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CATALYTIC TRIMERIZATION OF AROMATIC NITRILES

AND TRIARYL-S-TRIAZINE RING CROSS-LINKED HIGH TEMPERATURE RESISTANT POLYMERS AND COPOLYMERS MADE THEREBY

NASA Case No. LEW-12053-1

Address inquiries to:

Canada, France, Great Britain,
Japan, Sweden, West Germany

Lewis Research Center
Attn: Patent Counsel
Mail Code: 500-113
21000 Brook park Road
Cleveland, OH 44135

(Corresponding U.S. Patent-Application Pending)

Prior trimerization methods are unsuitable for processing the aromatic nitrile-modified (terminated and/or appended) condensationtype prepolymers into s-triazine ring cross-linked high temperature resistant matriz resins for fiber reinforced composites. With this invention, aromatic nitriles such as p-cyanobenzoic acid and its esters, etc. can be directly trimerized to their corresponding triaryl-s-triazines at moderate temperature and pressure. Also, with this invention, the norborene groups on the addition-type polyimides are replaced by aromatic nitrile groups, or part of the monomeric reactants (aromatic diamines and tetracarboxylic acid dianhydride or their derivatives) of those soluble high molecular weight polyimides having relatively low thermal stability were replaced by nitrile appended aromatic diamines and aromatic tetracarboxylic acid dianhydrides or their derivatives. These terminating and/or appending aromatic nitrile groups are then catalytically trimerized to produce new triaryl-s-trazine ring containing or cross-linked polyimides which possess the outstanding thermal stability of both polyimides and aryl-s-triazines for continuous use at temperatures above 315°C.

METHOD OF IMPROVING IMPACT RESISTANCE
OF CERAMIC BODIES, AND IMPROVED BODIES

NASA Case No. LEW-12301

Address inquiries to:

Canada, France, Great Britain,
Japan, Sweden, West Germany

Lewis Research Center
Attn: Patent Counsel
Mail Code: 500-113
21000 Brook park Road
Cleveland, OH 44135

(Corresponding U.S. Patent-Application Pending)

A difficulty with the proposed uses of ceramic materials for such high temperature applications as the stator vanes in aircraft and stationary gas turbines, and rotating parts in automotive gas turbines is their relatively low impact resistance. This invention is a method of improving the impact resistance of bodies of polycrystalline ceramic such as alumina, silicon nitride and silicon carbide, and bodies produced by the method. The body is provided with a layer of a low elastic modulus polycrystalline ceramic material which has microcracks therein, formed by such factors as thermalexpansion coefficient anisotropy, differences in thermalexpansion coefficients between phases of the material, and by changes in volume during phase transformations in the material. The layer can be applied by preforming the layer and then applying, or by hot pressing the material of the layer onto the body.

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Difficulties are often encountered in spacecraft assembly operations because of the existence of torsional stresses induced as a consequence of the tightening of certain bolts employed during such assembly operations. The present invention is a gear head wrench for applying torque to bolts without transferring torsional stresses to bolt-receiving structures. The wrench has an outer housing adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-reciving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress.

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Raw sewage treatment plants using conventional processes are finding it difficult to dispose of sludge solids. This invention utilizes a series of steps wherein the amount of final product is vastly reduced. The non-dissolved material is pyrolyzed to form an activated carbon and ash material. This carbon and ash is added to the sewer water and absorbs the organic matter and heavy metal ions dissolved in the water. Constant recycling of the carbon and ash reduce the amount of residual material to be disposed.

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It has become essential that the gasses in smokestack plumes and the like be monitored for the presence of pollutants such as NO, NO2, CO, CO2, SO2, and Oz. In this invention, a laser source excites the atmospheric area of the pollutants until the beam causes the pollutants to fluoresce and emit a return signal to a detector. Analysis of this signal as compared to a known standard yields a signal indicative of the magnitude of the pollutant being analyzed.

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