Hughes Aircraft Company

United States of America As Represented by the Secretary of the Air Force

Norman Bilow

Abraham L Landis

Leroy J Miller

William B Austin

Ralph D Hermansen

Preston S DuPont

Michael N Gardos

Preston S Du Pont

Boyce G Kimmel

A protective coating for solar cells, particularly solar cells positioned in space and which coating is a polyimide which is colorless, transparent, relatively non-brittle, has a high degree of thermal stability and readily transmits solar radiation without appreciable degradation. The coating is heat resistant and does not degrade significantly when exposed to ultraviolet radiation, and is highly effective in repelling low energy proton particles. In a preferred embodiment, the protective polymide coating is a polymer having the following recurring structural unit: ##STR1##

Polyimide composition and method for protecting photoreactive cells

A protective coating for solar cells, particularly solar cells positioned in space and which coating is a polyimide which is colorless, transparent, relatively non-brittle, has a high degree of thermal stability and readily transmits solar radiation without appreciable degradation. The coating is heat resistant and does not degrade significantly when exposed to ultraviolet radiation, and is highly effective in repelling low energy proton particles. In a preferred embodiment, the protective polyimide coating is a polymer having the following recurring structural unit: ##STR1##

A method of making an epoxy prepolymer curing agent is disclosed. The method comprises the steps of reacting a mixture of piperidine and an epoxy resin so as to form an epoxy prepolymer adduct. The adduct is mixed with 2-ethyl-4-methylimidazole thereby forming the curing agent composition.

Method of making an epoxy prepolymer curing agent

A high char yielding matrix resin for use in fabricating carbon-carbon composites comprised of a polymerizable mixture of a diethynylbenzene monomer and an ethynylpyrene monomer.

Diethynylbenzene-ethynylpyrene copolymers

Diethynylbenzene-ethylnylpyrene copolymers

Diethynyl substituted aromatic hydrocarbons are prepared which homopolymerize into resins suitable for use as high char materials.

Diethynyl aromatic hydrocarbons which homopolymerize and char

Improved diimide and polyimide oligomers containing phenylacetylene terminal groups have been produced which melt at low temperatures and are curable into useful laminating resins, molding compounds and matrix resins. These oligomers are analogous to diimides and polyimides made from conventional dianhydrides, such as benzophenonetetracarboxylic dianhydride or pyromellitic dianhydride.

Acetylene terminated imide oligomers which melt at low temperatures

The present invention is directed to a novel class of polynitrile (polycyano) substituted polyimide oligomers and the polyamic acid or ester precursors thereof. The nitrile groups on the oligomers allow the compounds to be cured through addition reactions which result in little or no outgassing. In addition, these oligomers are curable with heat in the presence of catalysts such as those which induce cyano trimerizations. The fully cured polyimides derived from these oligomers have excellent thermal and mechanical properties at high temperatures.

Nitrile substituted polyimide precursors

Novel thermosetting oligomers are formed by reacting epoxy prepolymers with aminoarylacetylenes. When heated to 170.degree. C. or above, these oligomers undergo acetylenic polymerization to form resins which exhibit superior thermal and hydrolytic stability when compared to conventionally cured epoxy resins.

Ethynyl-terminated epoxy resin derivatives and process for making the

Acetylene-substituted tetraimines are synthesized to form oligomers or prepolymers having melting points as low as 40.degree. C. and which can be polymerized into thermoset plastics at temperatures as low as 150.degree. C.

Homopolymerizable acetylene-terminated tetraimines and process for

Acetylene-substituted Schiff's bases are prepared by the reaction of either acetylene-substituted amines and dicarboxaldehydes or acetylene-substituted aldehydes and diamines. These compounds are polymerizable and in some examples they yield conjugated polymers useful in the fabrication of conductors and semiconductors.

Polymeric Schiff's bases containing acetylene terminal groups

Nitrile substituted polyimide oligomers

A dianhydride is converted into an alcohol-soluble di-ester and subsequently used to form a lacquer with a mixture of a diamine and an aminoarylacetylene. When the solvent is removed and the mixture of compounds is heated to a curing temperature a cured acetylene-end-capped polyimide polymer is produced.

Process for synthesizing acetylene-substituted polyimides and polyimides

A new class of copolymers obtained via the copolymerization of diethynylbenzene with an ethynyl-substituted polyimide oligomer has been used to prepare composite materials exhibiting zero void content. The copolymers are thermosetting in character and are particularly useful for the fabrication of composite structures such as glass fiber reinforced laminates and molding compounds and graphite fiber reinforced laminates and molding compounds.

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Encino, CA, United States of America

Norman Bilow