The solid state postcondensation of PET, 1 - A review of the physical and chemical processes taking place in the solid state

A review of the processes underlying the solid state postcondensation of poly(ethylene terephthalate) (PET) is presented. Fundamental aspects of the reactions are treated, and it is shown that the rate of polycondensation in the solid state depends on the relative rates of two types of diffusion. On the one hand, the diffusion of reaction by-products (physical diffusion) controls the rate of the forward reactions.