In this study, hydrothermal extraction
experiments were performed in a semibatch apparatus at varying temperatures
and different extraction times to determine the optimum operating
conditions for the removal of oligomers from poly(ethylene terephthalate)
(PET) resins. High-molecular-weight PET in pellet form (M
w: 100 kDa) was used as the raw material. The results
obtained suggest that hydrothermal treatment enables partial extraction
of oligomers from PET resins. Using theoretical methods and the experimental
data, we calculated the maximum reaction time at each temperature,
considering the potential for application in plastic processing. A
maximum extraction efficiency of 16% was achieved by hydrothermal
extraction at 200 °C for 10 minutes. This novel technique is
a promising tool for the development of a next-generation, low-oligomer,
eco-friendly method in a short time.