Solid-State Polymerization of Bisphenol A Polycarbonate with a Spray-Crystallizing Method

A novel crystallization method for the production of high-molecular-weight bisphenol A polycarbonate by solid-state polymerization is suggested. In this method, a low-molecular-weight polycarbonate prepolymer is dissolved in a solvent and then partially crystallized with a novel spray-crystallizing method to prepare crystallized polycarbonate particles having a very uniform and porous structure with a narrow melting region. As a result, during solid-state polymerization, the phenol byproduct can be easily removed from the polymerizing porous polycarbonate particles, and the polymerization rate is dramatically increased. In particular, the effects of the crystallization methods on secondary crystallization during solid-state polymerization and the melting behavior have been investigated with differential scanning calorimetry studies. The final product, a high-molecular-weight polycarbonate, displays a very narrow molecular weight distribution and Uniform physical properties. A simultaneous process and an adequate reactor design for spray crystallization and solid-state polymerization are also suggested. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 883-889, 2009