Abstract: The invention relates to the production of composite materials having a fibrous reinforcement and matrix obtained by the polymerization of acrylic monomers.These acrylic monomers are tetraacrylates of formula: ##STR1## in which R.sup.1 and R.sup.2, which can be the same or different, represent H or CH.sub.3, and Z is a divalent group having 1 or 2 aromatic or aliphatic cycles.For example, Z is a group derived from bisphenol A and R.sup.1 and R.sup.2 represent H.The composite materials can be prepared by injection moulding.

Abstract: Process for the preparation of a polysilane crosslinked by ioning radiation and process for the production of a composite material having a polysilane matrix. The preparation process consists of subjecting to ionizing radiation chosen from among X-rays and an electron bombardment, a formulation crosslinkable by ionizing radiation incorporating at least one polysilane having at least one vinyl termination.

Abstract: Prepolymers having imide groupings and process for their preparation, for use in the production of resins capable of hardening under ionizing radiation. The prepolymers are derived from the reaction in a homogeneous liquid medium, at a temperature of between 50.degree. and 250.degree. C. of, firstly, imide grouping-generating reagents consisting of a least two specific maleimides of different kinds, and, secondly, two additional reagents, composed of a specific acrylate reagent and a specific vinyl compound other that an acrylate.

Abstract: According to the invention, the reactive lubricating product of carbon fibres for embedding in a resin which can be hardened by X or beta radiation according to a radical mechanism is constituted by a monomer having at least one functional group (F.sub.1) able to form a covalent chemical bond with the hydroxyl sites of the carbon fibres and an ethylene unsaturation (F.sub.2) able to crosslink with the resin during its hardening under irradiation.

Abstract: A part made of a resin-containing composite material, also having at least one insert made of a different material, is hardened by electron beam radiation in zones having a surface mass at the most equal to 4 g/cm.sup.2 and by X-radiation in zones having a surface mass above 4 g/cm.sup.2. The X-radiation, in doses up to 10 Mrad, is produced by action of the electron beam on a target placed between the part and the electron beam.

Abstract: Apparatus for the polymerization and/or crosslinking of a resin used in the composition of a composite material part having a variable thickness by means of ionizing radiation.The apparatus comprises means for producing an electron beam, means for directing the electron beam onto a target, which is able to produce under the action of the electron beam X-radiation offering adequate doses for crosslinking the resin, as well as means for carrying out a relative movement between the ionizing radiation and the part, so that the latter is wholly or partly exposed to the action of said radiation. It makes it possible to polymerize a part by X or electron beams, as a function of the thickness requirements thereof.