General Electric Company

Raytheon Company

Maverick Corporation

Robert A Gray

Philip C Sturman, Jr

Frank Wayne Harris

Dong Zhang

Gray E Fowler

Emerald James Adair

Michael M Liggett

Richard N Griffin

Michael M Liggeit

The disclosed compositions and methods for producing composite materials that are suitably adapted for use in elevated temperature environments generally include the use of oxyarylbisorthodinitrile matrix resins in conjunction with aromatic amines to produce an improved phthalonitrile-based composite. Various features and specifications may be controlled, adapted or otherwise optionally modified to improve the temperature-rated performance of the disclosed composite materials. Exemplary embodiments of the present invention generally provide composite materials that offer improved strength at temperatures in excess of 600&#xb0; F.

Phthalonitrile composites

The present invention is directed to polyimide systems which simultaneously offer low toxicity, a high glass transition temperature, excellent thermal oxidative stability, and desirable processing characteristics. These various polyimide systems include mixtures of monomeric reactants, polyimide-precursor reaction products, polyimides, and polyimide-containing articles. In one aspect of the invention, the mixture of monomeric reactants includes at least one dia-nhydride or a derivative thereof, and at least one diamine. The diamine may be 4,4&prime;-&lsqb;1,4-phenylene-bis(1-methylethylidene)&rsqb;bisaniline, 4,4&prime;-&lsqb;1,3-phenylene-bis(1-methylethylidene)&rsqb;bisaniline, and/or a derivative thereof. The diamine also may include a phenylenediamine, 2,2-bis&lsqb;4-(4-aminophenoxyl)phenyl&rsqb;propane, 4,4&prime;(1,4-phenylene-bismethylene)bisaniline, and/or a derivative thereof. In addition, the mixture may include a reactive end-capping agent and/or a non-reactive end-capping agent. Also, if desired, the mixture of monomeric reactants may be a dry mix or a solution. The invention also is directed to articles formed from mixtures of monomeric reactants, articles formed from polyimide-precursor reaction products, and articles formed from polyimides themselves. Non-limiting examples include a powder, a neat resin, a coating, a film, a membrane, a foam, an adhesive, a fiber, a composite, a laminate, a prepreg, a part, and a bushing.

Low-toxicity, high-temperature polyimides

Induction heating is utilized to heat polymer matrix composites containing electrically conductive fibers. This is accomplished with an apparatus having a mold with first and second cores positioned to receive a workpiece therebetween and first and second induction coils mounted to the first and second cores, respectively. Each induction coil is encapsulated in a layer of non-electrically conductive material which is attached to a surface of the respective core. A thermal insulation layer is attached to each layer of material, and a skin layer is attached to each thermal insulation layer. Alternatively, the induction coils can be embedded in the corresponding mold core. In another alternative, a single helical induction coil can be disposed around the two mold cores.

Induction heating of polymer matrix composites in a mold press

Induction heating is utilized to heat polymer matrix composites containing electrically conductive fibers. This is accomplished with an apparatus having a mandrel for supporting a composite workpiece and a helical induction coil disposed around the mandrel. The mandrel, workpiece and induction coil are disposed in an autoclave. The mandrel is a hollow, porous member having a port formed therein which is connected to a vacuum. A vacuum bag is hermetically sealed on the mandrel so as to define an enclosure over the workpiece. A power source is connected to the induction coil and, when activated, causes the coil to generate an oscillating magnetic field lying along the longitudinal axis of the mandrel. The magnetic field induces heat-generating eddy currents in the fibers of the workpiece which are oriented orthogonally to the magnetic field.

Induction heating of polymer matrix composites in an autoclave

Polyimide intercondensation products are prepared from mixed dianhydrides and aromatic diamines. One of the mixed dianhydrides must be 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA) and the other dianhydride may be oxydiphthalic anhydride (ODPA) or biphenyl dianhydride (BPDA) or mixtures thereof. Preferred aromatic diamines are p-phenylenediamine (PPD) and/or m-phenylenediamine (MPD). The polyimide products have increased glass transition temperatures (Tg), frequently higher than 400.degree. C. Composites made from the polyimides have high thermal and oxidative stability and may be used in aircraft engine hardware.

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Cincinnati, OH, United States of America

Robert A Gray