A fiber-reinforced composite material includes a matrix resin, and reinforcing fibers, in which the matrix resin includes a polyaryl ketone resin and a resin having a nitrogen atom in a repeating structural unit. A surface of the fiber-reinforced composite material includes a portion in which a contact angle with water is 60° or less.

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.

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.

An impregnation liquid is provided, which includes (A) phenolic resin, (B) diazonaphthoquinone-based compound or a derivative thereof, (C) ionic compound, and (D) organic solvent. The weight of (A) phenolic resin and the weight of (B) diazonaphthoquinone-based compound or a derivative thereof have a ratio of 0.2:0.8 to 0.9:0.1, and the weight of (C) ionic compound and the total weight of (A) phenolic resin and (B) diazonaphthoquinone-based compound or a derivative thereof have a ratio of 0.2:1 to 1.4:1. The impregnation liquid can be used to form an activated carbon layer to wrap and to be directly in contact with the surface of a mesh.

The invention relates to a ball game racket frame (12) including a head portion (14), a shaft portion (18) and a grip portion (20). The ball game racket frame (12) comprises a fiber composite material having fibers embedded in a matrix. At least 5% of the fibers are natural fibers in at least one cross-section (28, 28a, 28b, 28c, 28d, 28e) of a portion of the ball game racket frame (12).

The invention further relates to a ball game racket frame (12) in which the proportion of natural fibers in at least one cross-section (28b, 28c, 28d, 28e) of the shaft portion (18) and/or the grip portion (20), respectively, is greater than the proportion of natural fibers in at least one cross-section (28, 28a) of the head portion (14).

The invention further relates to a method for manufacturing such ball game racket frames (12).

The present invention relates to a process for impregnating a fibrous substrate consisting of long fibers by a liquid (meth)acrylic mixture mainly containing methacrylic and/or acrylic components. The invention also relates to such a (meth)acrylic mixture and its composition, said (meth)acrylic mixture comprising a (meth)acrylic syrup and an aqueous dispersion of radical initiator. The invention also relates to a process for manufacturing mechanical parts or structured elements or articles made of composite material by impregnating the fibrous substrate with the (meth)acrylic mixture then polymerizing said (meth)acrylic mixture, and also such parts obtained according to said manufacturing process and used in varied fields such as the automotive industry, aeronautics, or else construction.

A method for surface preparation of composite substrates prior to adhesive bonding. A curable surface treatment layer is applied onto a curable, resin-based composite substrate, followed by co-curing. After co-curing, the composite substrate is fully cured but the surface treatment layer remains partially cured. The surface treatment layer may be a resin film or a removal peel ply composed of resin-impregnated fabric. After surface preparation, the composite substrate is provided with a chemically-active, bondable surface that can be adhesively bonded to another composite substrate to form a covalently-bonded structure.

Provided is a prepreg including: a fiber layer containing unidirectionally arranged carbon fibers impregnated with a first thermosetting resin; and a resin layer disposed on at least one side of the fiber layer and containing a second thermosetting resin and a thermoplastic resin that is insoluble in the second thermosetting resin. The prepreg is configured such that the areal weight of fibers and the weight fraction of resin in the prepreg are 120 to 300 g/m.sup.2 and 25 to 50 mass %, respectively, and in the case where a plurality of prepregs are laid up, and the coefficient of interlayer friction is measured every 10° C. in a temperature range of 40 to 100° C. at a pull-out speed of 0.2 mm/min under a perpendicular stress of 0.8 bar, the temperature at which the coefficient of interlayer friction is 0.02 or less is present within a temperature range of 40 to 100° C. The prepreg exhibits high impact strength when formed into a fiber-reinforced plastic suitable for an aircraft structural member, and the prepreg also has excellent drapeability when a prepreg laminate is made to conform to a three dimensional shape.

The present invention relates to a resin composition containing a compound having a maleimido group, a divalent group having at least two imido bonds and a saturated or unsaturated divalent hydrocarbon group.