Elastic Strain of PTT/PET Self-Crimping Fibers

This paper studies the relationship between crimp curvatures and elastic strains of two series of PTT (Polytrimethylene terephthalate)/ PET (Polyethylene terephthalate) self-crimping fibers produced with two different spinnerets which merge PTT and PET fluids at different points. The crimp curvature is estimated based on fiber crosssectional parameters and the polymer properties. The elastic strain, the strain associated with crimp removal, is measured directly from the stressstrain curves of the fibers. It was found that the crimp curvatures of the PTT/PET filaments in the two series increased with their PTT contents. The elastic strains of the PTT/PET filaments in each series showed a linear positive correlation with the estimated crimp curvatures. A linear equation (R=0.979) was established to predict the elastic stain from the calculated curvature for fibers in different series. This prediction equation can help to determine appropriate fiber cross section, composite ratio and distribution of the two components in the design stage of filament. The paper also shows a color image of dyed PTT/PET filaments, which is helpful in examining the interfacial morphology of the two components. Thus, the spinning method has a certain influence on the interfacial morphology of the fiber cross-section.