Polyethylene teraphtalate (PET) is one of the most commonly used commercial polyester for textile and other applications. In the year 2000, a total amount of about 30 millions tons of PET was com- mercially produced in worldwide including packing. In the past decade, annual growth of PET applica- tions is anticipated 5–6% for the textiles and about 5% for packaging applications [1]. The most of PET polymer is used in the field of textiles. Polyester fibers ranked the first place in the worldwide production of synthetic textile fibers with an output of 18.9 million tons which corresponds to 60% of market share [2] where the worldwide production of synthetic textile fibers was 32.995 million tons in the year of 2000. Among the polyester fibers, PET fibers have