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 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.