Abstract: A prepreg containing the following constituent elements [A] to [C], wherein a resin composition containing the constituent elements [B] and [C] has a higher-order structure derived from a diffraction angle 2? between 1.0° and 6.0° observed with X-ray diffraction after curing: [A]: carbon fibers [B]: epoxy resin [C]: curing agent of [B].

Abstract: A prepreg, which includes a carbon fiber reinforced material, has excellent Mode I interlaminar toughness, Mode II interlaminar toughness, and tensile strength. The prepreg includes the following constituents [A] to [C] and satisfies the following conditions (I) and (II): [A]: a carbon fiber; [B]: an epoxy resin; and [C]: a hardener for [B], and (I) a surface oxygen concentration O/C of [A] measured by X-ray photoelectron spectroscopy is 0.10 or more; and (II) a cured product obtained by curing [B] and [C] includes a resin region having molecular anisotropy exhibiting interference fringes in polarizing microscope observation in a crossed Nicol state.

Abstract: The invention provides a prepreg having high storage stability and serving suitably for producing components, such as structural members and interior members of aircraft and structural members of aircraft engines, that require high heat resistance under high temperature and high humidity conditions, where the prepreg exhibits good physical properties and good combustion properties. The prepreg is produced by impregnating component [A] with an epoxy resin composition containing components [B] to [D], wherein component [A] in the prepreg accounts for 50 mass % or more, where [A] is a carbon fiber, [B] is an epoxy resin, [C] is a fluorene type curing agent having a maximum particle size of 100 ?m or less, and [D] is a thermoplastic resin.

Abstract: Provided is a prepreg including the following constituents [A] to [C], the prepreg satisfying the following conditions [I] to [III]: [A]: a sizing agent-coated carbon fiber; [B]: an epoxy resin having a specific structure; and [C]: a hardener for [B], [I]: an epoxy resin composition including the constituents [B] and [C] has a nematic-isotropic phase transition temperature in a temperature range of 130° C. to 180° C.; [II] a prepreg after isothermal holding at 100° C. for 30 minutes does not have a high-order structure originated from a diffraction angle of 2?=1.0° to 6.0° measured by wide angle X-ray diffraction at 100° C.; and [III]: a prepreg after isothermal holding at 180° C. for 2 hours has a high-order structure originated from the diffraction angle of 2?=1.0° to 6.0° measured by wide angle X-ray diffraction at 180° C.

Abstract: A prepreg includes following constituents [A] to [C] and satisfies following conditions (I) and (II): [A]: a carbon fiber; [B]: an epoxy resin; and [C]: a hardener for [B], and (I) a surface oxygen concentration O/C of [A] measured by X-ray photoelectron spectroscopy is 0.10 or more; and (II) a cured product obtained by curing [B] and [C] includes a resin region having molecular anisotropy exhibiting interference fringes in polarizing microscope observation in a crossed Nicol state.

Abstract: A prepreg containing the following constituent elements [A] to [C], wherein a resin composition containing the constituent elements [B] and [C] has a higher-order structure derived from a diffraction angle 20 between 1.0° and 6.0° observed with X-ray diffraction after curing: [A]: carbon fibers [B]: epoxy resin [C]: curing agent of [B].