In an epoxy resin composition, per 100 parts by mass of an epoxy resin component containing from 60 to 85 parts by mass of N,N,N′,N′-tetraglycidyldiaminodiphenylmethane resin (A) having a viscosity at 50° C. of 6000 mPa.Math.s or less and from 15 to 40 parts by mass of a liquid bisphenol A epoxy resin (B) having a viscosity at 25° C. of 20000 mPa.Math.s or less, from 8 to 15 parts by mass of a thermoplastic resin (C), from 2 to 10 parts by mass of elastomer microparticles (D) having an average particle diameter of 1000 nm or less, and from 0.5 to 2.5 parts by mass of silica microparticles (E) having an average particle diameter of 1000 nm or less are blended.

An aspect of the present invention is a resin composition containing a polybutadiene compound having an epoxy group in a molecule, a polyphenylene ether compound having at least one of a group represented by the following Formula (1) and a group represented by the following Formula (2) in a molecule, a styrene-based block copolymer, and a curing agent.

##STR00001##

In Formula (1), p represents 0 to 10, Z represents an arylene group, and R.sub.1 to R.sub.3 each independently represent a hydrogen atom or an alkyl group.

##STR00002##

In Formula (2), R.sub.4 represents a hydrogen atom or an alkyl group.

A graded-index optical element may include a nanovoided material including a first surface and a second surface opposite the first surface. The nanovoided material may be transparent between the first surface and the second surface. Additionally, the nanovoided material may have a predefined change in effective refractive index in at least one axis due to a change in at least one of nanovoid size or nanovoid distribution along the at least one axis. Various other elements, devices, systems, materials, and methods are also disclosed.

A curable benzoxazine resin composition for a fiber-reinforced composite material is provided which contains at least a component [A], a component [B], and a component [C]. The component [A] includes at least one multifunctional benzoxazine resin having a non-hydrocarbon linkage such as carbonyl, oxygen, sulfur, sulfone or sulfoxide between aromatic moieties. The component [B] includes at least one multifunctional benzoxazine resin having a direct bond or a hydrocarbon linkage between aromatic moieties. The component [C] includes at least one cycloaliphatic epoxy resin containing at least two epoxy groups which are part of cycloaliphatic rings. The curable benzoxazine resin composition is useful in the molding of fiber-reinforced composite materials. More particularly, the curable benzoxazine resin composition makes possible a fiber-reinforced composite material where the cured material obtained by heating has superior performance in extreme use environments, such as high temperature and high compressive load.

The present invention relates to a method for producing a composite structure comprising a magnetic filler material embedded in a resin matrix. So far, a balance between sufficient magnetic performance and mechanical fatigue resistance, for applications involving cyclic strains of hundreds of thousands of cycles, has not been achieved, largely due to the poor compatibility between metallic and plastic surfaces. The present invention solves this problem by embedding magnetic filler material in a resin, after the magnetic filler material has been subjected to a possible surface treatment for improving the adhesion of the magnetic filler material to the resin matrix in the composite structure. Further, a composite structure comprising magnetic filler material embedded in a resin matrix obtainable by the method as disclosed in the current specification is disclosed. Still further, the use of the composite structure in applications requiring magnetic properties and resistance to mechanical fatigue is disclosed.

A color-changing polymeric material is provided. The material is formed from a thermoplastic composition containing a continuous phase that includes a matrix polymer, colorant, microinclusion additive, and nanoinclusion additive, wherein the microinclusion additive and nanoinclusion additive are dispersed within the continuous phase in the form of discrete domains. A porous network is formed in the polymeric material when subjected to a deformational strain in a solid state. The polymeric material exhibits a first color prior to being subjected to the deformational strain and a second color after being subjected to the deformational strain, the first color being different than the second color.

A prepreg may include: a reinforcing fiber material including carbon fibers; and a resin composition with which the reinforcing fiber material is impregnated. The resin composition may include an epoxy resin (A), an amine curing agent (B), and an imidazole curing agent (C). The amine curing agent (B) may be present in a range of from 1 to 3.8 parts by mass, relative to 100 parts by mass of the epoxy resin (A). The amine curing agent (B) and the imidazole curing agent (C) may be present in a total amount of not more than 10 parts by mass, relative to 100 parts by mass of the epoxy resin (A). The imidazole curing agent may include an imidazole compound including, in its molecular structure, a triazine ring.

An epoxide resin for the manufacture of a fibre-reinforced composite material having fire retardant properties and/or for use as an adhesive or hot-melt adhesive having fire retardant properties, the epoxide resin being halogen-free and phenolic resin-free, the epoxide resin comprising: A. a mixture of (i) at least one first non-halogenated multifunctional epoxide-containing resin which has an epoxide functionality of greater than 2 and (ii) at least one second non-halogenated multifunctional epoxide-containing resin which has an epoxide functionality of less than or equal to 2; B. at least one catalyst for curing the mixture of epoxide-containing resins to form a cured epoxy resin; and C. at least one fire retardant additive for forming an intumescent char when the cured epoxy resin is exposed to a fire, wherein the at least one fire retardant additive comprises expandable flake graphite and wherein the expandable flake graphite is present in a concentration of from 0.09 to 2.5 wt % based on the weight of the epoxide resin.

A nanovoided polymer-based material may include a bulk polymer material defining a plurality of nanovoids and an interfacial film disposed at an interface between each of the plurality of nanovoids and the bulk polymer material. The interfacial film may include one or more layers of material. A method of forming a nanovoided polymer-based material may include (1) forming a bulk polymer material defining a plurality of nanovoids and (2) forming an interfacial film at an interface between each of the plurality of nanovoids and the bulk polymer material. Various other methods, systems, and materials are also disclosed.

A reinforcing fiber mat includes reinforcing fiber bundles having an average fiber length of 5 mm to 100 mm, wherein reinforcing fiber bundles consisting of 86 or more fibers per bundle are contained at a weight content of more than 99 wt % to 100 wt % and the reinforcing fiber bundles contain single yarns by 500 fibers/mm-width or more and 1,600 fibers/mm-width or less and have a drape level of 120 mm or more and 240 mm or less.