The present invention provides an amide acid oligomer which has specific composition and which is capable of providing a cured product having excellent physical properties, in particular, an excellent glass transition temperature, etc.

A method for manufacturing carbon fiber, the method includes: placing a carbon fiber as an anode in an electrolyte, wherein the electrolyte is nitric acid, sulfuric acid, phosphoric acid, acetic acid, ammonium bicarbonate, sodium hydroxide, or potassium nitrate; and performing a surface treatment, wherein a surface of the carbon fiber is oxidized by active oxygen generated by anodic electrolysis, and thereby oxygen-containing functional groups are introduced to the surface. The disclosure also provides a carbon fiber composite bottle, which includes a bottle body and a carbon fiber. The bottle body is a type III bottle or a type IV bottle. The carbon fiber surrounds the bottle body, the surface oxygen concentration of the carbon fiber is 5-35%, and the surface roughness of the carbon fiber is 5-25 nm.

Provided are tubular carbon fiber reinforced composite material and having excellent cylindrical bending strength and a golf club shaft using the same. This tubular carbon fiber reinforced composite material is formed by laminating and curing a straight layer and a bias layer. The straight layer comprises carbon fibers S coated with a sizing agent S and arranged in parallel in a direction of −20° to +20° with respect to the axis of the tubular body, and contains a thermosetting resin S. The bias layer comprises carbon fibers B coated with a sizing agent B and arranged in parallel in a direction of +25° to +65° with respect to the axis of the tubular body, and contains a thermosetting resin B. The carbon fiber reinforced composite material constituting the bias layer has an interlaminar shear strength of not less than 110 MPa. A cured product of the thermosetting resin S has an elastic modulus of not less than 4.0 GPa.

Disclosed herein is an electrically conductive sized fiber including a fiber and a sizing composition adhered to a surface of the fiber, wherein the sizing composition includes at least one sizing compound and a plurality of graphene oxide nanoparticles, The present disclosure also discloses fiber-reinforced resin composites, articles including fiber-reinforced resin composites and methods of making such electrically conductive sized fiber and articles therefrom.

An object of the present invention is to provide a carbon fiber which exhibits excellent strength development rate when used in a composite material. The present invention that solves the problems is a carbon fiber which simultaneously satisfies the following formulae (1) and (2):

Lc/d≤3  (1)

TS×d×Lc>6.0×10.sup.5  (2) wherein: Lc is an X-ray crystallite size (Å), d is a filament diameter (μm), and TS is a strand tensile strength (MPa).

A fibre-reinforced polymer composite comprising fibres bound within a solid polymer matrix, wherein at least some of the fibres are in contact with graphene, and wherein the composite changes electrical resistance when deformed.

A prepreg includes composition elements [A], [B], and [C] described below, [A] a reinforcing fiber, [B] a thermosetting resin, and [C] a thermoplastic resin. [C] is present on a surface of the prepreg, [B] contains a first curing agent [b1] and a second curing agent [b2], and the reinforcing fiber of [A] that crosses over a boundary surface between a resin region containing [B] and a resin region containing [C] and that is in contact with both resin regions is present.

The present invention relates to a fiber-reinforced plastic, including: a reinforcing fiber group containing reinforcing fibers; a thermosetting resin layer containing a first thermosetting resin; and a thermoplastic resin layer, in which the thermoplastic resin layer is provided as a surface layer of the fiber-reinforced plastic, an interface between the thermoplastic resin layer and the thermosetting resin layer is positioned inside the reinforcing fiber group, and the thermoplastic resin layer contains a dispersed phase of a second thermosetting resin.

Halogen-free, flame resistant and hydrolysis resistant polymer compositions are disclosed. The polymer composition of the present disclosure is also formulated to have improved electrical tracking resistance. The polymer composition contains a thermoplastic polymer, such as polybutylene terephthalate. The thermoplastic polymer is combined with a flame retardant that can include a phosphinate optionally in combination with a phosphite and/or a nitrogen-containing synergist. In order to improve electrical tracking resistance, one or more electrical resistance agents are added to the polymer composition. The electrical resistance agent, for instance, can be a flexible polymer.

A fiber-reinforced fabric, composite materials formed from such fabrics, and methods of making the fiber-reinforced fabric or composite materials, are provided. The fabrics and composite materials demonstrate improved fatigue performance relative to conventional fiber-reinforced fabrics.