Method of increasing the strength and fatigue resistance of fiber reinforced composites

This application relates to a means of increasing the amount of entrained vapor in fiber-reinforced composite materials. Specifically, the present invention relates to a method of increasing the amount of entrained vapor in composite products formed during filament winding operations, these products having high resistance to cyclic fatigue and excellent strength retention. The invention accomplishes these effects by incorporating a chemical foaming or blowing agent into the resin matrix composition used to form the composites. When the resin matrix composition is cured, vapor-filled voids are formed which improve the strength and resistance of the composite products. Also described are composite materials containing such resin compositions, and articles made from the composites. A method of increasing the amount of entrained vapor in fiber-reinforced resin composite materials, and in particular filament wound composites, wherein a particularly effective chemical foaming or blowing agent is incorporated into the resin matrix composition used to form the composites. The foaming agent creates vapor-filled voids throughout the resin matrix of the composite as it cures. The superior composites containing these vapor-filled voids demonstrate high burst strength retention and excellent resistance to cyclic fatigue. The invention also relates to composite materials and articles thereof.