关键词: 热塑性聚酰胺弹性体, 弹性回复率, 结晶, 取向, 热收缩

Abstract: With the improvement of people's living standards, consumer's demand for textile function has shifted from warmth and beauty to more details such as comfort and appropriateness. Among them, elastic clothing has been favored by many consumers due to its shaping and comfort properties. Elastic fibers are synthetic fibers with low modulus, high elongation, and high elastic recovery, and can be divided into intrinsic elastic fibers and form elastic fibers according to their elastic mechanisms. Intrinsic elastic fibers mainly include polyurethane elastic fibers, polyester elastic fibers, and polyolefin elastic fibers. Among them, polyurethane elastic fibers are widely welcomed due to their excellent performance, but they cannot be used as bare yarns and are often used in the form of wrapped yarns with other fibers; form elastic fibers such as bicomponent composite crimped fibers have good elastic recovery rate under small forces, but lack intrinsic elasticity after crimping is eliminated. 
Thermoplastic polyamide elastomer (TPAE), a new type of thermoplastic elastomer, is composed of polyamide hard segments and aliphatic polyester or polyether soft segments. Due to the thermodynamic incompatibility between the soft and hard chain segments of TPAE, a microphase separation structure is produced. The hard chain segment of TPAE is rich in crystalline microregions and hydrogen bonds, and its type determines the mechanical properties such as hardness, wear resistance, and chemical resistance of TPAE; the soft segment is located in the amorphous region, and its type determines its low-temperature mechanical properties, flexibility, and elongation. Therefore, the content ratio of soft and hard chain segments and the degree of polymerization have  decisive influence on the physical properties of TPAE. Compared with TPU with excellent elastic recovery rates, TPAE has better thermal stability, with a maximum operating temperature of 175℃ and can be used for a long time at 150℃. Therefore, TPAE is widely used in sports, aerospace, medicine and other fields, but there are fewer research reports on fibers. In order to expand the application of TPAE in the field of elastic fibers, we used TPAE as raw material and prepared TPAE primary silk by using a laboratory horizontal micro extruder, and then subjected it to different stretching multiples and thermal setting temperatures for post-processing. We investigated the effects of stretching multiples and thermal setting temperatures on fibers crystalline orientation, elastic recovery rates, creep resistance, and thermal shrinkage properties. The results show that the stretching and thermal setting process can make the TPAE fibers structure more complete. When the thermal setting temperature is 100℃ and the stretching multiple increases from 2 to 5 times, the elastic recovery rate increases from 91.1% to 94.0% at a fixed extension of 15%, and from 87.2% to 90.7% at a fixed extension of 50%. When the stretching multiple is 4 times, the elastic recovery rate increases from 87.0% to 91.5% as the thermal setting temperature increases from 80℃ to 120℃ at a fixed extension of 15%, and from 88.7% to 90.7% at a fixed extension of 50%, indicating excellent elastic recovery performance. 
Based on the test results of the properties of TPAE fibers in this paper, they can be used in different elastic fabrics can be developed to expand their application in the field of fibers.

Key words: thermoplastic polyamide elastomer, elastic recovery rate, crystalline, orientation, thermal shrinkage