Air Products and Chemicals, Inc.

James J Weber

Joseph G Santangelo

Lloyd Mahlon Robeson

Richard G Sinclair

Jeffrey A Kuphal

Daniel P Kramer

Richard D Tenaglia

Compositions useful in decomposition molding procedures such as destructive foam casting or ceramic or metallic powder sintering are provided by blends of polymers having greater than 50 weight percent propylene carbonate units and polymers having greater than 50 weight percent methyl methacrylate units. Such blends exhibit an unexpectedly even decomposition profile over the range of temperatures at which their constituent polymers each decompose relatively rapidly. The controlled decomposition rate reduces problems in destructive foam casting and ceramic or metallic powder molding caused by sudden release of gases by the foam pattern or the polymer binder. Preferred blends contain 35 to 65 weight percent poly(methyl methacrylate) and 65 to 35 weight percent poly(propylene carbonate), and very even decomposition behavior is exhibited by blends of 35 to 45 weight percent poly(methyl methacrylate) and 65 to 55 weight percent poly(propylene carbonate).

Blends of poly(propylene carbonate) and poly(methyl methacrylate) and

The present invention relates to a binder and a method for making and shaping a green body of ceramic powder and subsequently producing a formed ceramic body. The method of the present invention comprises admixing a ceramic powder with a binder comprising a polyalkylene carbonate to form a ceramic-binder mixture. The binder of the present invention comprises a polyalkylene carbonate, preferably polyethylene carbonate or polypropylene carbonate.

CO.sub.2 copolymer binder for forming ceramic bodies and a shaping

CO.sub.2 copolymer ceramic-binder composition

The present invention is a novel class of block copolymers and a process of making the same. An alkylene oxide is reacted with CO.sub.2 in an organic solvent in the presence of an organometallic catalyst to form a polyalkylene carbonate. A second alkylene oxide is subsequently added without the addition of catalyst. The resulting product is a block copolymer comprising distinct, covalently linked, alkylene carbonate blocks.

Process for producing novel block alkylene polycarbonate copolymers

Metal castings having reduced residual carbon ash and surface flaws are produced by an evaporative pattern casting process, in which an organic foam pattern is vaporized upon contact with a molten metal leaving a metal replica of the pattern. The organic foam used in this process comprises a polymer formed by polymerizing CO.sub.2 with one or more oxirane compounds.

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Allentown, PA, United States of America

James J Weber