改性聚乙烯醇偏光膜的制备及性能研究

以聚乙烯醇（PVA）为原料，制备了改性的PVA含碘（mPVA-I）和PVA含双向色性染料（mPVA-D）两类偏光膜，前者的偏光性能明显优于后者。mPVA-I偏光膜较国内商品PVA含磺偏光膜（CPVA-1)有明显的优点，在偏光性能相近的条件下，抗温、抗热性能好，用光电子能谱对膜表层测试表明，B，Co,Ni浓度是影响其性能的原因。     

PTFE/CaCO3杂化中空纤维膜制备及其界面孔研究

以聚乙烯醇(PVA)和硼酸(H3 BO3)的凝胶体为纺丝载体,由聚四氟乙烯(PTFE)分散乳液通过凝胶纺丝法制备PTFE/PVA初生中空纤维,经烧结去除载体,得到聚四氟乙烯中空纤维膜.通过在成膜体系中引入纳米无机粒子碳酸钙(CaCO3),经后拉伸得到具有界面微孔结构的PTFE/CaCO3杂化中空纤维膜.研究了PVA和H3 BO3的络合机理,并讨论了CaCO3对杂化中空纤维膜性能及结构的影响.通过对膜的表面形貌观察表明所得PTFE中空纤维膜是一种均质膜,形成的界面微孔结构不同于PTFE双向拉伸产生的纤维-结点状裂隙孔结构,界面微孔的数量和孔径随着后拉伸倍数的增加呈增大的趋势.     

PVA-AA-KOH-H_2O碱性聚合物电解质的制备与性能研究

采用溶解-铸膜法,制备了聚乙烯醇(PVA)-丙烯酸(AA)-KOH-H2O碱性聚合物电解质膜。为优化电解质膜的性能,研究了成分对电解质膜特性的影响。通过XRD进行物相分析;通过DSC分析了膜的热学特性;通过电化学测试方法测定膜的电导率和电化学稳定窗口。研究显示AA共混可明显改善PVA基碱性聚合物电解质膜的保湿性能和机械性能。KOH和AA可使PVA的结晶度和熔点降低,有利于提高电导率。实验制备的聚合物电解质膜的电导率均可达到10-2S/cm数量级,最大可达0.18S/cm。电导率随膜内KOH、AA、H2O的含量增加而增大;在25～80℃范围内,电导率与温度的关系符合Arrhenius方程,并具有良好的电化学稳定性,电化学稳定窗口达3.6V,可满足大多数器件对电解质的要求。     

聚乙烯醇/钴盐共混膜结构及其对环己烯-环己烷吸附性能研究

采用PVA分别与硝酸钴(Co(NO3)2)、氯化钴(CoCl2)和醋酸钴(Co(CH3COO)2)共混制成均相膜．X-射线衍射研究表明：Co(NO3)2,CoCl2和Co(CH3COO)2能很好地溶于PVA中,且PVA膜中引入钴盐后,结晶度明显下降．通过对环己烯、环己烷溶胀实验发现,3种膜均对环己烯优先吸附,其中PVA／Co(CH3COO)2膜对环己烯优先吸附性能最好,而且环己烯在膜中的扩散也最快达到平衡．     

分离有机/有机混合物的PVA、CA系列膜及其渗透汽化性能研究(Ⅱ) 成膜条件对渗透汽化性能的影响

用溶剂完全蒸发法制备了PVA复合膜 .经对MTBE/MeOH混合物的分离实验得到了PVA复合膜的最佳成膜条件 ,即 :铸膜液中PVA、马来酸浓度分别为 7%、3% ,热处理温度130～ 15 0℃ .在 1%～ 2 %丙酮水溶液中浸泡处理 4～ 8h ,CTA中空纤维RO膜被改性成渗透汽化膜 .CTA中空纤维膜的分离性能优于其它醋酸纤维素系列膜 ,PVA/CA复合膜的性能优于PVA/PAN复合膜和CA/PAN复合膜     

聚乙烯醇(PVA)偏光膜的制备及性能研究

本文采用流延法制备出聚乙烯醇偏光膜,并用紫外可见分光光度仪分别对含碘及含碘、镍、钴的2种偏光膜的光学性能进行了研究。结果表明,偏光膜中加入镍、钴后,偏光膜的单片透光率增加,单片偏光系数及组合偏光率增加;垂直组合时,泄漏光的波峰值左移。     

Co对Ti45Al-8Nb-0.3Y合金组织结构和高温抗氧化性能的影响EI北大核心CSCD

采用真空电弧非自耗熔炼方法制备Ti45Al-8Nb-0.3Y-m Co(m=0,0.5,1,2,原子分数/%,下同)合金,研究合金的组织和高温抗氧化性能。结果表明:Co能够明显细化TiAl-Nb合金组织,但对合金中α_(2)+γ片层组织的形成具有较强烈的抑制作用,并且会促进富Co的B_(2)相析出。Ti45Al-8Nb-0.3Y-mCo合金在1000℃空气中氧化100 h后形成的氧化膜均主要由较为疏松的TiO_(2)和Al_(2)O_(3)混合组成,且TiAl-Nb-0.3Y合金的氧化增重随Co含量增加而增大,但氧化膜的抗剥落能力随Co含量增加而明显提高;添加Co能够在一定程度上降低氧化膜的内应力,对提高其抗剥落性能有益,但引起的粗大B_(2)相析出削弱了合金的高温抗氧化性能。     

聚氨酯／环氧树脂互穿网络二阶非线性光学材料

制备了一类新型的各含对硝基苯偶氮苯胺发色团的聚氨酯和环氧树脂的互穿网络型二阶非线性光学聚合物。用程序升温及升压电晕极化法可制得有良好光学质量的极化膜。ＤＳＣ曲线显示该互穿网络聚合物有１个玻璃化转变温度。在一维刚性取向气体模型的基础上，通过可见吸收光谱研究了该极化膜的非线性光学性质。其二阶非线性光学极化系数可达１０＾－７ｅｓｕ量级，发色团有优异的取向稳定性，其序参数在１００℃仍可长期稳定。     

聚乙烯醇改性对原子层沉积氧化铝复合隔膜的影响

原子层沉积技术(ALD)是一种具有表面自限性反应的薄膜生长技术,可以精准控制薄膜的生长。本文研究了ALD技术包覆聚烯烃隔膜,制作纳米氧化铝聚烯烃复合隔膜。聚烯烃膜表面无ALD氧化铝反应基团,造成ALD氧化铝生长成核慢,前期反应效率低,最终生长的氧化铝多形成团簇而非完整覆盖的薄膜。为了增强ALD氧化铝包覆聚乙烯膜(PE)的全覆盖薄膜生长,将PE膜进行了聚乙烯醇(PVA)表面改性处理,然后进行ALD Al_2O_3生长。通过扫描电镜、红外光谱、电感耦合发射光谱仪等技术手段系统分析了PVA表面改性对ALD Al_2O_3包覆PE膜性能指标的影响。结果表明,PVA改性可以简单有效地在PE膜上增加羟基(-OH)作为ALD反应位点。处理后的PE膜进行ALD Al_2O_3生长,前驱体进入反应腔室后更易与表面羟基进行反应,提高表面生长效率,纤维上均匀包覆氧化铝,无岛状生长的Al_2O_3团簇。同时PVA改性可以增强复合膜的耐热收缩性能,减少厚度增加,减轻机械结构的损坏。     

不同聚乙烯醇偏光基膜的结构与性能

研究比较了3种不同聚乙烯醇(PVA)偏光基膜制品的结构和性能差异。通过对样品进行的核磁共振、红外光谱、结晶性能、力学性能、光学性能等测试,结果发现3种样品主要成分一致,PVA原料的立体结构比例有所不同;间规度较高,无规立构含量较小的Kurary样品的偏光性质最好,偏光度在95%以上;Kurary的样品结晶宽度最小,PVA原料结构较均匀;皖维的样品结晶宽度最大,熔点最高。50 mm/min速度下,Kurary的样品拉伸断裂应力强于台湾长春和皖维的样品。     

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.……     

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...     

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.     

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 ...