The present invention pertains to a prepreg containing reinforcing fibers and an epoxy resin composition. Said prepreg is sandwiched between dies preheated to 140.degree.C. and pressurized to MPa and held for five minutes at this temperature to obtain a cured article having a GTg of at least 150.degree.C. The present invention also pertains to a fiber-reinforced composite material and a method for producing same. According to this invention, it is possible to provide a prepreg which is well suited to press-molding, particularly to high-cycle press-molding. It is also possible to provide a fiber-reinforced composite material which can be heat-cured at a lower temperature and over a shorter time than conventional methods, with which it is possible to minimize excessive flow of resin in hot-press curing, and which is resistant to performance defects such as fiber meandering and defects in surface appearance. A method for producing the same can also be provided.

A process of forming a lactide copolymer includes forming a dimethylidene lactide molecule from an L-lactide molecule. The process also includes forming a functionalized lactide monomer from the dimethylidene lactide molecule. The process includes forming a mixture that includes the functionalized lactide monomer and a bisphenol A (BPA) monomer or a BPA-derived monomer. The process further includes polymerizing the mixture to form a lactide copolymer.

An in-situ polymerized type thermoplastic prepreg is provided, which is excellent in productivity, has tack properties and drape properties that allow easy shaping in a mold, is excellent in handling properties, and allows a molded product obtained by curing to have both mechanical properties as high as those of a thermosetting composite and the features of the thermoplastic composite. An in-situ polymerized type thermoplastic prepreg 1 includes reinforcing fibers 2 and an in-situ polymerized type thermoplastic epoxy resin 3 as a matrix resin. The in-situ polymerized type thermoplastic epoxy resin 3 is cured to B-stage, with the weight-average molecular weight being 6,000 or less, and has tack properties and drape properties at 30 C. or less, and the in-situ polymerized type thermoplastic epoxy resin after curing has a weight-average molecular weight of 30,000 or more.

This epoxy resin composition contains an epoxy resin (A) having at least three glycidyl groups in the molecule, an epoxy resin (B) having at least one sulfur atom in the molecule, and an imidazole compound (C) containing at least one of 2-phenyl-4,5-dihydroxymethyl imidazole and 2-phenyl-4-methyl-5-hydroxymethyl imidazole.

The present teachings contemplate relatively high glass transition temperature (T.sub.g) polymers and/or other reaction products. A method may include reacting a diepoxide with a bisphenol in amounts and under conditions to produce a material that has a T.sub.g as measured by differential scanning calorimetry according to ASTM E1358-08(2014) of at least about 90 C. at [east about 100 C. (at least about 110 C., or at least about 120 C.

The present invention provides a compound represented by the general formula (I), and a polymerizable composition containing the compound. When the polymerizable composition containing the compound represented by the formula (I) is used to form a filmy product, the resulting filmy product exhibits less change over time in phase difference and reverse wavelength dispersion and when the filmy polymer is irradiated with UV light, peeling from a substrate is unlikely to be caused. Further, the invention provides a polymer obtained through polymerization of the polymerizable composition and an optically anisotropic body obtained using the polymer.

An epoxy resin composition produces a cured product having improved elastic modulus and improved nominal strain at compressive fracture. The epoxy resin composition is a fiber-reinforced composite material having excellent compression strength and interlayer toughness. The epoxy resin composition contains at least the following constituent components [A], [B] and [C]. [A] A specific ortho type epoxy resin. [B] At least one component selected from the group consisting of: thermoplastic resins that are compatible with the epoxy resin [A]; and core-shell type polymers. [C] An amine curing agent.

A process of forming a lactide copolymer includes forming a dimethylidene lactide molecule from an L-lactide molecule. The process also includes forming a functionalized lactide monomer from the dimethylidene lactide molecule. The process includes forming a mixture that includes the functionalized lactide monomer and a bisphenol A (BPA) monomer or a BPA-derived monomer. The process further includes polymerizing the mixture to form a lactide copolymer.

An object of the present invention is to provide a crosslinkable composition as a new crosslinking precursor, comprising a multifunctional epoxy compound using a plant component as a raw material, and a cured product obtained by curing the crosslinkable composition. The present invention provides a crosslinkable composition comprising: a plant-based multifunctional epoxy compound; and a crosslinking agent, wherein the multifunctional epoxy compound is obtained by multifunctionalizing limonene oxide, and the crosslinking agent is a polyalkyleneimine.

The present invention is an epoxy resin composition characterized by containing component A (epoxy resin containing sulfur atoms in the molecule thereof); and component B (an epoxy resin composition containing an imidazole compound represented by formula (1), and at least one of the following components: component C (an imidazole compound represented by formula (2) below) or component D (an epoxy resin composition having at least one sulfur atom in the molecule. According to the present invention, it is possible to provide an epoxy resin composition which has outstanding stability when stored at room temperature, and which can be heat-cured at a relatively low temperature and over a short time, to give a resin with a high heat resistance when cured. (In formula (1), R.sup.1 represents a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, R.sup.2 represents a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, or a hydrogen atom.) (In formula (2), R.sup.3 represents an organic group having 1 or more carbon atoms, and R.sup.4 to R.sup.6 represent hydrogen atoms, methyl groups or ethyl groups.) ##STR00001##