ITMA短纤纺纱新技术

介绍了ITMA 2003上展出的纺纱领域的新技术，包括开清棉、梳理工序．以及集聚纺、摩擦纺等非传统纺纱新工艺。     

涡流纺开发新型纱线的趋势及相关技术的探析

目前,涡流纺可开发多种新型纱线：高性能的纤维素纤维纱线、用改性涤纶开发涡流纺新型纱线、包芯纱、色纺纱线、多组分功能性混纺纱、腈纶短纤纯纺与混纺的涡流纺纱线等。要在涡流纺设备上纺好各种新型纱线,应从原料优选、纺纱工艺优化、专件器材的选用和保养及控制好车间温湿度等方面做好工作,并把握好速度、效率、质量三者关系,这是生产出耐磨性好、毛羽少、表面光洁、涡流纱的重要保证。     

气流槽聚纺纱断头理论分析及试验

为解决气流槽聚纺纱纺长纤维时,纱线容易断头的问题,针对气流槽聚纺纱中的前罗拉、前胶辊以及气流槽聚罗拉组成的须条浮游区建立了流体模型,采用Ansys14.0软件中的fluent模块进行浮游区气流模拟,通过改变前胶辊和气流槽聚罗拉的隔距来探究浮游区长度变化对成纱断头、毛羽和断裂强力的影响。结果表明:隔距为1.0 mm时成纱断头最少,3 mm以上毛羽数量最少,成纱断裂强力高。     

生物质纤维/菠萝叶纤维多组分混纺纱线的品质与性能

菠萝叶纤维粗且长,表面有枝节,纵向平直,单独成纱质量较差,为提高其可纺性,结合绢丝、羊毛、壳聚糖纤维、Lyocell纤维和聚乳酸(PLA)纤维的性能特点,选取绢纺系统将菠萝叶纤维分别与这几种纤维混纺制备16.7 tex×2两组分纱线和14.3 tex×2三组分纱线,并测试其力学性能、条干均匀度、毛羽等指标.结果表明:所...     

The effect of blend ratios of unrelaxed and relaxed acrylic fibres on physical properties of high-bulk worsted yarns

Abstract

High-bulk acrylic yarns which contract and increase in bulk during the heat relaxation process are produced by blending two types of fibres with different shrinking power in the spinning process. In this paper, high-bulk acrylic yarns (steamed and dyed) with different shrinkable fibre blending ratios were produced. Experimental results show that by increasing the shrinkable fibre blending ratio up to 40%, the specific volume and shrinkage of both dyed and high-bulk acrylic yarns are steadily increased while their tensile strengths are decreased. Further increasing the shrinkable fibre blending ratio causes the specific volume and tensile strength properties to decreased and increased respectively. However, the yarn shrinkage does not change significantly. It is also found that both dyed and high-bulk acrylic yarns have the highest elongation at 20% shrinkable fibre blending ratio. In general, the specific volume and tensile strength of high-bulk acrylic yarns are more than those of dyed acrylic yarns but their shrinkage and elongation values are similar.     

An investigation on yarn engineering using artificial neural networks

Abstract

Engineering of spun yarns having specific tensile, evenness and hairiness characteristics is a long-cherished dream of spinning technologists. Selection of suitable raw materials at minimum cost and optimisation of process parameters are the two major tasks to be achieved to manufacture engineered yarn. Advent of high-speed fibre-testing machines and development of powerful modelling tools such as artificial neural network (ANN) have provided a great impetus in the yarn engineering research. This article demonstrates the feasibility of yarn engineering by developing a yarn-to-fibre ‘reverse’ model, using ANN. This approach is entirely different from the prevailing forward models, which predict the properties of final yarn using the fibre properties as inputs. The cost minimisation of cotton fibre mix was ensured by using the classical linear programming approach in combination with ANN. The engineered yarns demonstrated good agreement with the target yarn properties.     

扰流空心翅片式微流道液冷板流动换热特性研究

液冷板冷却技术是解决高功率芯片热管理问题最有前途的技术之一,带翅片结构的液冷板具有低流阻、低热阻的优势,因而受到广泛关注。目前翅片结构多以实心为主,空心交错翅片对液冷板散热能力和压降等冷却特性的影响尚未得到系统的研究。对此,设计了空心交错翅片液冷板,采用数值模拟的方法研究进口温度和流量对液冷板流动换热特性的影响。模拟结果表明,空心翅片式液冷板具有良好的散热性能,随着进口温度的升高,液冷板温度不均匀性逐渐降低,但降低趋势有所减缓,而流量的增大对降低平均热阻有显著的作用,当进口流量超过1.2 L/min时,液冷板的平均热阻可低于0.04℃/W;然而,流量的增大也提高了流动阻力,当流量增大至1.7 L/min时,流体出口区域形成涡旋,产生回流区,不利于液冷板的散热效果,且流动阻力增大。     

不同进水流速对泵站进水池漩涡的影响

为探究泵站进水流速大小与泵站进水池水流流态、漩涡的产生与发展变化规律,结合泵站实际运行情况,建立引渠、前池、进水池和进水管的泵站物理模型和湍流数学模型,采用VOF模型和非定常的SST k-ω湍流模型对9种不同流速的泵站进水水流特性进行数值模拟,分析不同进水流速的泵站进水池水流流场分布、漩涡涡量的变化及分布规律。研究结果表明:当进水流速为0.322 2～0.564 2 m/s时,泵站表面漩涡的强度随进水流速的增大而增强:当进水流速为0.322 2～0.401 6 m/s时,进水池出现Ⅲ、Ⅳ型漩涡;当进水流速为0.483 5 m/s时,进水池出现Ⅴ型漩涡;当进水流速为0.520 8～0.564 2 m/s时,进水池出现Ⅵ型漩涡。将数值计算结果与模型试验结果进行对比,两者基本吻合。研究结果可为泵站工程设计提供参考。     

脱油型水力旋流器结构建模及流场分布特征研究

针对所建立的脱油型静态水力旋流器结构设计模型进行了简要的分析。根据旋流器结构特征，确定其相应的结构参数及比例缩放的关系模型，同时对旋流器流场中液流的自由涡、强制涡、组合涡与螺旋涡分布进行了理论分析与计算，对加深人们对旋流分离技术的理解，具有重要的工程实际意义。     

Multifunctional Smart Textronics with Blow‐Spun Nonwoven Fabrics

Here, the fabrication of nonwoven fabric by blow spinning and its application to smart textronics are demonstrated. The blow‐spinning system is composed of two parallel concentric fluid streams: i) a polymer dissolved in a volatile solvent and ii) compressed air flowing around the polymer solution. During the jetting process with pressurized air, the solvent evaporates, which results in the deposition of nanofibers in the direction of gas flow. Poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) dissolved in acetone is blow‐spun onto target substrate. Conductive nonwoven fabric is also fabricated from a blend of single‐walled carbon nanotubes (SWCNTs) and PVdF‐HFP. An all‐fabric capacitive strain sensor is fabricated by vertically stacking the PVdF‐HFP dielectric fabric and the SWCNT/PVdF‐HFP conductive fabric. The resulting sensor shows a high gauge factor of over 130 and excellent mechanical durability. The hierarchical morphology of nanofibers enables the development of superhydrophobic fabric and their electrical and thermal conductivities facilitate the application to a wearable heater and a flexible heat‐dissipation sheet, respectively. Finally, the conductive nonwoven fabric is successfully applied to the detection of various biosignals. The demonstrated facile and cost‐effective fabrication of nonwoven fabric by the blow‐spinning technique provides numerous possibilities for further development of technologies ranging from wearable electronics to textronics.