Hughes Aircraft Company

William E Elias

Susan L Oldham

Thomas K Dougherty

Kreisler S Lau

Stephen J Bigus

Richard Noel Leyden

Marvin B Klein

Alan R Kost

Robert Lawrence

Francis O Duane

Timothy C Thelander

Ephraim H Catsiff

Mahesh N Bhavnani

Wilson A Holland

An improved process is provided for making optical limiters having a graded axial distribution of a reverse saturable absorber compound, such as a buckminsterfullerene, in a host matrix, such as polymethyl methacrylate or polycarbonate. The process of the invention includes: (a) dissolving the reverse saturable absorber and the host matrix in a suitable solvent to form a solution having a preselected ratio of reverse saturable absorber to host matrix; (b) casting the solution onto a surface to form a film; (c) evaporating the solvent to form a free-standing film; (d) performing steps (a)-(c) for each different desired ratio of reverse saturable absorber to host matrix; (e) stacking the free-standing films in a desired order; and (f) hot-pressing the stack to form the optical limiter having a graded distribution of the reverse saturable absorber in the host matrix. If desired, the stack of films can be placed in a die for hot-pressing. The films can be pre-cut to the shape of the die.

Process for making a solid optical limiter containing a graded

A resin composition for investment casting contains a moderate boiling temperature liquid inert diluent, having a boiling point in the range of about 200.degree. to 300.degree. C. The presence of the liquid inert diluent allows the resin to be used as a pattern, or model, in investment casting by preventing breaking of the mold during burnout of the resin. Any of the conventional resins suitable for stereolithography may be employed in the practice of the invention. To the resin is added a moderate boiling point solvent in the amount of about 5 to 30 wt %. Use of the moderate boiling point solvent in conjunction with the resin allows the pattern to shrink and crack at moderate temperature before final burnout. The shrinkage occurs faster and at a lower temperature as compared to the prior art.

Resin composition and process for investment casting using

Novel acetylene-terminated silicone monomers with (a) silane (Si--H) functionalities, (b) silanol (Si--OH) functionalities, or (c) (alpha,omega)phenylethynyl terminated siloxanes, and a novel synthetic route. The (alpha,omega)phenylethynyl-terminated siloxane monomers are prepared, starting with 1,3-bromobenzene, which is converted to 3-TMS-ethynylbromobenzene, where TMS represents the trimethylsilyl group, by reacting 1,3-dibromobenzene with trimethylsilylacetylene and triethylamine in the presence of a palladium catalyst. The 3-bromo-TMS protected phenyl acetylene is then reacted with an alkyllithium compound, such as n-butyllithium, or with magnesium to form the corresponding lithio or Grignard compound, respectively, followed by reaction with a halogenated compound, such as chlorodimethylsilane, to form 3-trimethylsilyl-ethynylphenyldimethyl silane. Next, the TMS protected ethynylphenyl silane is subjected to deprotection and methanolysis of the Si--H bond to form 3-ethynylphenyldimethyl methoxy silane, employing methanol. This silane is then hydrolyzed to form the corresponding silanol. Finally, the silanol is then condensed by known methods to form the disiloxane. The disiloxane monomer can be reacted with a cyclic siloxane, having .gtoreq.3 silicon atoms, each independently substituted with hydrogen, C.sub.1 to C.sub.6 alkyl, phenyl, or phenyl substituted with one or more alkyl or halogen groups, to form oligomers. Both monomers and oligomers form thermoset polymers by heating to a temperature of at least about 250.degree. C.

(alpha, omega)phenylethynyl siloxane monomers, oligomers, and polymers

A fluxless solder for application to metal surfaces which include contaminants such as metal oxides. The fluxless solder includes a reducing agent which reacts with interfering metal oxides to form essentially inert compounds which require no further cleaning. Reducing agents, such as lithium, calcium, strontium and cesium are disclosed for use in lead-tin solders, in amounts ranging from about 0.5 to 10 atom percent. Various methods for forming the fluxless solder are also disclosed.

Fluxless solder

Epoxy end-capped oligomers of 1,3-diolefin compounds of Formula I ##STR1## These oligomers are formed by: (a) reacting a 1,3-diolefin compound having 4 to 12 carbon atoms per molecule with a difunctional initiator comprising anionic reactive sites to form an intermediate living oligomer comprising two anionic end groups; and (b) reacting the intermediate living oligomer with a halohydrin compound to epoxidize the two anionic end groups and form the desired oligomer. The oligomers are subsequently reacted with an epoxidizing agent to form a polymer having epoxy-derived linkages at regular intervals along the chain of the polymer.

Epoxy end-capped diolefin derivatives, polymers thereof, and processes

A new group of silane compounds in which silicon atoms are linked together by a hydrocarbon chain and which comprise phenyl groups substituted with an epoxy group or an ethenyl group. The compounds of the present invention have the formula ##STR1## where R.sub.1 is selected from the group consisting of: (a) an aliphatic hydrocarbon group containing 2 to 10 carbon atoms, and

Substituted aromatic silane compounds and method for preparation of same

Improvement in the method for preparing resin compositions for use as a laminate material in printed wiring boards wherein the resin composition is formed by mixing an epoxy-anhydride prepolymer with maleated polybutadiene and a suitable solvent. The improvement involves preparing the epoxy-anhydride prepolymer using a two step procedure instead of a single step. The two step procedure prevents uncontrolled exothermic reactions from occurring during preparation of commercial quantities of the epoxy-anhydride prepolymer and increases the versatility of the process since different anhydrides can be used in each of the two steps.

Polybutadiene-epoxy-anhydride laminating resins

Methods for forming small diameter holes in polyimide/Kelvar.RTM. substrates utilize hot concentrated sulfuric acid and then honing, as necessary, with liquid abradant slurries to smooth uneven edges of the openings.

Method for selectively forming small diameter holes in polyimide/Kevlar

A method for rendering a substrate resistant to erosion by a plasma comprising oxygen by providing on the surface of the substrate a layer of a cured polymer of a compound having the formula ##STR1## where: R.sub.1 is selected from the group consisting of:

Aromatic silane polymer coatings

A new group of silane compounds in which silicon atoms are linked together by a hydrocarbon chain and which comprise phenyl groups substituted with an epoxy group or an ethenyl group. The compounds of the present invention have the formula ##STR1## where R.sub.1 is selected from the group consisting of:

Epoxysilicone compounds are prepared by first reacting a dibromobenzene compound with magnesium in anhydrous ether solvent to form a Grignard reagent and subsequently reacting the Grignard reagent with allyl bromide to form a (bromophenyl)propene compound. Next, the (bromophenyl)propene compound is converted to the corresponding Grignard reagent, which is then reacted with a compound of the formula I below ##STR1## where n=1 to 6,

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El Segundo, CA, United States of America

William E Elias