Abstract: 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.

Abstract: 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.

Abstract: Polyimide prepolymers formed by thermo-reactions of an aliphatic bismaleimide, where the aliphatic group is a polyaliphatic ether, with an aromatic bismaleimide and/or an aromatic diamine in combination with a cross-linking agent having at least two vinyl groups provide compositions which are curable at low temperatures, i.e., 65.degree. C. or less.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A heat exchanger is provided having coiled tubing and radiating fins about which hot flue gases for the cooking equipment circulate to heat a medium passing therethrough. Temperature control valves are selectively adjustable to pass the heated water along either of two sets of conduits for heating makeup air or heating water for use in the facility, respectively. These temperature control valves are set so that when the ambient room temperature is less than 70.degree. F., the medium heated by the flue gases is passed through a second heat exchanger which intercepts incoming air to warm it before its admission in the building. When the temperature exceeds 70.degree. F., the valves automatically switch to direct the heated medium to a third exchanger for heating tap water. A bypass arrangement recirculates the heat carrying medium through the primary heat exchanger until it achieves a predetermined temperature to prevent condensation.

Abstract: 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.

Abstract: A rotatable cleaning element having a resilient, porous material disposed on the outer surface thereof is mounted in a foil bearing so that the surface of the porous material protrudes above the bearing surface. The interior of the bearing is maintained at a negative pressure, and a jet of pressurized air disposed within the rotatable element. When magnetic tape is transported over the bearing surface, the tape makes contact with and slightly compresses the porous material. As the cleaning element rotates successive areas of the porous material is brought into contact with the tape. Compression of the material causes the pores thereof to expand slightly, and engage foreign material on the tape surface. The pores contract as the material breaks contact with the tape to encapture the foreign material. The foreign matter thus accumulated is subsequently blown free of the porous material by a jet of air directed from within the rotatable body.

Abstract: Linear polymers are produced by the reaction of an olefinic end-capped bis(imide) or bis(amide) compound, i.e. a dieneophile with a furfuryl or furan end-capped bis(imide) or bis(amide) compound, i.e. a diene. These linear polymers have an alicyclic endooxy linkage repeated throughout the polymer backbone chain where the furfuryl end-cap combines with the olefin end-cap by Diels-Alder reaction. The linear polymer is converted to a higher performance polymer by heating in the range of 200.degree. to 400.degree.C whereupon the endooxy linkage is aromatized in situ. The resins so prepared are suitable for use in severe environments at temperatures up to 350.degree.C.

Abstract: Structurally stronger titanium articles are produced by a weld-bonding technique comprising fastening at least two plates of titanium together using spot-welding and applying a bead of adhesive along the edge of the resistance spot-welded joint which, upon heating, flows and fills the separation between the joint components.

Abstract: A low temperature curing polymeric adhesive composition may be made by reacting an amino alcohol having between 1 and 3 amino groups and between 2 and 5 hydroxyl groups with a stoichiometric amount of a carboxylic acid or derivative. Free radical catalysts and accelerators may be added to speed the cure of the adhesive. These adhesive resins can be cured at or near ambient room temperature and are highly desired for fabrication of bonded materials possessing long fatigue life because of reduced stresses that might be induced at higher cure temperatures. A generalized formula may be illustrated as follows: ##EQU1## WHERE R" may be hydrogen, alkyl, or cycloalkyl; R' may be hydrogen or alkyl; R is an alkyl; R.sub.1 may be hydrogen, an alkyl, or phenyl; m is an integer from 1 to 3; and n is an integer from 1 to 2.

Abstract: A compliant polyimide having superior thermal-mechanical properties can be produced by reacting an aromatic bis(furfurylimide) with an aliphatic ether bis(maleimide) via a Diels-Alder reaction. These polyimides display a long-term thermal-oxidative stability and a high percent recoverable elongation to break, and they are suitable for use as films, fibers, coatings, adhesives, structures, and sealants.

Abstract: This invention covers means in connection with magnetic recording devices, to position, latch and remove reels from a driving hub, and actuation means therefor. The hub onto which the tape reel is placed carries an elastic sleeve about which the reel is placed. An actuation rod which passes through the hollow shaft of the drive motor carries a spool, to which three link bars are hinged. These are in radial planes spaced at 120.degree. to each other. The link bars are attached respectively to three shoes which are adapted to press outward against the inside wall of the elastic sleeve, which expanded outward against, and securely grips the reel hub. Also involved in the linkages between the link bars and the shoes are three dogs, which are adapted to press the reel hub against the drive hub and/or to lift the reel hub, depending on the position of the actuator rod.

Abstract: A functionally terminated polybutadiene polymer is reacted with an epoxide to produce an epoxide terminated polybutadiene. A crosslinking agent and a peroxide free radical initiator are mixed with the epoxy terminated polybutadiene, and upon reaction, a thermoset resin is produced having advanced chemical, electrical, and thermomechanical properties.