A method for making carbon fiber in which the tensile strength of carbon fiber is increased without dehumidifying the ambient air that enters every oxidation oven in a multiple oxidation oven system. A positive effect on tensile strength is provided when ambient air entering only the first oven in a series of oxidation ovens is dehumidified. In addition, the ambient air entering the last oven is not dehumidified when one or more of the preceding oxidation ovens is operated with dehumidified air.

Provided is a method of producing a carbon fiber, the method including: a) adding an acrylonitrile-based polymer solution to a solution containing a glycol-based compound having a boiling point of 180 to 210° C. to precipitate an acrylonitrile-based polymer; b) melt spinning the acrylonitrile-based polymer to obtain a spun fiber; and c) performing stabilization and carbonization on the spun fiber to obtain a carbon fiber.

A method of manufacturing a stabilized fiber bundle is described, which includes subjecting an acrylic fiber bundle aligned, to a heat treatment in an oxidizing atmosphere, with the acrylic fiber bundle being turned around by a guide roller placed on each of both ends outside a hot air heating-type oxidation oven, wherein an air velocity Vm of first hot air sent through a supply nozzle(s) disposed above and/or under a fiber bundle travelled in the oxidation oven, in a substantially horizontal direction to a travelling direction of the fiber bundle, and an air velocity Vf of second hot air flowing in a fiber bundle passing a flow channel in which the fiber bundle is travelled that satisfies expression 1)

0.2≤Vf/Vm≤2.0   1)

to produce a high-quality stabilized fiber bundle and a high-quality carbon fiber bundle at high efficiencies without any process troubles.

A method of producing carbon nanofibers is disclosed that substantially impacts the carbon nanofibers' chemical and physical properties. Such carbon nanofibers include a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1 nm and oriented parallel to an axis of a respective carbon nanofiber, the semi-graphitic carbon material also being characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms, the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms. The method of manufacture includes, for example, preparing a Polyacrylonitrile (PAN) based precursor solution, providing the PAN-based precursor solution to a spinneret and then performing an electro-spinning operation on the PAN-based precursor solution to create the one or more PAN-based nanofibers. The electro-spinning operation includes passing the PAN-based precursor solution from the spinneret to a collector at a distance between 1 cm to 30 cm while providing an Alternating Current (AC) voltage between the spinneret and the collector, the AC voltage including a frequency ranging from 20 Hz to 100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V. Afterwards, post-electro-spinning operations, stabilizing treatments and pyrolysis treatments are performed.

A method manufactures a flame-retardant fiber bundle by flame retarding treatment of a polyacrylonitrile-based precursor fiber at 200-300° C. in an oxidizing atmosphere, wherein a fiber bundle is caused to travel so as to sequentially pass between an nth roller and an (n+1)th roller (n being an integer of at least 1 and no more than [m−1]) in a roller group formed from m (m being an integer of 3 or greater) contiguously set rollers, the roller axes of the m continuously set rollers being parallel to each other and perpendicular to the direction of travel of the fiber bundle, the roller diameter being 5-30 mm, and the specific gravity of the fiber bundle being 1.20-1.50.

The present disclosure relates to a process for producing carbon fibers utilizing a salt of an organic cation containing C═N imine group, and carbon fibers produced by such process.

Provided is an acrylonitrile-based copolymer for a carbon fiber which includes a sulfonate-based monomer unit, a carboxylic acid-based monomer unit, and an acrylonitrile-based monomer unit, and the acrylonitrile-based copolymer for a carbon fiber includes the sulfonate-based monomer unit at 0.55 to 1.55 mol %, and the carboxylic acid-based monomer unit at 0.60 to 1.40 mol %.

The present disclosure relates to a metal nanoparticles impregnated activated carbon fiber for removing harmful substances, and a method of manufacturing the same. A method of manufacturing a metal nanoparticles impregnated activated carbon fiber for removing harmful substances according to the present disclosure includes an activation step of manufacturing an activated carbon fiber by heat-treating a precursor including a waste carbon fiber under a mixed atmosphere of activation gases including water vapor, carbon monoxide, nitrogen, argon, helium, or combinations thereof, and a metal containing step of containing metal in the activated carbon fiber. According to the present disclosure, a carbonization process is unnecessary since a precursor including the waste carbon fiber is used, and the metal nanoparticles impregnated activated carbon fiber may have remarkably improved adsorptive power compared to an activated carbon fiber with the same specific surface area by controlling the micropore distribution.

A method of producing carbon fibers includes the step of providing polyacrylonitrile precursor polymer fiber filaments. The polyacrylonitrile precursor filaments include from 87-97 mole % acrylonitrile, and less than 0.5 mole % of accelerant functional groups. The filaments are no more than 3 deniers per filament. The polyacrylonitrile precursor fiber filaments can be arranged into tows of at least 150,000 deniers per inch width. The arranged polyacrylonitrile precursor fiber tows are stabilized by heating the tows in at least one oxidation zone containing oxygen gas and maintained at a first temperature T.sub.1 while stretching the tows at least 10% to yield a stabilized precursor fiber tow. The stabilized precursor fiber tows are carbonized by passing the stabilized precursor fiber tows through a carbonization zone. Carbon fibers produced by the process are also disclosed.

A carbon material precursor comprises an acrylamide-based polymer having a weight-average molecular weight of 10,000 to 2,000,000 and a polydispersity of the molecular weight (weight-average molecular weight/number-average molecular weight) of 5.0 or less.