Blends of poly(propylene carbonate) and poly(methyl methacrylate) and their use in decomposition molding

摘要

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).