) were constant and continuously monitored during an operating time corresponding to three times of the residence time before the test evaluation. The pressure was fixed for every experimental test using different screw speeds. The mass flow was determined at different pressure conditions (from 2.68 to 4.14 kg/cm2) and temperatures (i.e., 260, 280, 290 and 300oC) for the two different raw materials: recycled PET (VI=0.65) and pharma grade PET (VI=0.71). The results obtained from the mathematical modeling were compared with those obtained from the experimental tests.
Finally, the fibers obtained using virgin and recycled PET were mechanically characterized. Specifically, the tensile properties were determined using an Instron machine (model 4011) in accordance with ASTM D 638-10. Also, the average molecular weight was evaluated using the viscosimetric approach and the micrographs were obtained using a scanning electron microscope HITACHI TM-1000.