An object of the present invention is to provide a prepreg and a laminate for producing a laminate suitable as a structural material, which have excellent joining strength and can be firmly integrated with another structural member by welding. The present invention provides a prepreg including the following structural components: [A] reinforcing fibers, [B] a thermosetting resin, and [C] a thermoplastic resin, wherein [A] has a surface free energy, measured by a Wilhelmy method, of 10 to 50 mJ/m.sup.2, [C] is present on a surface of the prepreg, and the reinforcing fibers [A] are present, which are included in a resin area including [B] and a resin area including [C] across an interface between the two resin areas.

A carbon fiber-reinforced molded article includes an arranged composite material and a cured resin product. The composite material includes a carbon fiber bundle and carbon nanotubes. The carbon fiber bundle is in which a plurality of continuous carbon fibers are arranged. The carbon nanotubes adhere to respective surfaces of the carbon fibers. A modulus of elasticity obtained by conducting a three-point bending test with a cushioning material is smaller than a modulus of elasticity obtained by conducting the three-point bending test without the cushioning material.

Provided are a composite material that adequately obtains the effect of carbon nanotubes, a prepreg in which the composite material is used, a carbon-fiber-reinforced molded article having greater resistance to the progression of the interlayer peeling crack, and a method for manufacturing the composite material. A composite material includes a carbon fiber bundle in which a plurality of continuous carbon fibers are arranged, carbon nanotubes adhering to respective surfaces of the carbon fibers, and a plurality of fixing resin parts partly fixing the carbon nanotubes on the surfaces of the carbon fibers, where the fixing resin parts cover 7% or more and 30% or less of the surfaces of the carbon fibers to which the carbon nanotubes adhere.

The present disclosure discloses a continuous electrophoretic deposition modified carbon fiber reinforced multi-matrix composite and a preparation method thereof, composing of a carbon fiber with a volume fraction of 30-55%, an inorganic powder with a volume fraction of 3-25% and a matrix with a volume fraction of 20-67%, wherein the inorganic powder is wrapped on the surface of the carbon fiber filament or embedded in the carbon fiber bundle, and the concentration gradually decreases from the fiber filament to the surface of the fiber bundle. The preparation method of the composite is as follows: (1) pretreating the carbon fibers; (2) preparing a slurry of the inorganic powder; (3) widening the pretreated carbon fiber to form a carbon fiber strip, and then carrying out electrophoretic deposition on the inorganic powders; (4) preparing a preform from the deposited carbon fibers; and (5) compounding a matrix in the preform.

The present invention provides a prepreg which is composed of at least a matrix resin and reinforcing fibers, and which is characterized in that: conductive parts are formed on one surface or both surfaces of a fiber layer that is formed of the reinforcing fibers; and the volume resistivity ρ (Ωcm) of the fiber layer in the thickness direction, the thickness t (cm) of the fiber layer and the average interval L (cm) between the conductive parts arranged on the prepreg surface satisfy formula (1).
t/ρ×1/L×100≥0.5  Formula (1):

Provided is a method of manufacturing a FRP product that is obtained by integrally curing a prepreg where fibers are arranged in a specific direction, such as a unidirectional prepreg, a cloth prepreg, or a tow prepreg and a chopped fiber prepreg, such as a sheet molding compound, in which disorder of fiber arrangement in a portion obtained by curing the prepreg is suppressed to obtain an expected strength.

A carbon fiber complex material for a carbon fiber reinforced plastic composite material includes a carbon fiber material formed from a continuous carbon fiber, and carbon nanowalls formed on a surface of the continuous carbon fiber.

Methods of making fiber reinforced composite articles are described. The methods may include treating fibers with a sizing composition that includes a polymerization compound, and introducing the treated fibers to a pre-polymerized composition. The combination of the treated fibers and pre-polymerized composition may then undergo a temperature adjustment to a polymerization temperature at which the pre-polymerized composition polymerizes into a plastic around the fibers to form the fiber-reinforced composite article. Techniques for introducing the treated fibers to the pre-polymerized composition may include pultrusion, filament winding, reactive injection molding (RIM), structural reactive injection molding (SRIM), resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM), long fiber injection (LFI), sheet molding compound (SMC) molding, bulk molding compound (BMC) molding, a spray-up application, and/or a hand lay-up application, among other techniques.

A prepreg includes: a resin composition or a semi-cured product thereof; and a fibrous base material, wherein the resin composition contains a polymer having a structural unit expressed by the formula (1) in a molecule, and a curing agent each at a predetermined content rate. A cured product of the resin composition has a Dk of 2.6 to 3.8, and the fibrous base material includes a glass cloth having a Dk of 4.7 or less and a Df of 0.0033 or less. A cured product of the prepreg has a Dk of 2.7 to 3.8, and a Df of 0.002 or less.

##STR00001##

In the formula (1), Z represents an arylene group, R.sub.1 to R.sub.3 each independently represents a hydrogen atom or an alkyl group, and R.sub.4 to R.sub.6 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

The present disclosure provides a polymer matrix composite, and a laminate, a prepreg and a printed circuit board using the same. The polymer matrix composite includes a polymeric resin and a non-woven inorganic material having a dielectric constant of from about 1.5 to about 4.8 and a dissipation factor at 10 GHz below 0.003. The printed circuit board uses the laminate including the polymer matrix as a core layer which is sandwiched between at least two outer layers.