The United States of America As Represented by the Administrator of the

United Technologies Corporation

United States of America As Represented by the Administrator of Nasa

Other

The United States of America As Represented by the Administrator of

Ruth H Pater

Daniel A Scola

Norman J Johnston

Marion G Hansen

Renki Tashiro

A composite conductor includes a conductor that has a high temperature polyimide insulation formed around it. This polyimide layer may include reinforcing fibers such as, for instance, glass fibers. The insulation layer may further include grading layers. The conductor is placed inside an earth layer. The composite conductor may be protected with a stainless steel enclosure.

Composite insulated conductor

Polyimides having a desired combination of high thermo-oxidative stability, low moisture absorption and excellent chemical and corrosion resistance are prepared by reacting a mixture of compounds including (a) 3,3&prime;,4,4&prime;-benzophenonetetracarboxylic dianhydride (BTDA), (b) 3,4&prime;-oxydianiline (3,4&prime;-ODA), and (c) 5-norbornene-2,3-dicarboxylic anhydride (NA) in a high boiling, aprotic solvent to give 5 to 35% by weight of polyamic acid solution. The ratio of (a), (b), and (c) is selected to afford a family of polyimides having different molecular weights and properties. The mixture first forms a polyamic acid precursor. Upon heating at or above 300&deg; C., the polyamic acids form polyimides, which are particularly suitable for use as a high temperature coating, adhesive, thin film, or composite matrix resin.

Heat, moisture, and chemical resistant polyimide compositions and methods for making and using them

In the process of the present invention, a non-polar, aprotic solvent is removed from an oligomer/polymer solution by freeze-drying in order to produce IPNs and semi-IPNs. By thermally quenching the solution to a solid in a short length of time, the size of the minor constituent-rich regions is greatly reduced as they are excluded along with the major constituent from the regions of crystallizing solvent. The use of this process sequence of controlling phase morphology provides IPNs and semi-IPNs with improved fracture toughness, microcracking resistance, and other physical-mechanical properties as compared to IPNs and semi-IPNs formed when the solvent is evaporated rather than sublimed.

Process for controlling morphology and improving thermal mechanical

Process for controlling morphology and improving thermal-mechanical

A pharmaceutical composition suitable for the treatment of a condition selected from the group consisting of cardiovascular disease, cerebrovascular disease, Alzheimer's disease, depression or combinations thereof comprising various mixtures of the aqueous extracts of tissue of specific Chinese plants and herbs. A method of preparing the pharmaceutical compositions of the invention and a method for treating a patient therewith are also disclosed.

Compositions and method of treating cardio-, cerebro-vascular and

A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance and mechanical performance, when compared to the commercial Thermid.RTM. materials. This simultaneous semi-IPN was prepared by mixing a thermosetting polyimide with a thermoplastic monomer precursor solution (NR-15082) and allowing them to react upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene endcapped polyimides which were previously inherently brittle and difficult to process.

Tough, processable simultaneous semi-interpenetrating polyimides

A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance and mechanical performance, when compared to the commercial Thermid.RTM. materials. This simultaneous semi-IPN was prepared by mixing a thermosetting polyimide with a thermoplastic monomer precursor solution (NR-150B2) and allowing them to react upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene endcapped polyimides which were previously inherently brittle and difficult to process.

This invention is a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide having the following repeating unit. ##STR1## wherein Z=C or SO.sub.2. Provided is an improved high temperature matrix resin which is capable of performing in the 200.degree. to 300.degree. C. range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance and moisture and solvent resistances.

Tough high performance composite matrix

A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance and mechanical performance, when compared to the commercial Thermid.RTM. materials. This simultaneous semi-IPN was prepared by mixing the monomer precursors of Thermid.RTM. AL-600 (a thermoset) and NR-150B2 (a thermoplastic) and allowing the monomers to react randomly upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene end-capped polyimides which were previously inherently brittle and difficult to process.

Tough, processable semi-interpenetrating polymer networks from monomer

An improved low toxicity polymerization of monomer reactants (PMR) system has 3,4'-oxydianiline as the key monomer reactant. One variation of this system, LaRC-RP46, is prepared by reacting together monomethyl ester or 5-norbornene-2,3-dicarboxylic acid (NE), 3,4'-oxydianiline (3,4'-ODA), and dimethyl ester of 3,3',4,4'-benzophenonetetracarboxylic acid (BTDE); this combination is then treated with heat. This new matrix resin is readily processed into a high quality graphite fiber reinforced composite with excellent reproducibility. The flexibility of the ether linkage in 3,4'-ODA provides high toughness. The composite retains excellent mechanical properties both at 316.degree. C. and at 371.degree. C. The development of LaRC-RP46 will significantly extend the applications of PMR type polyimides.

Low toxicity high temperature PMR polyimide

This invention is a process for making a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide having the following repeating unit: ##STR1## Provided is an improved high temperature matrix resin which is capable of performing at 316.degree. C. in air for several hundreds of hours. This resin has significantly improved toughness and microcracking resistance, excellent processability and mechanical performance, and cost effectiveness.

Semi-interpenetrating polymer network for tougher and more microcracking

This invention is a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide having the following repeating unit: ##STR1## Provided is an improved high temperature matrix resin which is capable of performing at 316.degree. C. in air for several hundreds of hours. This resin has significantly improved toughness and microcracking resistance, excellent processability and mechanical performance, and cost effectiveness.

A tough, high performance polyimide is provided by reacting a triple bond conjugated with an aromatic ring in a bisethynyl compound with the active double bond in a compound containing a double bond activated toward the formation of a Diels-Adler type adduct, especially a bismaleimide, a biscitraconimide, or a benzoquinone, or mixtures thereof. Addition curing of this product produces a highly linear polymeric structure and heat treating the highly linear polymeric structure produces a thermally-stable aromatic addition-type thermoplastic polyimide, which finds utility in the preparation of molding compounds, adhesive compositions, and polymer matrix composites.

Tough, high performance, addition-type thermoplastic polymers

A low temperature processable moisture resistant polyimide and fiber reinforced composite of such a polymer and methods for making the same. The polyimide resin has repeating polymer units of the formula ##STR1## wherein n is 2 to about 20 and the molecular weight of the polymer chain is such that the polymer absorbs below about 0.2% by weight moisture at room temperature. The polyimide is made by reacting 4,4'(hexafluoroisopropylidene)bis(o-phthalic anhydride) with a diamine having the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2 wherein n is 2 to about 20 to form a polyamic acid. The polyamic acid is imidized to form the polyimide prepolymer and then further polymerized by exposing the polyimide prepolymer to heat to form the polymer described above. The composite can be made using the above process by coating fibers with the polyimide prepolymer, stacking layers of the coated fibers in a mold, and hot pressing the stacked impregnated fibers. The composite can also be made by coating fibers with 4,4'(hexafluoroisopropylidene)bis(o-phthalic anhydride) and a diamine as described above stacking layers of the coated fibers in a mold and hot pressing the stacked impregnated fibers.

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Tabb, VA, United States of America

Ruth H Pater