Abstract: The present invention relates to a novel process for the preparation of a linear monomer alkyl lactyl lactate by a simple esterification reaction of acid with ester in presence of suitable catalysts or reagents. The present invention further relates to a process for the preparation of poly acid from alkyl lactyl lactate by using suitable catalyst.

Abstract: The present invention relates to a novel process for the preparation of a linear monomer alkyl lactyl lactate by a simple esterification reaction of acid with ester in presence of suitable catalysts or reagents. The present invention further relates to a process for the preparation of poly acid from alkyl lactyl lactate by using suitable catalyst.

Abstract: A process for the synthesis of 100% optically pure L(+)-lactide catalyzed by zinc and tin metal catalysts of less than 150 micron particle size is disclosed. The L-lactide obtained was further purified to obtain lactide of 100% optical purity and acid impurities less than 10 meq/kg.

Abstract: Copolyester with improved transition temperature, melting temperature and crystallinity including units derived from lactic acid and isosorbide, where the ratio of lactic acid to isosorbide ranges from 99:1 to 50:50.

Abstract: Copolyester with improved transition temperature, melting temperature and crystallinity including units derived from lactic acid and isosorbide, where the ratio of lactic acid to isosorbide ranges from 99:1 to 50:50.

Abstract: A process for the synthesis of 100% optically pure L(+)-lactide catalyzed by zinc and tin metal catalysts of less than 150 micron particle size is disclosed. The L-lactide obtained was further purified to obtain lactide of 100% optical purity and acid impurities less than 10 meq/kg.

Abstract: Copolycarbonates containing such structural units as birefringence-reducing or “soft block” units are prepared by conducting a reaction, such as melt polymerization or equilibration, between a precursor polycarbonate and a monomer, polycarbonate oligomer or high molecular weight polycarbonate which is a source of other structural units. The crystallinity of the resulting precursor copolycarbonate or one of the reagents employed in its preparation is enhanced and the precursor copolycarbonate is subjected to solid state polymerization.

Abstract: Solid state polymerization of polycarbonates and polyesters is preceded by a step of contacting particles of an amorphous precursor polymer with a particulate material, typically a crystallized polycarbonate, which prevents adherence of the precursor polymer particles to each other. It is then possible to perform the solid state polymerization step without crystallizing the precursor polymer.

Abstract: Copolycarbonates containing such structural units as birefringence-reducing or "soft block" units are prepared by conducting a reaction, such as melt polymerization or equilibration, between a precursor polycarbonate and a monomer, polycarbonate oligomer or high molecular weight polycarbonate which is a source of other structural units. The crystallinity of the resulting precursor copolycarbonate or one of the reagents employed in its preparation is enhanced and the precursor copolycarbonate is subjected to solid state polymerization.

Abstract: Amorphous precursor polycarbonates, such as oligomers, are converted to high molecular weight polycarbonates in a unitary series of operations that includes contact with an alkanol having a boiling point up to about 180.degree. C. and heating the resulting wetted particles so as to effect solid state polymerization. Heating is at progressively increasing temperatures from below the boiling point of the alkanol to a final level between the Tg and the melting temperature of said enhanced crystallinity polycarbonate.

Abstract: Polycarbonates are recycled without the need for chemical modification by dissolution in a solvent followed by removal of any insoluble materials and precipitation by addition of a non-solvent. The precipitation step may be followed by solid state polymerization of the recycled polycarbonate. Particularly when solid state polymerization is to be performed, the use of a combination of solvent and non-solvent which produces a crystalline intermediate is performed, and use of a modifying reagent increasing the hydroxy end group concentration of the polycarbonate may be advantageous.

Abstract: The crystallinity of an amorphous precursor polycarbonate is enhanced by contact in the liquid or vapor state with a non-solvent which may be water, an alkanol or a mixture thereof and which is dialkyl carbonate-free. Contact temperatures are at least about 75.degree. C. and are further defined by the relationshipT.sub.c .gtoreq.T.sub.b -z,wherein T.sub.c is the contact temperature, T.sub.b is the boiling point of the non-solvent at the contact pressure employed (both in degrees C.) and z is a constant whose value is 60.

Abstract: Crystallization of precursor polycarbonates prior to solid state polymerization is achieved by contact with a non-solvent comprising, at least in part, a dialkyl carbonate such as dimethyl carbonate. The non-solvent can be a mixture, typically of dimethyl carbonate with water or an alkanol such as methanol.

Abstract: Solid state polycarbonate formation comprises an initial step of converting a precursor polycarbonate to an enhanced crystallinity precursor polycarbonate and a second step of polymerizing said enhanced crystallinity precursor polycarbonate in the solid state. Several options are employed. These include modifying the precursor polycarbonate by contact with a dihydroxy compound or diaryl carbonate, conversion of the precursor polycarbonate to the enhanced crystallinity polymer by contact with at least one compound selected from the group consisting of alkali metal hydroxides, tetraalkylammonium hydroxides, tetraalkylammonium carboxylates, tetraalkylphosphonium hydroxides and tetraalkylphosphonium carboxylates, and conducting the solid state polymerization in the presence of a catalytic amount of at least one tetralkylammonium or tetraalkylphosphonium carboxylate. The preferred tetralkylammonium compounds are tetramethylammonium maleate and tetramethylammonium hydroxide.

Abstract: An improved process for the preparation of aromatic polyesters, whereby dialkyl esters of aromatic dicarboxylic acids are melt-polymerized with aromatic bisphenol to furnish an amorphous poly(arylester) prepolymer. The amorphous poly(arylester) prepolymer is crystallized, separated, and dried to provide a crystallized poly(arylester) prepolymer, which is heated to yield the aromatic polyester.