Electrochemical hydrogen storage characteristics of nanocrystalline and amorphous Mg_2Ni-type alloys prepared by melt-spinning

The nanocrystalline and amorphous Mg2Ni-type alloys with nominal compositions of Mg2Ni1-xMnx （x=0, 0.1, 0.2, 0.3, 0.4） were synthesized by melt-spinning technique. The spun alloy ribbons with a continuous length, a thickness of about 30 μm and a width of about 25 mm are obtained. The structures of the as-spun alloy ribbons were characterized by XRD and HRTEM. The electrochemical hydrogen storage characteristics of the as-spun alloy ribbons were measured by an automatic galvanostatic system. The electrochemical impedance spectrums （EIS） were plotted by an electrochemical workstation. The hydrogen diffusion coefficients （D） in the alloys were calculated by virtue of potential-step measurement. The results show that all the as-spun （x=0） alloys hold a typical nanocrystalline structure, whereas the as-spun （x=0.4） alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Mn for Ni facilitates the glass formation in the Mg2Ni-type alloy. The substitution of Mn for Ni significantly improves the electrochemical hydrogen storage performances of the alloys, involving the discharge capacity and the electrochemical cycle stability. With an increase in the amount of Mn substitution from 0 to 0.4, the discharge capacity of the as-spun （20 m/s） alloy increases from 96.5 to 265.3 mA·h/g, and its capacity retaining rate （S20） at the 20th cycle increases from 31.3% to 70.2%. Furthermore, the high rate dischargeability （HRD）, electrochemical impedance spectrum and potential-step measurements all indicate that the electrochemical kinetics of the alloy electrodes first increases then decreases with raising the amount of Mn substitution.

Hydriding and dehydriding characteristics of nanocrystalline and amorphous Mg_(20-x)La_xNi_(10)(x=0-6) alloys prepared by melt-spinning

In order to improve the hydrogenation and dehydrogenation performances of the Mg2Ni-type alloys, Mg was partially substituted by La in the alloy, and melt spinning technology was used for the preparation of the Mg20-xLaxNi10 （x=0, 2, 4, 6） hydrogen storage alloys. The structures of the alloys were studied by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and high-resolution transmission electron microscopy （HRTEM）. It was found that no amorphous phase formed in the as-spun La-free alloy, but the as-spun alloys containing La held a major amorphous phase. When La content x≤2, the major phase in the as-cast alloys was Mg2Ni phase, but with further increase of La content, the major phase of the as-cast alloys changed into LaNi5＋LaMg3 phase. Thermal stability of the as-spun alloys was studied by differential scanning calorimetry （DSC）, showing that spinning rate was a negligible factor on the crystallization temperature of the amorphous phase. The hydrogen absorption and desorption kinetics of the as-cast and as-spun alloys were measured using an automatically controlled Sieverts apparatus, confirming that the hydrogen absorption and desorption capacities and kinetics of the as-cast alloys clearly increased with rising La content. For La content x=2, the as-spun alloy displayed optimal hydrogen desorption kinetics at 200 ℃.

STUDIES ON THE CRIMP BEHAVIOR OF SIDE-BY-SIDE BICOMPONENT POLYAMIDE FIBERS

The supermolecular structure and mechanical properties as well as the crimp behavior of theside-by-side polyamide (PA 66-C710) fibers are studied by means of density gradient method,sonic measurement,X-ray,diffractometry,differential scanning calorimetry,crimp tester etc.fortheir as-spun fibers,drawn fibers,and boiling-water treated fibers.The effects of the processingand treatment conditions on the formation of the supermolecular structure and the crimp behaviorof the fibers are investigated and discussed in detail,also the crimp mechanism of the side-by-sidebicomponent fibers is proposed.From these results,it is shown that by adopting suitable spinningfinish,reasonable processing technology and optimal heat treatment conditions the side-by-sidebicomponent polyamide fibers with excellent crimp property,close to that of nylon texturizedstretch yarns,can be obtained.

Geometric shapes of the interface surface of bicomponent flows between two concentric rotating cylinders

In this paper, the shape problem of interface of bicomponent flows between two concentric rotating cylinders is investigated. With tensor analysis, the problem is reduced to an energy functional isoperimetric problem when neglecting the effects of the dissipative energy caused by viscosity. We derive the associated Euler-Lagrangian equation, which is a nonlinear elliptic boundary value problem of the second order. Moreover, by considering the effects of the dissipative energy, we propose another total energy functional to characterize the geometric shape of the interface, and obtain the corresponding Euler-Lagrangian equation, which is also a nonlinear elliptic boundary value problem of the second order. Thus, the problem of the geometric shape is converted into a nonlinear boundary value problem of the second order in both cases.

Studies on Melt Spinning of Sheath-Core Bicomponent Fibers: Fundamental Equations on the Dynamics of Melt Spinning

An attempt was made to numerically compute the temperature profile within the melt spinning of sheath core bicomponent fibers by deriving a set of simultaneous partial differential equations. The effects of acceleration, gravity, and air friction on the kinetics of the polymer were included and the upper-convected Maxwell model as the constitutive equation was adopted in this model.The sheath- core bicomponent fibers were partitioned intb a serial of circular cross section and it is assumed that each circular cross section has a temperature gradient while conducting the equation of energy balance. A mathematical model was developed to describe the melt spinning of sheath-core bicomponent fibers.

Influence of Fiber Properties and Processing Parameters on Properties of Highloft Nonwoven Bonded by Bicomponent Polyester Fibers

Highloft nonwoven was produced by heat bonding of bicomponent polyester fibers. The effect of fiber properties and processing parameters on the mechanical properties of the nonwoven was investigated. The heat bonding processing parameters for the nonwoven were optimized. The results show that the range of processing temperature is wider while the shell melting point of the bicomponent fibers (Tm1) is lower. The best processing temperature is about 15℃ higher than Tm1 while the shell melting point (Tm1) is higher.

Study on the Process Technology of PA6/PET Bicomponent Fiber

PA6/PET bicomponent fiber at different spinning speedswere produced. Influences of cross blowing, spinning speed, PA6 and PET component ratio, drawing condition etc. on the mechanical properties, heat shrinkage,orientation and crystallization of the fiber were investigated. Also the rules among these influencing parameters were obtained. The splitting property of the fiber and its influence on the textile processing are discussed, which offers a base for the production of PA6/PET bicomponent fiber using splitting technology.

INFLUENCE OF POLYMER CHARACTERISTICS AND MELT-SPINNING CONDITIONS ON THE PRODUCTION OF HIGH RANDOMNESS 60PHB/PET THERMOTROPIC LIQUID CRYSTAL COPOLYESTER FIBER

Six samples of linear high randomness 60PHB/ PET thermotropic liquid crystal copolyesters are made by melt copolymerization at 290℃ , whose randomness about 0.955 is measured by the discernible ’H-NMR spectrometer. High tenacity, high module fiber is prepared by melt spinning in liquid crystal phase. The effect of molecular weight, shear rate, temperature as well as spinning drawn ratio on the mechanical behavior of 60PHB / PET copolyester fiber are shown that, lower shear rate (2 10 s-1), higher temperature melting （300℃ ）, lower temperature spinning （280℃ ） and higher molecular weight are favourable to the increase of the fiber mechanical properties. With the variance of drawn ratio, fiber mechanical property has a transition point due to traversion from shear-orientation to drawn-orientation. The copolyester fiber has high crystallinity, high orientation at the crystalline region, high chain orientation and high regular fibrillar structure.

熔纺双组分超细纤维成型工艺及其应用研究进展

熔纺双组分超细纤维由于其原料和成型技术的组合多样性而备受青睐。然而,在现有的制备工艺中,熔纺双组分超细纤维存在如能耗大、难以细旦化和污染环境等问题,限制了其在实际生产和高质应用领域的进一步发展。并且在实际的生产过程中,不同的原料选择、组件使用及工艺调控等因素都对熔纺双组分超细纤维成型效果影响显著。因此,合理调控熔纺双组分超细纤维成型过程中各阶段影响因素对其综合性能进一步提升具有重大意义。为更全面理解熔纺双组分超细纤维的本质,本文以桔瓣型纤维和海岛型纤维为研究基体,探究了熔纺双组分超细纤维的纺丝成型机理及其影响因素;阐述了熔纺双组分超细纤维多样的开纤工艺(机械开纤、化学开纤和热能开纤);归结了熔纺双组分超细纤维在合成革、空气过滤和医疗卫生等材料领域的应用;最后对熔纺双组分超细纤维广阔的发展前景进行了展望。

热黏合聚乙烯/聚丙烯双组分纺黏非织造材料性能及其过滤机制

为研究热黏合加固技术对双组分纺黏非织造材料结构和性能的影响,以聚乙烯(PE)为皮层组分、聚丙烯(PP)为芯层组分,采取热轧和热风2种热黏合方式制备了PE/PP皮芯型双组分纺黏非织造材料,借助扫描电子显微镜、自动滤料测试仪、孔径测试仪、渗水性测定仪等对2种方法制备的纺黏非织造材料的结构和性能进行测试与表征,并对造成过滤性能不同的原因进行理论分析,阐释纤维滤材的过滤机制。结果表明:随着面密度的增加,热轧黏合纺黏非织造材料的平均孔径逐渐减小,耐静水压逐渐增加,其中面密度为80 g/m^(2)时,平均孔径为25.74μm,耐静水压为3.14 kPa;热风黏合纺黏非织造材料在低阻力、高容尘、品质因数方面的表现均优于热轧黏合纺黏非织造材料,其中面密度为80 g/m^(2)时,以质量中值直径为0.26μm的NaCl气溶胶为过滤媒介,在32 L/min的测试流量下,电晕驻极后热风黏合纺黏非织造材料的过滤效率为76.62%,过滤阻力仅为15.85 Pa;纤维过滤材料的孔隙率越大其过滤阻力越小,容尘量越高。

熔融双组分超细纤维成纤技术研究进展

为深入探究熔融双组分复合纤维原纤化的超细纤维成形技术,介绍了共混纺丝和共轭纺丝2种复合纺丝技术及其在生产超细纤维时的原料及工艺,具体阐述了海岛型复合纤维和裂离型复合纤维开纤工艺及特点,分析了聚合物及工艺对复合纤维生产超细纤维的影响。综述了熔融复合纤维原纤化用到的化学溶剂开纤、水溶开纤、机械开纤等开纤技术。概述了用熔融复合纺丝技术生产的超细纤维材料在合成革、过滤与分离、医用防护、卫生健康等领域中的应用,提出了复合纺丝技术生产超细纤维的发展方向,并指出复合纤维有望通过成形技术实现原料多元化、纤维细旦化、材料功能化等方面的不断发展和创新,将推动相关产业朝着更加可持续和环保的方向发展。

Controllable large-scale processing of temperature regulating sheath-core fibers with high-enthalpy for thermal management

Temperature regulating fibers(TRF_(s)) with high enthalpy and high form stability are the key factors for thermal management. However, the enthalpies of most TRFsare not high, and the preparation methods are still at the laboratory scale. It remains a great challenge to use industrial spinning equipment to achieve continuous processing of TRF_(s) with excellent thermal and mechanical properties. Here, polyamide 6(PA6) based TRF_(s) with a sheath-core structure were prepared by bicomponent melt-spinning. The sheath-core TRF(TRF_(sc)) are composed of PA6 as sheath and functional PA6 as core, which are filled with the shape stable phase change materials(ssPCM),dendritic silica@polyethylene glycol(SiO_(2)@PEG). With the aid of the sheath structure, the filling content of SiO_(2)@PEG can reach 30 %, so that the enthalpy of the TRF_(s) can be as high as 21.3 J/g. The ultra-high enthalpy guarantees the temperature regulation ability during the alternating process of cooling and heating. In hot environment, the temperature regulation time is 6.59 min, and the temperature difference is 12.93℃. In addition, the mechanical strength of the prepared TRF_(sc) reaches 2.26 cN/dtex, which can fully meet its application in the field of thermal management textiles and devices to manage the temperature regulation of the human body or precision equipment, etc.

索罗娜双组分面料的染色工艺

索罗娜双组分纤维由索罗娜和PET两根丝组成,熔丝之间有细小的沟壑,呈卷曲形态。优化后的染色工艺为:染色温度130℃、pH 4.0、浴比1∶15、匀染剂1 g/L、保温时间30 min。研究发现,WFN系列分散染料对索罗娜双组分面料具有良好的染色提升性。染色后面料的耐皂洗色牢度和耐摩擦色牢度均在4级以上。

Facile synthesis of a melt-spinnable polyborazine from asymmetric alkylaminoborazine

A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis（methylamino）borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine（PBN）.This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine（TCB） with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.

低熔点聚酯纤维制备及应用发展趋势

介绍了低熔点聚酯纤维的粘合机理及纤维卷曲原理,总结了纤维现有的制备方法及性能特点;简述了低熔点聚酯纤维在服用纺织品、产业用纺织品、非织造布等产品领域中的应用情况;梳理了目前国内低熔点聚酯纤维主要生产厂家及产品特点;最后指出了低熔点聚酯纤维的未来发展方向,即绿色低碳、个性化定制和功能多样化。

不同一次风率下循环流化床流动特性数值模拟

为了研究一二次风配比对循环流化床锅炉冷态流动特性的影响,对三种一次风率(0.46、0.5、0.54)下的循环流化床锅炉物理模型进行数值模拟研究。采用欧拉框架下的双流体(TFM)模型,通过对比炉内颗粒浓度云图、颗粒浓度曲线图和气相轴向速度曲线图,分析炉内颗粒流动形态。数值模拟结果表明:当一次风率增大时,一次风速增大,二次风速降低,炉膛底部入口处颗粒堆积减少,当一次风率为0.46时能够得到一个较好的环核流动形态。因为在炉膛中上部分细颗粒已经得到充分发展,当细颗粒从炉膛出口被夹带到旋风分离器时,分离器内无论浓度场还是速度场,一次风率的改变并未对其造成太大影响。

高平滑特种纸用工业造纸毛毯的研制

采用环形编织的双底网作为骨架材料,将聚酰胺610(PA 610)、聚酰胺1010(PA 1010)和双组分纤维按一定质量比混合均匀后梳理成网,作为造纸毛毯的纤维层,利用双组分纤维内外层熔点差异使之与周围纤维固结,提高造纸毛毯的耐磨程度和使用寿命。采用低定量、并联式双道梳理和多层铺网工艺,确保毛网成网均匀。采用预压、烧毛、助剂处理和低温定型工艺,提高毯面平整度。所制备的造纸毛毯产品表面平整、耐磨性好,适合高平滑特种纸的生产。

Intermolecular through-space charge transfer enabled by bicomponent assembly for ultrasensitive detection of synthetic cannabinoid JWH-018

Launching the intermolecular through-space charge transfer(TSCT)from a bicomponent assembly for photophysical property manipulation is of great significance in fluorescence probe design.Here,we demonstrate the elaborate control of droplet evaporation dynamics for intermolecular TSCT can facilitate the ultrasensitive detection of JWH-018,a representative synthetic cannabinoid.Driven by diverse intermolecular interactions,the probe,and JWH-018 assemble in a closely stacked manner to emit strong fluorescence at 477 nm,ascribing to the intermolecular TSCT at the S2 state.The strategy realizes an ultra-low limit of detection of 11 nmol/mL and great selectivity towards JWH-018.The practicability is further verified by constructing a sensing chip for JWH-018 aerosol detection,which facilitates the on-site drug abuser screening with the naked eye.Moreover,the proposed assembly-enabled TSCT is expected to find a variety of applications for optoelectronic materials design and photophysical mechanism-dominated molecular recognition.

双组分纤维差异对热风非织造布性能影响的研究

文章主要探讨热风非织造布应用于纸尿裤面层材料时,不同线密度、不同亲水性能的双组分纤维对热风非织造布的厚度、强力、柔软度、液体穿透时间、反渗量等性能的影响。结果表明,热风非织造布的性能受纤维差异的影响非常显著。文章通过对9种不同试样的测试数据进行对比分析,期望能够为热风非织造布的生产厂家在产品质量提升和新产品开发等方面提供参考。

双组分橘瓣型纺粘水刺材料的过滤和力学性能

为获得过滤和力学综合性能优异的双组分橘瓣型纺粘水刺材料,采用单因素试验方法研究了纤网面密度对纺粘水刺非织造材料孔径、过滤性能、拉伸性能以及撕裂性能的影响,并对其结构形貌进行观察分析。结果表明：双组分纤维呈中空橘瓣状,纺粘水刺材料表面纤维大部分裂离为超细纤维,中间层纤维基本为完整的中空结构;纺粘水刺材料的平均孔径为7~10μm,且随着纤网面密度的增大而逐渐减小,过滤效率对应提高;纤网面密度对纺粘水刺材料的纵横向拉伸强力、断裂伸长率和撕裂强力影响显著,随着纤网面密度的提高,上述力学性能指标均逐渐增大,但受到铺网加工方式影响,纺粘水刺材料的纵横向力学性能差异仍较大。