Molecular Weight Optimization of Solid-State Polymerized Poly (ethylene terephthalate) Using Box-Behnken Statistical Design

Solid-state polymerization (SSP) is a post-condensation step that takes place in solid phase of polyethylene terephthalate (PET). SSP is normally conducted between glass transitiontemperature and melting point of polymer in order to efficiently increase the molecular weight of polymer [1]. Awide range of process parameters such as type and concentration of catalyst, process temperature, concentration of carboxyl end groups, and crystallinity of polymer affectfinal properties of the solid-state polymerized PET [2-3]. The aim of present work is optimization of crystallizationconditions and SSP time to maximize the number-average molecular weight ( n M ) of the PET. All experiments were conducted in a home made laboratory scale fluidized bed reactor