Abstract: A method for producing a transparent article comprises the steps of melt transesterifying a monomer mixture in the presence of a transesterification catalyst to produce a hydroquinone polycarbonate copolymer product comprising greater than 45 mole percent of structural units derived from the hydroquinone. The monomer mixture comprises a hydroquinone, at least one aromatic dihydroxy compound other than the hydroquinone, and a carbonic acid diester. The hydroquinone polycarbonate copolymer product is then heated to a highest processing temperature of 5° C. to 20° C. above a maximum melting melt temperature for the hydroquinone copolymer product for a sufficient period of time to render the hydroquinone polycarbonate copolymer product transparent upon cooling to ambient temperature; and cooling the hydroquinone polycarbonate copolymer product to produce the transparent article.

Abstract: A method for producing a transparent article is provided. The method comprises melt transesterifying in the presence of a transesterification catalyst and a monomer mixture to produce a biphenol polycarbonate copolymer product comprising greater than 45 mole percent of structural units derived from the biphenol by heating the monomer mixture to a temperature of greater than 340° C. to make the biphenol polycarbonate copolymer; and cooling the biphenol polycarbonate copolymer to produce the transparent article. The monomer mixture comprises the biphenol, at least one aromatic dihydroxy compound other than the biphenol, and an activated carbonic acid diester.

Abstract: A method for producing a transparent article comprises the steps of melt transesterifying a monomer mixture in the presence of a transesterification catalyst to produce a hydroquinone polycarbonate copolymer product comprising greater than 45 mole percent of structural units derived from the hydroquinone. The monomer mixture comprises a hydroquinone, at least one aromatic dihydroxy compound other than the hydroquinone, and a carbonic acid diester. The hydroquinone polycarbonate copolymer product is then heated to a highest processing temperature of 5° C. to 20° C. above a maximum melting melt temperature for the hydroquinone copolymer product for a sufficient period of time to render the hydroquinone polycarbonate copolymer product transparent upon cooling to ambient temperature; and cooling the hydroquinone polycarbonate copolymer product to produce the transparent article.

Abstract: A method for producing a transparent article is provided. The method comprises melt transesterifying in the presence of a transesterification catalyst and a monomer mixture to produce a biphenol polycarbonate copolymer product comprising greater than 45 mole percent of structural units derived from the biphenol by heating the monomer mixture to a temperature of greater than 340° C. to make the biphenol polycarbonate copolymer; and cooling the biphenol polycarbonate copolymer to produce the transparent article. The monomer mixture comprises the biphenol, at least one aromatic dihydroxy compound other than the biphenol, and an activated carbonic acid diester.

Abstract: Supercritical drying has distinct advantages in generating microcellular materials. The dimensional stability of the polymer is not affected on drying because the supercritical process does not go through the two phase path and therefore the effect of capillary forces is absent. This helps in maintaining the morphology of the final polymer structure and better control over cell size.Organic microcellular foams were prepared by polymerizing directly in a near-critical fluid and pursuing the supercritical drying in the same reactor. The critical variables are the choice of a diluent with a strong enough solvent power to stabilize the polymer matrix, but with a low enough critical temperature to permit critical point drying without damage to the polymer matrix.

Abstract: Supercritical drying has distinct advantages in generating microcellular materials. The dimensional stability of the polymer is not affected on drying because the supercritical process does not go through the two phase path and therefore the effect of capillary forces is absent. This helps in maintaining the morphology of the final polymer structure and better control over cell size.Organic microcellular foams were prepared by polymerizing directly in a near-critical fluid and pursuing the supercritical drying in the same reactor. The critical variables are the choice of a diluent with a strong enough solvent power to stabilize the polymer matrix, but with a low enough critical temperature to permit critical point drying without damage to the polymer matrix.