Production of polyethylene teraphtalate (PET) fiber in the world is increasing every year and
reached to an amount of about 20 million tons a year in 2001. The wastes occur in the
production of PET fiber in the amount of about 3–5% of total production. The PET does not
degrade for a long time in nature. Since PET is a derivative of petroleum, the wastes of PET
are valuable and must be recycled. One of the recycling method of PET wastes is re-melting.
Thus, various properties of the PET wastes were improved using the re-melting method by
employing an extruder manufactured for the work. Degradation during re-melting decreases
the properties of the final product. The results indicate that the properties of recycled PET
wastes can be monitored by designing the parameters of the extruder. Also, the further degradation
of the material can be prevented and the recycling costs are minimized.