Abstract With the spectacular physical properties of electrical conductivity, mechanical strength and thermal conductivity, carbon nanotube (CNT) fibers are favored in many fields such as energy storage devices, sensing, electromagnetic shielding and structural reinforcement, especially in flexible sensing devices. However, the lower tensile properties of CNT fibers limit their further application in stretchable strain sensors, especially when monitoring large deformation variables. Here, large-scale continuous production of CNT fibers has achieved through floating catalytic chemical vapor deposition (FCCVD) technology. In the meantime, the CNT fibers were hybrid with Kevlar fibers to obtain hybrid CNT yarns with the strength of 168.4 MPa and the electrical conductivity of 7.78 × 10 4 S m −1 . The strength of the hybrid CNT yarns produced by this method is higher than that of 40 count cotton yarns, which is perfectly suited for the fabrication of textile devices. Through knitting with three-dimensional elastic fabrics, the textile-based sensors exhibit promising sensing ability, washability, weather tolerance and sweat resistance, owing to the excellent physical and chemical properties of the hybrid CNT yarns. Moreover, stretchable strain sensors exhibit fast response and cycle stability, which provides unique opportunities in designing smart textiles with fast response and environmental durability.
Swirl nozzle spinning is an effective method to reduce ring-spun yarn hairiness due to device structure and vortex characteristics. This study establishes a computational domain of a swirl nozzle comprising an air inlet channel and a yarn channel to investigate the characteristics of the vortex in the swirl nozzle and the effects of inlet pressure on the wrapped force of the yarn. Simulation results show that the airflow rotates clockwise toward the two yarn entrance directions; moreover, the pressure at the central area of the yarn channel is lower than that of the surrounding area, which is good for the yarn’s steady movement and free fibers wrapping on the yarn surface into the yarn body. When the inlet pressure is high, the pressure spreading to each section of the yarn channel is also high. When the difference between the pressure near the inner wall and the yarn axis is high, the yarn surface has added high pressure, and the velocity and its fluctuation are also high. Experiment result reveals that 0.2 MPa is sufficient in significantly reducing yarn hairiness and that operating the nozzle under a low air pressure is economical. Thus, the numerical simulation can provide the theoretical as well as quantitative reference for the vortex tube design in the coming future.
This goal of this paper was to determine the flow characteristics of compressible airflow in the yarn duct of an interlacer using numerical simulations to study the effects of cross-sectional shapes of yarn duct on the performance of interlacers. A CFD (Computational Fluid Dynamics) software package ANSYS CFX was used to calculate the flow patterns in the yarn duct. The relationship between the performance of the interlacer and the distribution of the velocity vector, the airflow speed and the particle trace of flow were examined in order to propose a better design of interlacers. From the results of the calculations, if the vortices on the middle cross-section of the yarn duct make the filaments revolve continuously, then a large number of entanglements can be achieved. The velocity at the central point of the yarn duct was the deciding factor as to a sufficient opening for the filaments. However, too high of a velocity makes the filaments stay on the wall, hindering them from entangling with each other.
Abstract Interlacer is the key part of interlacing technology that is adopted to improve the cohesion between loose multifilaments. Aimed at finding the interlacers with better performance, the present research designed five interlacers that can be classified into round type and cornered type. These five interlacers are different in cross-sectional shapes of yarn channel but are the same in the cross-sectional area. The evaluation of the performance of the interlacer includes the number and the strength of the tangles of the interlaced yarn it produces. Experiments are carried out at various supplied air pressures, yarn speeds and feed ratios. It was found that the interlacer with round cross-sectional shape of yarn channel is capable of producing an interlaced yarn with a large number of tangles and the cornered cross-sectional shape is effective in improving the strength of tangles. Among these five interlacers, the interlacer with an elliptical or an inverse-triangular shape has the best processing performance
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