Abstract: A method of making polycarbonate comprises polymerizing, in a melt polymerization reaction, an aromatic dihydroxy compound and a diaryl carbonate in a presence of a polymerization catalyst and producing a by-product vapor stream comprising the dihydroxy compound, the diaryl carbonate and a diaryl carbonate by-product, adding a low vapor pressure compound to the by-product vapor stream to produce a modified by-product vapor stream, introducing the modified by-product vapor stream to a separation unit, removing the volatile diaryl carbonate by-product from the modified by-product vapor stream in the separation unit to form a treated by-product stream and returning the treated by-product stream to the polymerization reaction. Alternatively, the low vapor pressure compound can be added directly to the separation unit.

Abstract: A method of making polycarbonate comprises polymerizing, in a melt polymerization reaction, an aromatic dihydroxy compound and a diaryl carbonate in a presence of a polymerization catalyst and producing a by-product vapor stream comprising the dihydroxy compound, the diaryl carbonate and a diaryl carbonate by-product, adding a low vapor pressure compound to the by-product vapor stream to produce a modified by-product vapor stream, introducing the modified by-product vapor stream to a separation unit, removing the volatile diaryl carbonate by-product from the modified by-product vapor stream in the separation unit to form a treated by-product stream and returning the treated by-product stream to the polymerization reaction. Alternatively, the low vapor pressure compound can be added directly to the separation unit.

Abstract: A method of making a polycarbonate is described. The method comprises reacting an activated diaryl carbonate and a dihydroxy compound at a reaction temperature in a reactor to form a reaction mixture wherein the reactor comprises a heated cover and an open space between the cover and the reaction mixture. The dihydroxy compound comprises a vapor pressure greater than or equal to 0.01 kiloPascals at the reaction temperature and the temperature of the open space in the reactor, the temperature of the cover, or the temperature of the open space and the cover is greater than or equal to the melt temperature of the monomer having the highest melt temperature.

Abstract: A method of forming polycarbonate includes the steps of introducing a plurality of reaction components to a reactor operating under melt polymerization conditions and removing ester-substituted phenol from the reactor. The plurality of reaction components include a dihydroxy compound, an ester-substituted diaryl carbonate, and a melt transesterification catalyst. The reaction components are introduced in a plurality of reaction component streams. A first reaction component streams includes a melt transesterification catalyst dissolved or suspended in a liquid carrier containing an ester-substituted phenol. The composition of the first reaction component stream is selected such that ester-substituted phenol is not generated as a reaction product in the first reaction component stream.

Abstract: A method of forming polycarbonate includes the steps of introducing a plurality of reaction components to a reactor operating under melt polymerization conditions and removing ester-substituted phenol from the reactor. The plurality of reaction components include a dihydroxy compound, an ester-substituted diaryl carbonate, and a melt transesterification catalyst. The reaction components are introduced in a plurality of reaction component streams. A first reaction component streams includes a melt transesterification catalyst dissolved or suspended in a liquid carrier containing an ester-substituted phenol. The composition of the first reaction component stream is selected such that ester-substituted phenol is not generated as a reaction product in the first reaction component stream.

Abstract: A method of producing a polycarbonate is provided. In an embodiment of the present invention the method includes the steps of: (i) introducing to a melt polymerization reactor system a reaction mixture having a first dihydroxy compound and an acid stabilizer, a carbonate source, and a polymerization catalyst system containing K2HPO4; and (ii) allowing the reaction mixture to polymerize thereby forming polycarbonate.

Abstract: A method of producing a polycarbonate is provided. In an embodiment of the present invention the method includes the steps of: (i) introducing to a melt polymerization reactor system a reaction mixture having a first dihydroxy compound and an acid stabilizer, a carbonate source, and a polymerization catalyst system containing K2HPO4; and (ii) allowing the reaction mixture to polymerize thereby forming polycarbonate.

Abstract: A polycarbonate composition comprises chloride, sulfate, phosphate or a combination of two or more of the foregoing ionic species in an amount of zero to about 100 parts per billion based on the total weight of the composition; and phenol, carbonic diester, aromatic dihydroxy compound or combination of two or more of the foregoing organic compounds in an amount of zero to about 500 parts per million by weight based on the total weight of the composition; wherein the polycarbonate has a weight average molecular weight of about 40,000 to about 90,000 dalton as determined by gel permeation chromatography using polystyrene standards and a melt volume rate of about 1 to about 35 cm3/10 minutes when measured at about 300° C. with a force of about 1.2 kilograms.