摘要:
A process is described for producing a coupled polymer by anionically polymerizing monomers selected from the group consisting of a vinyl aromatic hydrocarbon, a conjugated diene or both with an organo alkali metal compound to produce living polymer arms which are then contacted with a fullerene which reacts with the living polymer arms to form a coupled polymer. The coupled polymer has a novel composition and novel characteristics.
摘要:
A hydrogenation catalyst prepared by combining a Group VIIIA metal compound and a hydrocarbyl-substituted silicon alumoxane and a hydrogenation process wherein said catalyst is used to hydrogenate compounds containing ethylenic and/or aromatic unsaturation. The Group VIIIA metal compound is selected from the group of compounds consisting of carboxylates, chelates, alkoxides, salts of hydrocarbon acids containing sulfur and salts of partial half esters of hydrocarbyl acids containing sulfur. Nickel, cobalt and palladium compounds are particularly preferred for use in the hydrogenation catalyst. Hydrogenation catalysts prepared with hydrocarbyl-substituted silicon slumoxanes initially exhibit less hydrogenation activity than catalysts known heretofore in the prior art and prepared with a metal alkyl of a metal selected from Groups, I, II and III. These catalysts, then afford greater control over the extent of hydrogenation, particularly when partial hydrogenation is a desired end result. Ultimately, however, the catalyst permits substantially complete hydrogenation of both ethylenic and aromatic unsaturation.
摘要:
A process for selectively hydrogenating a polymer containing ethylenic unsaturation and cyano groups with a catalyst prepared by combining one or more of certain palladium compounds and one or more of certain aluminum compounds in a suitable solvent or diluent. The hydrogenation is accomplished in a suitable solvent for the polymer at a temperature within the range from about 20.degree. C. to about 175.degree. C. at a total pressure within the range from about 50 to about 1,000 psig and at a hydrogen partial pressure within the range from about 50 to about 950 psig. The hydrogenation can be accomplished so as to convert at least about 85% of the ethylenic unsaturation contained initially in the polymer without converting a significant portion of the cyano groups to amine groups. Best results are achieved when the catalyst is prepared by combining the one or more palladium compounds and the one or more aluminum compounds in proportions such that the Al:Pd atomic ratio is within the range from about 0.3:1 to about 0.9:1. Catalysts prepared in an ether solvent or diluent are more active than catalysts prepared in hydrocarbon solvents or diluents.
摘要:
A process for preparing a supported molybdenum carbide composition which comprises impregnating a porous support with a solution of molybdic acid dissolved in aqueous ammonium hydroxide, drying the impregnated support and then heating in a carbiding atmosphere at a temperature of about 650.degree.-750.degree. C.
摘要:
A process for preparing a supported tungsten carbide composition which comprises first forming a supported tungsten oxide composition, converting the oxide to the nitride by heating in an ammonia atmosphere, and then converting the nitride to the carbide by heating in a carbiding atmosphere.
摘要:
This invention relates to anionically polymerized block copolymers comprised of at least one block polyethylene and at least one block of a polymerized cyclic siloxane monomer, e.g., polydimethylsiloxane. Block copolymers with multiple "arms" may be formed by coupling these living diblocks with polyfunctional coupling agents. One copolymer for use in wax release coatings has an overall weight average molecular weight of 1500 to 100,000, a polyethylene block weight average molecular weight of less than 4100, and a polyethylene content of less than 55 percent by weight. Another copolymer for use in extruded release coating films prepared by blending the copolymer with a film grade polymer has an overall molecular weight of less than 20,000 and a polyethylene block molecular weight of less than 3700.
摘要:
A graft block copolymer is comprised of a completely saturated olefinic backbone with pendant anionic polymer side chains. The polymer is produced by copolymerizing an .alpha.-olefin with a monomer which contains a functional group which can be metallated so an anionic monomer can be polymerized therefrom, metallating the copolymer by reaction with metal alkyl or aryl compound and a metallation activator, and growing anionic polymer side chains from the copolymer backbone by reacting an anionically polymerized monomer with the metallated copolymer.
摘要:
A method for producing asymmetric radial polymers which comprises anionically polymerizing an anionically polymerizable monomer to form a first set of living polymer arms, coupling the first set of living polymer arms with a silicon-based coupling agent, substantially completing the coupling reaction, anionically polymerizing, in the presence of the coupled first set of polymer arms, a different anionically polymerizable monomer(s) to form a second set of living polymer arms, and adding a coupling activator and coupling the second set of living polymer arms to the coupled first set of polymer arms to form the asymmetric radial polymer.
摘要:
Radial or star asymmetric block copolymer of the following formulae and improved adhesive and sealant compositions containing them(I) (A--HD).sub.x --Y--(UD).sub.z or (II) (UD--A--HD).sub.x --Y or (III) ((UD).sub.y --A--HD).sub.x --Y--(UD).sub.zwherein A is a vinyl aromatic hydrocarbon block having a molecular weight of from 4000 to 20,000, HD is a hydrogenated conjugated diene block having a molecular weight of from 10,000 to 100,000, Y is a multifunctional coupling agent, UD is an unhydrogenated conjugated diene block having a molecular weight of from 1000 to 80,000, x is an integer from 2 to 20, y is 0 or 1, z is an integer from 1 to 10, and x+z ranges from 3 to 30.
摘要:
The present invention is an improvement upon the process for making block copolymers of vinyl aromatic hydrocarbons and/or conjugated dienes, and polydimethylsiloxane by first anionically polymerizing the vinyl aromatic hydrocarbon to make a living polymer block and then adding hexamethylcyclotrisiloxane and a polar promoter to polymerize a polydimethylsiloxane block at the end of the living polymer block. The improvement comprises reacting the living polymer blocks with a crossover reagent to decrease the crossover time from the living polymer block polymerization to the polydimethylsiloxane polymerization.