Abstract:

Objective Bio-based elastic polyester (PTT) fiber is the only biomass elastic staple fiber that can be commercially produced at present in line with the promotion of environmental protection. PTT fiber has a good development prospect, but is unable to spin yarns from pure PTT fibers at this stage. This paper reports a new spinning scheme for producing cotton/PTT fiber blended yarns and reports on the analysis and comparison of the properties of knitted fabrics from this blended yarn.

Method Three different forms of cotton fibers were adopted to assist PTT fibers in the blowing process to form cotton rolls and slivers. Cotton/PTT fiber (60/40) blended yarn with a linear density of 14.7 tex was produced by siro spinning, which was used for producing a weft knitted fabric. The properties of bursting, pilling, abrasion resistance, air permeability, moisture permeability and drape of the fabric were measured and analyzed. Then the fabric properties were comprehensively evaluated by using fuzzy evaluation method. The forms of cotton fibers blended with the PTT fiber were carded sliver, carded net and combed sliver respectively, and the corresponding yarns were named as a, b and c.

Results The longitudinal shape of the PTT fiber is similar to the curl of a spring (Fig.1). The performance parameters of the selected fiber materials were shown that the linear density of cotton fiber was smaller and the average length was shorter than that of the PTT fiber, but the breaking strength and moisture regain are larger (Tab.1). Elongation at break of PTT fiber was high. According to the performance test results of three sets of 14.7 tex cotton/PTT fiber (60/40) blended siro yarns, blended yarns with combed sliver assisted with PTT showed smaller evenness coefficient, less hairiness, and larger breaking strength and elongation(Tab.2). The basic parameters of the Rnitted fabric can be seen that the course and wale densities showed little difference from the uniform set value (Tab.3). By comparing the test data of the Rnitted fabrics, it was concluded that fabric C had higher bursting strength, better anti-pilling effect and better air permeability, and fabric B had good wear resistance, and fabric A illustrated good moisture permeability. The fuzzy comprehensive evaluation model was established to evaluate the fabric comprehensively, and the evaluation function of fabric C was greater than that of fabrics A and B. Fabric C showed high bursting strength and high anti-pilling grade, indicating good durability and breathability of the fabric. The static drape coefficient was found small, suggesting that the fabric had good softness and was suitable for casual wear.

Conclusion The cotton fiber in the blended yarn has a highly straightened, which can increase the friction between the cotton and PTT fibers to improve the bursting property, anti-pilling and air permeability of blended yarn knitted fabric. It is also revealed that the amount of PTT fiber on the surface in the fabric leads to better wear resistance, however the moisture permeability and drapability of the fabrics have little influence on cotton fiber morphology. Based on the fuzzy evaluation model, the combed sliver of cotton fiber is effective to assist the PTT fiber to form a cotton roll, and the comprehensive wearing performance of its blended yarn fabric is better.

Key words: bio-based elastic polyester fiber, cotton fiber, blended yarn, knitted fabric, wearability, siro spinning