Phthalonitrile Prepolymer as High Temperature Sizing Material for Composite Fibers.
Patent Application, Filed 28 Jun 93,
DEPARTMENT OF THE NAVY WASHINGTON DC
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Sized fibers, for use as reinforcements in high temperature polymeric composites, are prepared by coating the outside surface of the fibers with an amorphous, B-stage bisphthalonitrile prepolymer. The prepolymer may be prepared by curing a bisphthalonitrile monomer with an organic amine, an aromatic organic acid, a mineral acid, a Lewis acid or a salt of any of the above. Then, the fibers are coated by passage through an organic solution of the prepolymer. Either before or after completely curing the prepolymer coating on the fibers, the coated fibers are covered with a resin, for example, by passage through a solution or melt of a polyimide or bisphthalonitrile resin. If the phthalonitrile coating was incompletely cured prior to covering the phthalonitrile-coated fiber with the resin, the heat during the subsequent cure of the resin also completely cures the phthalonitrile coating. The resulting composite has excellent high temperature properties. In a preferred embodiment, the coated fibers are used to form a prepreg for usage in composite fabrication.
- Laminates and Composite Materials
- Manufacturing and Industrial Engineering and Control of Production Systems