Abstract: Macrocyclic polyester oligomers are converted to linear polyesters by contact at a temperature of about 160.degree.-300.degree. C. with a cyclic titanium catalyst such as di-(1-butyl)-2,2-dimethylpropane-1,3-dioxytitanate, bis(2,2-dimethyl-1,3-propylene) titanate or 1-(1-butoxy)-4-methyl-2,6,7-trioxa-1-titanabicyclo[2.2.2]octane. Such catalysts have high activity and produce linear or branched polyesters of very high molecular weight.

Abstract: Macrocyclic polyester oligomers are converted to linear polyesters by contact at a temperature of about 160.degree.-300.degree. C. with a cyclic titanium catalyst such as di-(1-butyl)-2,2-dimethylpropane-1,3-dioxytitanate, bis(2,2-dimethyl-1,3-propylene)titanate or 1-(1-butoxy)-4-methyl-2,6,7-trioxa-1-titanabicyclo[2.2.2]octane. Such catalysts have high activity and produce linear or branched polyesters of very high molecular weight.

Abstract: Macrocyclic polyester oligomer compositions comprising alkylene isophthalate or terephthalate units or the like are prepared by the reaction of a diol with a diacid chloride in the presence of at least one amine characterized by substantially no steric hindrance around the basic nitrogen atom. The reaction is conducted under substantially anhydrous conditions and at a temperature from about -25.degree. to about +25.degree. C. The resulting macrocyclic oligomers may be converted to linear polyesters by contact with catalysts including basic reagents, stannous alkoxides, organotin compounds, titanate esters and metal acetylacetonates.

Abstract: Cyclic tin catalysts are employed for the preparation of branched polyesters from macrocyclic polyester oligomers.

Abstract: Cyclic tin catalysts are employed for the preparation of branched polyesters from macrocyclic polyester oligomers. They are less susceptible than previously known catalysts to the presence of acidic impurities in the oligomer compositions.

Abstract: Novel trisstannoxanes are prepared by the reaction of a dialkyltin oxide with a trihydroxy compound such as 1,1,1-tris(hydroxymethyl)propane. They may be employed as catalysts for the preparation of branched polyesters from macrocyclic polyester oligomers. They are less susceptible than previously known catalysts to the presence of acidic impurities in the oligomer compositions.

Abstract: A process for making thermoplastic polyester foams comprises the steps of subjecting macrocyclic polyester oligomer precursors to initiators and blowing agents at a constant operating temperature in order to produce foams which unexpectedly display low foam densities.

Abstract: The crystallinity of polyesters prepared from macrocyclic poly(1,4-butylene terephthalate) oligomers is reduced and cracking of molded parts suppressed by the incorporation therein of at least one other linear or macrocyclic poly(alkylene dicarboxylate) oligomer, such as poly(ethylene terephthalate) or poly(1,4-butylene isophthalate). It is preferably employed in macrocyclic form. The resulting compositions can be combined with inert fillers and polymerized.

Abstract: Intimate blends of macrocyclic oligomer compositions, such as cyclic polycarbonate or poly(alkylene dicarboxylate) oligomer mixtures, are blended with linear polymers, especially addition polymers. The blends flow easily and are frequently homogeneous. The macrocyclic oligomers therein may be polymerized to produce resin blends having advantageous properties.

Abstract: Thermoplastic polyester composites are prepared from compositions comprising a filler, at least one macrocyclic poly(alkylene dicarboxylate) oligomer and a polymerization catalyst therefor. The use of polyester oligomer mixtures is preferred, and they may be present in liquid or solid form. The polyester composites prepared therefrom are characterized by excellent properties including solvent resistance.

Abstract: Polymeric compositions are described which result from blending a mixture comprising: (A) at least one amorphous polycarbonate; (B) at least one cyclic polycarbonate oligomer containing hydroquinone carbonate structural units; and (C) at least one polycarbonate formation catalyst.The polymeric compositions have particular application in the preparation of shaped articles for use in environments characterized by the presence of solvents, solvent vapors, and/or potential for fire conditions. Methods for increasing the solvent and flammability resistance of amorphous polycarbonates are also described.

Abstract: Polymeric compositions are described which result from blending a mixture comprising: (A) at least one amorphous polycarbonate; (B) at least one linear polycarbonate oligomer containing hydroquinone carbonate structural units; and (C) at least one polycarbonate formation catalyst.The polymeric compositions have particular application in the preparation of shaped articles for use in environments characterized by the presence of solvents, solvent vapors, and/or potential for fire conditions. Methods for increasing the solvent and flammability resistance of amorphous polycarbonates are also described.

Abstract: Blended polymer compositions are described which comprise: (A) at least one amorphous polycarbonate; and (B) at least one linear polycarbonate oligomer containing hydroquinone carbonate structural units.The blended polymer compositions having particular application in the preparation of shaped articles for use in environments characterized by the presence of solvents, solvent vapors, and/or potential for fire conditions. Methods for increasing the solvent and flammability resistance of amorphous polycarbonates are also described.