Methods for recycling thermoset polymers, particularly by changing them into dynamic networks with the use of an appropriate catalyst solution which transforms the thermoset polymer into a vitrimer-like composition. The methods include the step of swelling a crosslinked thermoset polymer in a solution including a catalyst, whereby the catalyst diffuses into the thermoset polymer, in particular into the thermoset network. Upon removal of the liquid portion of the solution, such as solvent, the catalyst facilitates the occurrence of exchange reactions at elevated temperatures, rendering the system a dynamic network. The vitrimerized composition having the thermoset polymer and catalyst is recyclable and processable and thus suitable for many end uses.

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.

The present invention addresses the problem of providing a prepreg that has excellent short-time and low-pressure handling properties, during pasting and layering work. In order to solve the problem, this invention has the following configuration. The prepreg includes reinforcing fibers and an epoxy resin composition, has a fiber content of 90 mass % or less, and satisfies conditions (a) and (b) below. (a) When the average thickness of the prepreg is set as D (D being 3 m or greater), the viscosity at 25 C. of the epoxy resin composition at a site (I) located at a depth of D/4 to 3D/4 from the surface on one side of the prepreg is 50,000 to 300,000 Pa.Math.s inclusive. (b) From among sites (II) located at a depth of up to 0.5 m from each surface on both sides of the prepreg, the viscosity at 25 C. of the epoxy resin composition at least at a site (II) on the one side is 10,000 to 40,000 Pa.Math.s inclusive.

A prepreg including: a component (A); a component (B); and a component (C), in which the component (A) is a reinforced fiber substrate, the component (B) is an epoxy resin composition, the component (C) is a component (c1) or a component (c2), the component (c1) includes polyamide particles and thermosetting polyimide particles, and the component (c2) includes spherical polyamide particles having a melting point of 140 C. to 175 C.

Composite honeycomb that may be contoured to form composite honeycomb structures, which have tight radii of curvatures and/or compound curvatures, and which are suitable for use in high temperature environments. The method for making the composite honeycomb involves using high temperature prepreg to make a flexible composite honeycomb that is formed into a composite honeycomb precursor. A high temperature coating resin is applied to the composite honeycomb precursor to form the high temperature composite honeycomb.

An object of the present invention is to provide a molding material which can suppress film lifting, gives good peelability of release paper, and can produce therefrom a fiber-reinforced composite article with good demoldability from a metal mold, and a fiber-reinforced composite article. The molding material of the present invention comprises an epoxy resin composition comprising a component (A): an epoxy resin, a component (B): an epoxy resin curing agent, and a component (C): an unsaturated fatty acid ester compound having a melting point or pour point of 25 C. or lower; and a reinforcing fiber substrate, wherein the reinforcing fiber substrate is impregnated with the epoxy resin composition.

The present disclosure relates to epoxide containing compounds comprising three benzene units linked by bridging groups. The disclosure also relates to the production of curable epoxy resin formulations comprising said epoxide containing compounds, and their possible incorporation into composite materials such as fibre reinforced composites. Possible methods for formulating the compounds epoxide containing compounds, as described herein, are also disclosed.

A tape prepreg formed by impregnating, with resin, a reinforcing fiber bundle in which reinforcing fibers are aligned in one direction, in which a cross-section of the tape prepreg bundle perpendicular to an orientation direction has a portion in which a thickness continuously increases from one end portion and the other end portion in a width direction toward the center in the width direction, and all angles formed by any one boundary line in a thickness direction of the perpendicular cross-section and a boundary line in the width direction are acute angles.

Composite honeycomb that may be contoured to form composite honeycomb structures, which have tight radii of curvatures and/or compound curvatures, and which are suitable for use in high temperature environments. The method for making the composite honeycomb involves using high temperature prepreg to make a flexible composite honeycomb that is formed into a composite honeycomb precursor. A high temperature coating resin is applied to the composite honeycomb precursor to form the high temperature composite honeycomb.

The present invention provides a SMC of which excessive thickening with time is suppressed while of which sufficient initial thickening by an isocyanate-based thickener is maintained, particularly of which a decrease in flowability at the time of molding to be easily actualized in the case of containing an aromatic vinyl compound such as styrene is suppressed, and which exhibits excellent storage stability and moldability, a molding material for obtaining the SMC, and a fiber-reinforced composite material using the SMC. The invention provides a molding material including: a matrix resin composition containing the following Component (A), the following Component (B), the following Component (D) and the following Component (E); and the following Component (C), in which a proportion of the Component (E) with respect to 100 parts by mass of a sum of the Component (A) and the Component (B) is 0.002 part by mass or more and 0.08 part by mass or less: Component (A): a compound having either or both of a hydroxyl group and a carboxyl group and a polymerizable unsaturated group, Component (B): an aromatic vinyl compound, Component (C): a reinforcing fiber bundle having a fiber length of 5 mm or more and 120 mm or less, Component (D): an isocyanate compound, and Component (E): a metal chelate compound.