Abstract: Provided is a nanofiber sheet that sufficiently refined by fibrillation and has high crystallinity of cellulose fiber and can realize a fiber-reinforced composite material exhibiting high transparency, a high elastic modulus, a low coefficient of linear thermal expansion, and high heat resistance and being high in flatness and smoothness. This nanofiber sheet includes crystalline cellulose as the main component and a lignin in an amount of from 10 ppm to 10 wt %. When a fiber/resin composite material obtained by impregnating the nanofiber sheet with tricyclodecane dimethacrylate, subjecting the impregnated product to UV-curing at 20 J/cm2, and heating the cured product in vacuum at 160° C. for two hours includes 60 wt % of the cured tricyclodecane dimethacrylate and 40 wt % of nanofiber, the following physical characteristics (i) to (iii) are satisfied: (i) the parallel light transmittance of light of a wavelength of 600 nm at a sheet thickness of 100 ?m is 70% or more; (ii) the Young's modulus is 5.

Abstract: The present invention relates to a fiber-reinforced composite material and a method for manufacturing the same, and also relates to a transparent multilayered sheet, a circuit board, and an optical waveguide.

Abstract: Disclosed is a highly transparent fiber-reinforced composite material including an assembly of cellulose fibers of 4 to 200 nm average fiber diameter impregnated with a matrix material so as to not only remedy the moisture absorbency attributed to cellulose fibers but also further improve transparency. There is provided a fiber-reinforced composite material including an assembly of cellulose fibers impregnated with a matrix material. In the fiber-reinforced composite material, hydroxyl groups of cellulose fibers are chemically modified through a reaction with one or more chemical modifiers selected from the group consisting of an acid, an alcohol, a halogenating reagent, an acid anhydride, and an isocyanate so that the ratio of a functional group introduced by the chemical modification is 5 to 40 percent by mole based on the hydroxyl groups of cellulose fibers before the chemical modification.

Abstract: There is provided a fiber-reinforced composite material containing fibers having an average fiber diameter of 4 to 200 nm and a matrix material, the composite material having a visible light transmittance of 60% or more at a wavelength of 400 to 700 nm, which is a conversion value based on a thickness of 50 ?m. A fiber-reinforced composite material composed of a matrix material and a fiber aggregate impregnated therewith is provided, in which when a segment length of a bright region corresponding to a pore region of the fiber aggregate is represented by L, which is obtained by statistical analysis of a unidirectional run-length image formed from a binary image obtained by binarization of a scanning electron microscopic image of the fiber aggregate, the total length of segments that satisfy L?4.5 ?m is 30% or less of the total analyzed length.

Abstract: There is provided a fiber-reinforced composite material containing fibers having an average fiber diameter of 4 to 200 nm and a matrix material, the composite material having a visible light transmittance of 60% or more at a wavelength of 400 to 700 nm, which is a conversion value based on a thickness of 50 ?m. A fiber-reinforced composite material composed of a matrix material and a fiber aggregate impregnated therewith is provided, in which when a segment length of a bright region corresponding to a pore region of the fiber aggregate is represented by L, which is obtained by statistical analysis of a unidirectional run-length image formed from a binary image obtained by binarization of a scanning electron microscopic image of the fiber aggregate, the total length of segments that satisfy L?4.5 ?m is 30% or less of the total analyzed length.