Abstract: A process for crystallizing a polyester polymer by introducing a molten polyester polymer, such as a polyethylene terephthalate polymer, into a liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer, such as at a temperature ranging from 100° C. to 190° C., and allowing the molten polyester polymer to reside in the liquid medium for a time sufficient to crystallize the polymer under a pressure equal to or greater than the vapor pressure of the liquid medium. A process flow, underwater cutting process, crystallization in a pipe, and a separator are also described.

Abstract: A process for crystallizing a polyester polymer by introducing a molten polyester polymer, such as a polyethylene terephthalate polymer, into a liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer, such as at a temperature ranging from 100° C. to 190° C., and allowing the molten polyester polymer to reside in the liquid medium for a time sufficient to crystallize the polymer under a pressure equal to or greater than the vapor pressure of the liquid medium. A process flow, underwater cutting process, crystallization in a pipe, and a separator are also described.

Abstract: A method for incorporating a UV light absorbing compound into a polyester prepared using direct esterification of reactants selected from a dicarboxylic acid and a diol. The method comprises reacting the reactants in an esterifying reactor under conditions sufficient to form an esterified product including at least one of an ester, an oligomer, or mixture having an ester and a mixture of low molecular weight polyester; polymerizing the esterified product in a polycondensation reactor to form a polyester; and adding the UV absorbing compound to the esterified products when at least 50% of the carboxy groups initially present in the reactants have been esterified to obtain a yield of UV absorbing compound incorporated into the polyester of greater than 25%. Articles utilizing the UV protected polyester prepared by the method of the invention are additionally disclosed.

Abstract: A process for crystallizing a polyester polymer by introducing a molten polyester polymer, such as a polyethylene terephthalate polymer, into a liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer, such as at a temperature ranging from 100° C. to 190° C., and allowing the molten polyester polymer to reside in the liquid medium for a time sufficient to crystallize the polymer under a pressure equal to or greater than the vapor pressure of the liquid medium. A process flow, underwater cutting process, crystallization in a pipe, and a separator are also described.

Abstract: A process for thermally crystallizing a polyester polymer by introducing pellets into a liquid medium having a temperature of at least 140° C. within a liquid medium zone and crystallizing the submerged pellets at or above the vapor pressure of the liquid medium without increasing the molecular weight of the pellets, and while the pressure on at least a portion of the pellets is equal to or greater than the vapor pressure of the liquid medium, separating at least a portion of said pellets and at least a portion of the liquid medium from each other. The crystallization is desirably conducted in the liquid medium zone without mechanically induced agitation. Optionally, the pellets are formed by an underfluid pelletizer.