Solid‐state polycondensation of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. I.

Poly(ethylene terephthalate) (PET), taken from postconsumer soft‐drink bottles, was subjected to solid‐state polycondensation, as received or after dissolution in various solvents and precipitation in methanol. The solvents used were: benzyl alcohol, phenol/tetrachloroethane 60/40, or o ‐chlorophenol. The effect of various reaction parameters, such as reaction temperature (180, 200, 220, and 230°C), and time on intrinsic viscosity [η] and carboxyl and hydroxyl end‐group content have been investigated. During the solid‐state polycondensation of PET that was used as received, both esterification and transesterification took place at all temperatures, while in PET samples, used after dissolution, the transesterification was observed only at 230°C. The highest number average molecular weight, M n = 60,200, was obtained from PET with initial M n = 20,300, dissolved in o ‐chlorophenol, after solid‐state polycondensation at 230°C for 8 h.