abstract Due to the increasing consumption of polymeric materials made of poly(ethylene terephthalate) (PET) in a variety of soft drink bottles and mineral water and packaging supplies, recycling of these materials is essential. ¬¬¬¬One of the methods of ¬PET recycling is the production of polyester solid and hollow fibers of recycled type. ¬According to the studies, despite of the significant development of recycled hollow polyester fibers, no significant scientific research has been conducted to study these¬ fibers. Therefore, in this study, the effect of some process parameters such as cooling air velocity in the melt spinning, the tensile ratio of the first area and the temperature of the fiber dryer on the morphology of hollow polyester fibers produced from recycled poly(ethylene terephthalate) by melt spinning method was¬¬¬¬ discussed. For this purpose, two types of fibers with finesse of 7 and 20 deniers with four different tensile ratios, three different cooling air velocity and two different temperatures in the fiber dryer were produced in Isfahan Zarlif Fiber Company. ¬¬The produced fiber samples were studied to investigate the effect of applied parameters from the perspective of linear density, tensile strength, elongation at break and number of crimp per unit length. ¬Differential scanning calorimetry (DSC) method was used to eva‎luate the thermal properties of the produced fibers and X-ray diffraction ¬ (XRD) was used to eva‎luate the crystalline structure of the samples. In the tests,¬ it was observed that increasing the tensile ratio reduced linear density and elongation at break, increased strength and crystallinity, and somewhat increased the number of crimp per unit length of fibers. The increase in the cooling air velocity resulted in a significant increase¬ in the number of crimp per unit length of fibers. Increasing the temperature of ¬the fiber dryer also increased linear density, decreased tensile strength and increased peak intensity in X-ray diffraction diagram. Keywords: Recycled hollow polyester fibers, melt spinning, poly(ethylene terephthalate), morphology

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