聚乙烯醇/海藻酸钠复合纳米纤维膜的制备和交联改性

采用静电纺丝技术制备聚乙烯醇/海藻酸钠复合纳米纤维膜,利用氯化钙乙醇溶液进行交联改性。研究复合纳米纤维制备、交联工艺对材料表面形貌、耐水性、热性能等的影响。结果表明:纳米纤维直径在200~500nm之间,纤维平均直径随海藻酸钠含量的增大而增大,复合纳米纤维结晶度随海藻酸钠含量的增大而降低,热稳定性随海藻酸钠含量的增大而下降。交联改性后复合纳米纤维材料耐水性提高,纤维形貌保持,纤维之间粘结增多,材料不发生熔融相转变,热稳定性下降。     

钛酸丁酯溶胶-凝胶法交联改性聚乙烯醇纳米纤维膜的研究

采用静电纺丝技术制备聚乙烯醇纳米纤维膜,结合溶胶-凝胶法制备二氧化钛对纳米纤维膜进行交联改性。分析交联前后材料表面形貌、表面化学基团变化以及耐水性和热性能。研究纳米纤维膜对模型污染物罗丹明B的吸附和光催化降解性能。结果表明:交联改性后材料耐水性显著提高,纤维形貌保持不变,材料表面化学基团无显著变化,材料热分解温度提高。交联改性后的纳米纤维膜材料容易吸附罗丹明B,紫外光照射下材料具有一定的光催化降解性能。     

聚乙烯醇/海藻酸钠/甲基丙烯酸缩水甘油酯复合纳米纤维制备与性能

采用静电纺丝技术制备聚乙烯醇/海藻酸钠/甲基丙烯酸缩水甘油酯复合纳米纤维膜,经过加热处理获得交联的海藻酸钠复合纳米纤维膜。研究复合纳米纤维制备、交联工艺对材料表面形貌、耐水性、热性能等影响。结果表明:纳米纤维直径在200～500nm之间,经过120℃热处理后纤维形态不发生改变。热处理后材料发生交联反应,热稳定性提高。改性后的复合纳米纤维材料耐水性随着甲基丙烯酸缩水甘油酯含量增大而提高,吸液倍率在9.6～14.6之间且随着甲基丙烯酸缩水甘油酯含量增大而先增后减,获得的复合纳米纤维膜具有良好的吸液性,有望作为新型医用创伤敷料使用。     

聚乙烯醇/氧化淀粉/二氧化钛复合纳米纤维膜的制备

采用静电纺丝技术制备聚乙烯醇/氧化淀粉/二氧化钛复合纳米纤维膜。采用场发射扫描电子显微镜、差示扫描量热仪及热重分析仪研究组分对材料表面形貌、纤维直径、结晶度和热性能的影响。结果表明,复合纳米纤维表面粗糙程度随二氧化钛含量增加而增大,纤维平均直径在183~222 nm之间且随氧化淀粉含量增加而减小,材料结晶度在30.73%~16.78%之间且随氧化淀粉含量增加而下降,热稳定性随氧化淀粉含量增加而增强。     

用于合成纳米苯丙乳液的纳米TiO2表面改性及表征

研究了利用硅烷偶联剂改性纳米TiO2的方法,并通过FTIR、TEM等手段表征化学改性产物的结构和改性后纳米二氧化钛的分散性,结果表明偶联剂与二氧化钛表面发生化学偶联反应,使二氧化钛表面被偶联剂包覆,从而使二氧化钛改性产物在有机物中具有良好的分散性能.通过TEM分析用改性后的纳米TiO2原位合成的纳米TiO2/苯丙乳液复合体系具有以纳米TiO2粒子为核,以聚合物为壳的核壳结构,该乳液涂膜的耐水性达120h不泛白,硬度为H级,明显优于非纳米苯丙乳液,且具有很好的抑菌作用,可用于制备纳米水性涂料.     

交联改性对静电纺乌拉草提取液/聚乙烯醇纳米纤维膜性能的影响

为了优化用于医用敷料的乌拉草提取液/聚乙烯醇纳米纤维膜的耐水性,对制备好的纤维膜进行气相交联改性.选用戊二醛和浓盐酸作为交联剂和催化剂,在满足医用敷料性能的基础上提高膜的耐水性,进而提高抗菌性,并研究交联时间对膜的影响,确定最优交联时间.采用扫描电子显微镜、电子单纤强力仪及红外光谱仪对改性前后膜的微观形貌、力学性能及分...     

PDDA／Au NPs复合分子沉积膜的制备、表征和摩擦学行为

采用小分子柠檬酸钠对金纳米粒子进行包覆改性,紫外光谱分析经改性的金纳米粒子表面共振吸收峰为526iun,激光纳米粒度仪分析表明其平均粒径为8．4nm．改性后的金纳米粒子通过分子沉积技术,与聚二烯丙基二甲基胺盐酸盐（PDDA）组装,制得单层和多层PDDA／Au NPs复合纳米粒子分子沉积（MD）膜（简称PDDA／Au NPs复合MD膜）．采用原子力显微镜（AFM）研究了PDDA／Au NPs复合MD膜的表面形貌以及摩擦、磨损行为．研究结果表明：该复合膜能降低基底的摩擦力,其中以3层膜降低摩擦力的效果最显著．在氮化硅探针扫描行程达到30次后,膜表面才开始出现磨损痕迹．随着扫描次数的增多,膜表面在探针剪切力的作用下逐渐由致密变得疏松,形成颗粒堆积,使表面粗糙度增大,摩擦力、磨损深度也随之增加．通过实验还发现这种复合膜存在两种非正常磨损现象,即磨损负增长和膜的脱落现象.     

氨基化PAN@SiO2纳米纤维膜除铬性能研究

结合静电纺丝技术和溶胶-凝胶法制备了聚丙烯腈(PAN)@SiO_2纳米纤维膜,利用γ-氨丙基三乙氧基硅烷(KH550)对PAN@SiO_2纳米纤维膜进行氨基改性,成功制备出APAN@SiO_2复合纳米纤维膜。通过扫描电子显微镜、傅里叶变换红外光谱等方法对纳米纤维膜的形貌、结构进行分析,利用电感耦合等离子体原子发射光谱仪对纤维膜的除Cr(Ⅵ)能力进行表征。结果表明:纳米SiO_2颗粒在PAN纳米纤维膜表面生长后,使得PAN纳米纤维膜的比表面积从8.76m~2/g增大到13.32m~2/g;APAN@SiO_2复合纳米纤维膜的机械性能优异;在Cr(Ⅵ)溶液初始质量浓度为100mg/L、SiO_2溶胶-凝胶时间为6h、KH550体积分数为2%条件下,APAN@SiO_2复合纳米纤维膜除铬效果最好,最大吸附量达到112.6mg/g。吸附过程符合准二级动力学方程和Langmuir等温吸附模型。循环吸附实验表明,APAN@SiO_2复合纳米纤维膜经过4次循环实验后,除铬效率依然保持在50%以上。     

静电纺PVDF/O-MMT膜对水面浮油吸附性能研究

采用静电纺丝法制备了添加不同比例[1%(wt,质量分数,下同),2%,3%]的有机改性蒙脱土(O-MMT)聚偏氟乙烯(PVDF)复合纳米纤维膜。利用扫描电子显微镜(SEM)研究O-MMT的添加比例对所制备的复合纳米纤维形貌结构的影响;借助傅里叶变换红外光谱(FT-IR)分析了PVDF及PVDF/O-MMT复合纳米纤维膜的化学结构;并应用DCAT21表面张力仪对比分析了PVDF及PVDF/O-MMT复合纳米纤维膜的吸油速率、单位面积吸油量。结果表明:加入O-MMT后,复合纳米纤维表面变得粗糙且珠节增加;复合纳米纤维膜的疏水性提高,并且纤维膜的单位面积吸油量和吸油速率提高。     

静电纺纳米纤维膜处理重金属离子污水研究进展

静电纺纳米纤维膜具有比表面积大、孔隙率高、易于分离、可重复利用性能好等优点,可有效克服传统重金属污水处理方法的缺点。主要从功能纳米纤维膜、表面改性纳米纤维膜和复合纳米纤维膜三个方面对静电纺纳米纤维膜在重金属污水处理领域的应用加以归纳总结,对不同纳米纤维膜的制备工艺、改性方法、吸附特点及性能等方面进行了对比分析。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...