The effect of spinneret cross-sectional shape on the physical and crimp properties of melt spun PET multifilament yarn

Today, different filament cross-sectional shapes of spinneret are used in the production of synthetic multifilament yarns to create various applications and properties. This research aimed to investigate the effect of round and rectangular cross-sectional shapes of polyethylene terephthalate (PET) multifilament yarn on the physical and crimp properties of melt-spun and draw-textured yarn with partially oriented yarns (POY) produced by an industrial melt spinning machine and then draw textured yarns (DTY) was produced by an industrial frictional false twist texturizing machine under the same conditions. All yarn samples with two round and rectangular cross-sectional shapes, linear density, thermal shrinkage, degree of crystallinity, and tensile properties (strength, elongation at break, and initial modulus) were analyzed. Also, for DTY yarns, in addition to the mentioned tests, the crimp properties (crimp shrinkage, crimp modulus, and crimp stability), the amount of resiliency, and the ratio of tension after twisting zone to tension before twisting zone (T2/T1) were also investigated. In addition, to know the microstructural condition of fibers, an X-ray diffraction test was performed for textured yarn samples. According to the results, it was found that the difference in tensile properties and thermal shrinkage of POY yarns of both cross-sections is small, despite the statistical significance. However, these variations are greater for two round and rectangular cross-sectional shapes in DTY yarns. In comparing the resiliency values of DTY yarns, the yarn with a rectangular cross-sectional shape showed a higher resiliency value than the round cross-sectional shape. In addition, the crimp properties of DTY yarn with a round cross-sectional shape were better than a rectangular cross-sectional surface, which can be attributed to its higher crystallinity and consequently, softness and texturability compared to a round cross-sectional shape.