부산대학교 도서관

In this study, the effect of drawing conditions of PET/PBT side-by-side bicomponent crimp yarns on the mechanical properties, the crimp contraction, and the elastic strain of the fabrics was investigated. The correlation between the crimp contraction and thermal shrinkage of the bicomponent yarns and the elastic strain of the fabrics was obtained. The specification for the partially oriented PET/PBT bicomponent latent crimp yarns was 80 denier/48 filaments whose intrinsic viscosity for PET and PBT was 0.65 and 0.80, respectively. The PET/PBT bicomponent yarns were further drawn to investigate the effect of drawing conditions. Tensile strength increased and elongation at break decreased with increasing the draw ratio, while the drawing temperature and heat set temperature had little effect.The draw ratio had the greatest effect on crimp contraction, crimp recovery and the elastic strain of the fabrics relative to the drawing temperature and the heat set temperature. As a result of the correlation between the elastic strain of the fabrics which depends on crimp contraction and thermal shrinkage, a negative correlation for thermal shrinkage and a positive correlation for crimp contraction were observed, respectively. The X-ray diffraction analysis confirmed that the crystalline structure of the prepared yarns developed by increasing the draw ratio and heat set temperature. However, it was difficult to separate the contribution of crystal structure development from PET and PBT because the unit cell structure of both PET and PBT crystals was triclinic and hence the crystal peaks of the two polymers were overlapped. In the DSC thermograms of PET/PBT biocomponent fibers, the melting endotherms of each polymer were clearly separated, because the melting temperature of PET and PBT is different. Thus, the heat of fusion of the each component showing the crystallinity of the polymer was obtained. The heat of fusion of the PET and PBT increased with increasing the draw ratio. The increase in the heat of fusion of PET was larger than that of PBT. By drawing, the PET (a low shrinkage component) crystals developed more than the PBT (a high shrinkage component) crystals, resulting in a high crimp contraction at the draw ratio of 1.8. Similar to those observed in XRD and DSC, the effect of the draw ratio had the greatest effect on the sonic velocity indicating the degree of fiber orientation.