPa to 5.83 GPa. The carbon fiber has a fiber tensile modulus in a range of 350 GPa to 375 GPa. The carbon fiber also has an effective diameter in a range of 5.1 μm to 5.2 μm. In a method of making a carbon fiber, PAN (poly(acrylonitrile-co methacrylic acid)) is dissolved into a solvent to form a PAN solution. The PAN solution is extruded through a spinneret, thereby generating at least one precursor fiber. The precursor fiber is passed through a cold gelation medium, thereby causing the precursor fiber to gel. The precursor fiber is drawn to a predetermined draw ratio. The precursor fiber is continuously stabilized to form a stabilized fiber. The stabilized fiber is continuously carbonized thereby generating the carbon fiber. The carbon fiber is wound onto a spool.

The invention relates to a method for thermally stabilizing melt-spun PAN precursors. For this purpose, the invention provides a continuous method for producing a thermally stabilized multifilament thread made of a meltable copolymer of polyacrylonitrile (PAN), wherein a pre-stabilized multifilament thread is thermally stabilized and in the process at least temporarily stretched. The invention additionally relates to a thermally stabilized multifilament thread which can be obtained according to a corresponding method and to a carbon fiber which is made of the correspondingly thermally stabilized multifilament thread.

A carbon-fiber-precursor acrylic fiber bundle which can smoothly pass through a flame-resistance impartation step and a carbonization step. The carbon-fiber-precursor acrylic fiber bundle has a high-density part as a portion thereof, wherein the high-density part satisfies the following requirements (A) and (B). Requirement A: The high-density part has a maximum fiber density ρ.sub.max of 1.33 g/cm.sup.3 or higher. Requirement B: The portion extending between an intermediate-density point and a maximum-density-region arrival point has an increase in fiber density of 1.3×10.sup.−2 g/cm.sup.3 or less per 10 mm of the fiber bundle length.

A method of preparing an acrylonitrile-based copolymer for a carbon fiber. The method includes: preparing a reaction solution including a (meth)acrylonitrile-based monomer and a first reaction solvent; adding a first portion of a radical polymerization initiator to the reaction solution to initiate polymerization; and adding a second portion of the radical polymerization initiator to the reaction solution when a polymerization conversion ratio is between 70 to 80%.

A method for producing a carbon fiber, the method comprising: (i) subjecting a continuous carbon fiber precursor having a polymeric matrix in which strength-enhancing particles are incorporated to a stabilization process during which the carbon fiber precursor is heated to within a temperature range ranging from the glass transition temperature to no less than 20° C. below the glass transition temperature of the polymeric matrix, wherein the maximum temperature employed in the stabilization process is below 400° C., for a processing time within said temperature range of at least 1 hour in the presence of oxygen and in the presence of a magnetic field of at least 1 Tesla, while said carbon fiber precursor is held under an applied axial tension; and (ii) subjecting the stabilized carbon fiber precursor, following step (i), to a carbonization process. The stabilized carbon fiber precursor, resulting carbon fiber, and articles made thereof are also described.