Trw Limited

Northrop Grumman Systems Corporation

Michael K O'Rell

Robert J Jones

Christian Harris

James Wehner

Robert W Vaughan

Jim M Hom

Clyde H Sheppard

Howard E Green

Robert A Buyny

James D Sutherland

A spacecraft including control vanes for controlling the pointing direction of the spacecraft by providing a variable absorptive, reflective, emissive and/or transmissive properties. The control vanes provide a torque on the spacecraft to maintain the spacecraft pointing towards the sun. The control vanes can include at least one x-axis control vane and at least one y-axis control vane where the xaxis control vane provides x-axis control torque on the spacecraft rotated about the x-axis, and the y-axis control vane provides y-axis control torque on the spacecraft when rotated about the y-axis.

Spacecraft including control vanes having variable absorptive, reflective and emissive characteristics

Controlling the solar torque imposed on a spacecraft () in flight by providing a film () with variable absorptive, reflective, emissive and/or transmissive properties on the sun side of a thermal shield () of the spacecraft (). As the orientation of the thermal shield () changes relative to the sun line, the absorptive, reflective, emissive and/or transmissive properties of the shield () change to cause the shield's () center of solar pressure to change, thus aligning it with the spacecraft () center of mass () as viewed from the direction of the sun line. In accordance with another embodiment of the invention, the spacecraft () is provided with a plurality of control vanes (110&#x2013;116) that have a variable absorptive, transmissive, reflective and emissive property to maintain the spacecraft () stably pointed towards the sun.

Method for aligning a spacecraft

Controlling the solar torque imposed on a spacecraft () in flight by providing a film () with variable absorptive, reflective, emissive and/or transmissive properties on the sun side of a thermal shield () of the spacecraft (). As the orientation of the thermal shield () changes relative to the sun line, the absorptive, reflective, emissive and/or transmissive properties of the shield () change to cause the shield's () center of solar pressure to change, thus aligning it with the spacecraft () center of mass () as viewed from the direction of the sun line. In accordance with another embodiment of the invention, the spacecraft () is provided with a plurality of control vanes () that have a variable absorptive, transmissive, reflective and emissive property to maintain the spacecraft () stably pointed towards the sun.

Solar torque control using thin film directionally reflective, emissive, absorptive and transmissive surfaces

Vinyl polybutadiene maleimide prepolymers which are peroxide curable are provided. The prepolymers are formed from the reaction product of a vinyl polybutadiene providing pendant vinyl groups and a maleimide and, more particularly, a mixture of aliphatic maleimides with cycloaliphatic or aromatic maleimides in combination with a peroxide-free radical initiator. The prepolymer is a vinyl polybutadiene backbone structure having grafted maleimide polymers forming cross-linking between polybutadiene backbone segments. The resultant prepolymer can be subsequently cured to a hard resin by heating in the presence of a peroxide-free radical initiator to form cross-linking between vinyl polybutadiene structures through the pendant vinyl groups. The resultant hard resin provides strength retention at elevated temperatures and exhibits a flexibility and strength without being brittle.

Flexibilized vinyl polybutadiene maleimide resins

Vinyl polybutadiene bisimide copolymers which are peroxide curable are provided by two methods of formation. In the first method a bisimide cross-linked vinyl polybutadiene prepolymer is formed by combining a high vinyl content polybutadiene providing pendant vinyl groups with a bisimide in the presence of a first free radical initiating catalyst. The resultant cross-linked prepolymer is cured to a hard resin by the formation of additional cross-linkages through the pendant vinyl groups by heating the prepolymer to a temperature of at least about 300.degree. F. in the presence of a second free radical initiating catalyst. The second method discloses a method wherein the bisimide cross-linkages are formed in situ. In the second method, a high vinyl content polybutadiene providing pendant vinyl groups is reacted with maleic anhydride to form a maleic anhydride vinyl polybutadiene adduct. The adduct is subsequently combined with an aromatic polyamine and a free radical initiating catalyst. The mixture is heated to about 250.degree. F. to form a prepolymer having bisimide cross-linkages between the vinyl polybutadiene backbone segments. By continuing to heat the prepolymer to at least about 300.degree. F. still in the presence of the free radical initiating catalyst, the prepolymer is cured to a hard resin by the formation of cross-linkages between the pendant vinyl groups.

Vinyl polybutadiene bisimide copolymers

This invention relates to a novel aromatic diamine and more particularly to the use of said diamine for the preparation of thermally stable high-molecular weight polymers including, for example, polyamides, polyamideimides, polyimides, and the like. This diamine is obtained by reacting a stoichometric amount of a disodium salt of 2,2-bis(4-hydroxyphenyl) hexafluoropropane with 4-chloronitrobenzene to obtain an intermediate, 2,2-bis[4-(4-nitrophenoxy)phenyl] hexafluoropropane, which is reduced to the corresponding 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane.

Fluorinated aromatic diamine

This invention relates to a novel aromatic dianhydride and more particularly to the use of said dianhydride for the preparation of thermally stable high-molecular weight polymers including, for example, polybenzimidazoles, polypyrrones, polyimides, and the like. This dianhydride is obtained by reacting a stoichiometric amount of a disodium salt of 2,2-bis(4-hydroxyphenyl) hexafluoropropane with 4-chloro-N-phenylphthalimide to obtain an intermediate, 2,2-bis[4-(3,4-phenylphthalimidephenoxy)phenyl] hexafluoropropane, which is oxidized to the corresponding bis[4-(3,4-dicarboxyphenoxy)phenyl]perfluoroisopropylidene dianhydride.

Perfluoroisopropylidene dianhydride and polyimides prepared therefrom

End-capping an aromatic diamine or a precursor formed by reaction of an aromatic diamine with an aromatic dianhydride with difluoromaleic anhydride yields prepolymers which thermally cure at temperatures from about 150.degree. to about 200.degree. C. to form polymers which display long-term thermal stability at temperatures up to 300.degree. C. and more.

Bis (difluoromaleimide) capped propolymers and polymers

Polyaminobismaleimides having superior thermomechanical properties can be produced by reacting maleimide terminated polyaliphatic ethers and maleimide terminated aromatic compounds with an aromatic diamine. These bismaleimide polymers display high recoverable elongation together with good tensile adhesive and electrical properties and thermal and fuel stability.

Compliant maleimide based plastics

Polyimides prepared from perfluoroisopropylidene diamine

A monomeric bis (benzil) composition is produced by reacting furfural with an aromatic dialdehyde, the product having the structure: ##STR1## wherein R is a difunctional aromatic radical, R' is a hydrogen, a phenylene, or a furan radical, and R' is a hydrogen or or an alkyl substituent. These monomers are used to prepare cross-linked polyquinoxaline resins which have enhanced thermal and mechanical properties. Polymerization of these bis(benzil) monomers occurs by the reaction of the carbonyl groups with a tetraamine monomer. Cross-linking of the resulting polymers chains is accomplished by reaction of the furan end-cap group in a Diels-Alder reaction with a bis(dieneophile) substantially aromatic in composition.

Bis(benzil) type compounds containing one or two furan moieties

Preparation of a novel heterocyclic peri acid is initiated by reacting diaminodimethylbiphenyl with methyl vinyl ketone to produce tetramethyl biquinoline. The substituent methyl groups are oxidized subsequently to produce a tetraacid, or upon dehydration of the tetraacid, a dianhydride. The peri acids of this invention have the following structural formula: ##SPC1## Where R may be either ##EQU1## or (--COOH).sub.2 and R' is

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Manhattan Beach, CA, United States of America

Michael K O'Rell