Study On Structure And Properties Of Side-By-Side Bicomponent Fiber

COPET/PTT side-by-side bicomponent fiber is a new kind of crimped-elastic fibers with chlorine bleaching resistance, chemical resistance and so on. A three-dimensional structure of the coil, good crimped-elasticity and atmospheric dyeability fiber was prepared using COPET self-synthesed and PTT through the composite spinning, forming an independent patented technology.In the paper, the cross-section,the distribution of two sides and the crimp shape of the bicomponent fiber were investigated. The sonic orientation,Differential Scanning Calorimetry (DSC) and Wide Angle X-ray Diffraction(WAXD)were used to research the superstructure of the single component fiber and the bicomponent fiber. The orientation and the crystalline structure in different heat-setting process were also studied. The knitting fabrics and woven fabrics were made .The tensile properties and the elastic-recovery properties were obtained by HD026 fabric tensile machine and KES system.The spinning conditions and the draw-setting temperatures have great influences on structure and properties. The compatibility of the two components is the main factor of preparing the side-by-side bicomponent fiber. The spinning temperature influences the cross-section of fiber.When the COPET spinning temperature is 270℃,the PTT spinning temperature is 253℃,the cross-section of side-by-side bicomponent fiber is peanut shape. Comparing with the single component and bicomponent fibers's superstructure found that the crystal structure of PTT component is compacted, and the crystallinity is greater than COPET component, but the orientation of COPET is greater than PTT. The X-ray diffraction graph of COPET/PTT bicomponent fiber is the combination of PTT diffraction and COPET diffraction, no new diffraction peak appears.When the draw temperature in 70-75℃, the heat-set temperature in 130-150℃, COPET/PTT bicomponent fiber have the great potential crimp prosperities. The composition ratio also influences greatly the crimp properties,the composition ratio of 50/50 has better potential crimp properties for COPET/PTT bicomponent fiber.The heat-set temperature,time,tension,medium and the way influence the crimp propertities of COPET/PTT bicomponent fiber. Temperature is the main factor, whatever of wet-heat or heat-setting, the disorinentation will be accelerated with increasing the temperature;When the heat-setting time is 5-15min, the potential crimp propertities will appear completely. With different heat-setting medium, the influences on crimp propertities is different, the fiber in boiling water will have good crimp propertities. In heat processing, appropriate load will be helpful to improve the crimp elastic-recovery property. When the bicomponent fiber were heat-treated in low draw ratio, the crimp elastic recovery is great, above 80%.The crimp structure and morphology was also investigated. The result shows that the COPET/PTT bicomponent is helical structure, the COPET component is inside of the helix, the PTT component is outside of the helix; In different heat-set conditions, the number of crimp is different, and the results are accordance with the quantitive analysis.The heat-shrinkage and stretch-recovery properties of knitting fabrics and the woven fabrics were studied. The weave structures and area density of the knits influence the stretch-recovery property. The stretch-recovery of the knits is almost above 60%, the highest reached 90%. The heat setting will improve the stretch-recovery property. For woven fabrics, twill weave fabrics have better elasticity and the fabrics contain spandex core-spun yarns have better elasticity than COPET/PTT fabrics.