Thermal crystallization of a molten polyester polymer in a fluid

摘要

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 DEG C to 190 DEG 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.