Abstract: Methods, apparatus, and systems for impregnation of fibers and their use in the fabrication of composite structures using two or more different but cooperative matrix components applied to separate tows of dry fibers to form single component prepregs. A single tow of dry fibers may also be impregnated with one matrix component and subsequently with at least one other matrix component. The first matrix component may predominantly comprise a substantially uncatalyzed component and the at least one other matrix component may predominantly comprise a substantially unreacted hardener component. Until the at least two components are combined, the tows impregnated with the at least two different matrix components have virtually infinite shelf life at room temperature. Only when at least two differently impregnated tows are combined during the composite fabrication process is an overall stoichiometrically correct matrix composition obtained to enable the final curing and hardening of the composite part.

Abstract: Fiber laminations with a resin therein are advanced to substantial cure in situ while resin-impregnated fiber (in the form of individual tows, a band thereof, or a tape) is being placed on a workpiece on the mandrel by preheating the fiber in a temperature range of 100-700° F. for partially advancing the cure of the resin in the fiber, shaping the fiber to the desired shape, and laying up the partially advanced fiber on the workpiece on the mandrel while simultaneously nip-point heating the fiber in an area proximate to the point where the fiber is being placed on the workpiece. A plurality of parameters are monitored during this placement in order to control the nip-point heating so that the resin in the fiber is substantially cured while the fiber is being placed on the workpiece.

Abstract: A resin composition especially suited to the resin transfer molding and wet filament winding processes is composed of epoxide compounds and one or more aromatic amine hardeners wherein the blend of epoxide compounds is (i) a diglycidyl ether of the reaction product of a bisphenol and a blend of (a) a diglycidyl ether of bisphenol A other than that of (i) and (b) a halohydrin having about two epoxy groups per molecule, (ii) a copolymer of ethyl hexyl acrylate and glycidyl methacrylate and (iii) a neopentyl glycol digylcidyl ether. This composition has a low viscosity, and when cured, exhibits high toughness and mechanical strengths useful in making high performance composites.