Fire Resistant Composites

Use of graphite/resin composites in engine nacelles has been restricted because the resin is flammable. Fiberglass/polyimide and graphite/polyimide laminates were treated with various phosphorylated polymers to obtain enhanced fire-resistance and high-char-yield products after exposure to a 2000°F flame for 15 minutes. Tensile, flexural shear, and interlaminar shear strengths were determined. Polymeric phosphorylated hydrazides were found to give the best fire-resistance.