Factors affecting crimp configuration of PTT/PET bi-component filaments

In this paper, we explored factors that affect the crimp configuration of polytri-methylene terephthalate (PTT)/polyethylene terephthalate (PET) filaments. We selected three PTT/PET filaments that have approximately identical monofilament fineness but different cross-sectional shapes to study how crimp configuration is influenced by the elastic modulus ratio and differential shrinkage between PTT and PET components. The average elastic modulus ratio was obtained from the stress—strain curves and the cross-sectional measurements of the three PTT/PET filaments. The crimp curvature expressions of the three fibers were used to determine that the differential shrinkage of the two components, which was in the range of 6.8—10.01%. It was found that as the elastic modulus ratio (m) increased, the crimp curvature increases rapidly when the m increases from 0 to 0.5, and then approaches to a stable value when m is larger than 0.5. The crimp curvature increased continuously as the differential shrinkage increased. The crimp curvature of the PTT/PET filament with a dumbbell-shaped cross-section was higher than that of the other two fibers with gourd-shaped and round cross-sections.