Abstract: A method of preparing a polycarbonate composition in a polymerization system that includes a monomer mixing unit, an oligomerization section, and a polymerization section. The method includes melt polymerizing a dihydroxy compound with a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst to produce the polycarbonate composition having a phosphorus-containing byproduct of at least one of the quaternary phosphonium catalyst or of the diaryl carbonate compound. The method further includes recycling the phosphorus-containing byproduct into the monomer mixing unit of the polymerization system and removing the polycarbonate composition from the polymerization system. The recycle stream has a phosphorus concentration of greater than or equal to 40 parts per million by weight.

Abstract: A method of preparing a polycarbonate composition, including: melt polymerizing in a polymerization unit a dihydroxy compound with a diaryl carbonate and removing a stream of color inducing species containing an isopropenyl phenyl-containing group from the polymerization unit, to form a polycarbonate composition, wherein the polycarbonate has a color inducing species containing an isopropenyl phenyl-containing group level below 170 ppm is provided.

Abstract: A method of preparing a polycarbonate composition in a polymerization system that comprises a monomer mixing unit, an oligomerization section, and a polymerization section. The method includes melt polymerizing a dihydroxy compound with a diaryl carbonate compound in the presence of a quaternary phosphonium catalyst to produce the polycarbonate composition having a phosphorus-containing byproduct of at least one of the quaternary phosphonium catalyst or of the diaryl carbonate compound. The method further includes recycling the phosphorus-containing byproduct into the monomer mixing unit of the polymerization system and removing the polycarbonate composition from the polymerization system. The recycle stream has a phosphorus concentration of greater than or equal to 40 ppm.

Abstract: A method of preparing a polycarbonate composition, including: melt polymerizing in a polymerization unit a dihydroxy compound with a diaryl carbonate and removing a stream of color inducing species containing an isopropenyl phenyl-containing group from the polymerization unit, to form a polycarbonate composition, wherein the polycarbonate has a color inducing species containing an isopropenyl phenyl-containing group level below 170 ppm is provided.

Abstract: A rotary vacuum filter for separation of bisphenol A-phenol adduct crystals from a crystallization liquor is provided. The rotary vacuum filter includes a filter drum with a perforated sector on a lateral surface of the filter drum; a non-polymeric filter cloth attached to the filter drum and covering said perforated sector; and a vacuum pump in fluid communication with an interior surface of the perforated sector. Methods and uses of thereof are also provided.

Abstract: Polymerization processes comprising melt polymerizing a carbonate and a dihydroxy compound in the presence of an amount of a beta organic catalyst so as to give rise to a polycarbonate product, wherein the amount of beta organic catalyst comprises at least one onium salt and also comprises triphenyl phosphonium oxide (TPPO), and wherein the TPPO represents less than about 0.3 weight % of the sum of the weights of the at least one onium salt and the TPPO in the amount of beta organic catalyst.

Abstract: Provided are polymerization processes, comprising melt polymerizing a carbonate and a dihydroxy compound in the presence of an amount of a beta organic catalyst so as to give rise to a polycarbonate product, wherein the amount of beta organic catalyst comprises at least one onium salt and also comprises tetraphenyl phosphonium oxide (TPPO), and wherein the TPPO represents less than about 0.3 weight % of the sum of the weights of the at least one onium salt and the TPPO in the amount of beta organic catalyst.