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 of manufacturing a graphene fiber is provided. The method includes preparing a source solution including graphene oxide, supplying the source solution into a base solution containing a foreign element to form a graphene oxide fiber, separating the graphene fiber from the base solution and cleaning and drying to obtain the graphene oxide fiber containing the foreign element, and performing thermal treatment to the dried graphene oxide fiber containing the foreign element to form a graphene fiber doped with the foreign element. Elongation percentage of the graphene fiber is adjusted by concentration and spinning rate of the source solution.

A method of manufacturing a graphene fiber is provided. The method includes preparing a source solution including graphene oxide, supplying the source solution into a base solution containing a foreign element to form a graphene oxide fiber, separating the graphene fiber from the base solution and cleaning and drying to obtain the graphene oxide fiber containing the foreign element, and performing thermal treatment to the dried graphene oxide fiber containing the foreign element to form a graphene fiber doped with the foreign element. Elongation percentage of the graphene fiber is adjusted by concentration and spinning rate of the source solution.

A multi-composition fiber is provided including a primary fiber material and an elemental additive material deposited on grain boundaries between adjacent crystalline domains of the primary fiber material. A method of making a multi-composition fiber is also provided, which includes providing a precursor laden environment, and promoting fiber growth using laser heating. The precursor laden environment includes a primary precursor material and an elemental precursor material.

A method of making a carbon nanotube composite yarn, the method including growing floating carbon nanotubes in a reactor, forming a mat of carbon nanotubes from the floating carbon nanotubes, a deposition step including depositing secondary particles on at least a portion of the mat of carbon nanotubes to provide a carbon nanotube composite mat, and a densification step including densifying the carbon nanotube composite mat to provide a carbon nanotube composite yarn.

A fiber comprises a bulk material comprising: one or more of carbon, silicon, boron, silicon carbide, and boron nitride; and a metal or metal alloy whose affinity for oxygen is greater than that of the bulk material. At least a first portion of the metal or metal alloy is present at the entrance to grain boundaries at the surface of the fiber and within the fiber to a depth of at least 1 micron from the fiber surface.

A method of improving a fiber comprises heating a fiber in an inert atmosphere to 900-1300 C for sufficient time to allow at least some of a metal or metal alloy, placed on the fiber, to diffuse and/or flow into and along grain boundaries to a depth of at least 1 micron. The metal or metal alloy has a greater affinity for oxygen than that of the fiber bulk material.

Graphene has been used in nanocomposites as constituents/doping in plastics or epoxy providing dramatic enhancement of the mechanical properties but have not progressed past the laboratory level novelty. This invention can provide a graphene based composite structure with a density less that 1.9 g/cm.sup.3 for a fiber, yarn, rope or cable and a density less that 1.5 g/cm.sup.3 for a sheet both structure have tensile and shear strength greater than either Aluminum or Steel; thus providing a graphene material that is both much lighter and stronger.

Graphene has been used in nanocomposites as constituents/doping in plastics or epoxy providing dramatic enhancement of the mechanical properties but have not progressed past the laboratory level novelty. This invention can provide a graphene based composite structure with a density less that 1.9 g/cm.sup.3 for a fiber, yarn, rope or cable and a density less that 1.5 g/cm.sup.3 for a sheet both structure have tensile and shear strength greater than either Aluminum or Steel; thus providing a graphene material that is both much lighter and stronger.

A fiber comprises a bulk material comprising one or more materials selected from the group consisting of carbon, silicon, boron, silicon carbide, and boron nitride; and a metal whose affinity for oxygen is greater than the affinity for oxygen of any of the one or more materials. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium. At least a first portion of the metal may be present in un-oxidized form at the entrance to and/or within grain boundaries within the fiber. A method of improving at least one of the strength, creep resistance, and toughness of a fiber comprises adding to a fiber, initially comprising a bulk material having a first affinity for oxygen, a metal that has a second affinity for oxygen higher than the first affinity. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium.

An artificial turf fiber comprising at least one monofilament, each monofilament comprising a cylindrical core and a cladding. The core comprises a core polymer and threadlike regions formed by a thread polymer and embedded in the core polymer. The cladding is formed by a cladding polymer surrounding the core. It has a non-circular profile and is miscible with the core polymer.