Abstract In Polyethylene terephthalate (PET) processing the raw materials are purified terephthalic acid (PTA), moderately (MTA), monoehalene glycol (MEG). The of PTA is very difficult and costly. For reducing percent we using different percentages MTA blend in PET processing. affected properties polyester melt spinning process. such as elongation, tenacity, molecular chain length, b-color IV, ...