普通乳液聚合法制备丙-苯纳米核壳乳液

文中通过预乳化-半连续的加料工艺制备出了以聚丙烯酸丁酯为核,聚苯乙烯-甲基丙烯酸甲酯为壳的丙-苯纳米核壳乳液,分析了这种乳液聚合的方法制备纳米乳液的机理。通过粒度分布仪测定的乳胶粒的粒径分布为93.4 nm～95.6 nm,分布很窄,乳胶粒的平均粒径为94.5 nm;通过透射电境(TEM)对乳液进行观察,所制的丙-苯纳米乳胶粒具有明显的正向核壳结构,实验证明这种核壳结构是稳定的。     

微乳液化学剪裁制备纳米钛酸钡和二氧化钛

以钛酸丁酯、氢氧化钡和正己醇制备凝胶,用吐温-80/正已醇／环己烷／水制成w／O型微乳液在25℃下进行化学剪裁,将前驱物在550℃下煅烧,分别制备出了纳米钛酸钡和纳米二氧化钛．对产物进行X-射线粉末衍射（XRD）、透射电镜（TEM）、红外（IR）和差热（DTA）分析,研究了煅烧温度对BaTi03和Ti02纳米质点粒径和组成的影响．结果表明,最好的煅烧温度是550℃．所得纳米钛酸钡为具有较好晶型的六方晶体,粒径在30～42nm之间,钡钛摩尔比为1：1;纳米二氧化钛为单一的锐钛矿型八面体结构,平均粒径小于50nm．实验表明,通过凝胶．微乳液法合成的纳米物质可以有效地减少团聚,控制微粒的组成和粒径,且操作简单,成本低．     

细乳液聚合法制备聚丙烯酸/聚硅氧烷复合乳液

以聚硅氧烷为助稳定剂，采用细孔液聚合法合成聚丙烯酸／聚硅氧烷复合乳液。研究了乳化剂类型、聚硅氧烷用量、孔液固含量和甲基丙烯酸用量对细乳液聚合动力学和所得乳液性能的影响。研究结果表明：以十二烷基硫酸钠为乳化剂，聚硅氧烷用量为丙烯酸酯单体质量的3．33％～10．0％时，可获得稳定的聚合过程，所得复合乳液的数均粒径在73nm～77nm之间，乳胶膜吸水率低至4．54％～6．75％。透射电镜照片表明，复合乳胶粒内部存在一定程度的微相分离。     

微乳液法制备纳米氧化锆粉体的研究

以可溶性锆盐(ZrOCl2·8H2O)-十六烷基三甲基溴化铵(CTAB)-正丁醇(C4H10O2)-环己烷(C6H12)组成的微乳液体系为基础、氨水作沉淀剂,在微乳区反应,经过洗涤、焙烧等工序,制备得到粒径10～40nm、形貌可控、分散性良好的ZrO2粉体.通过扫描电镜(SEM)、热分析仪(TG-DSC)以及X射线衍射分析对粉体进行表征,得到了晶相随焙烧温度的变化规律,并通过激光粒度仪以及Scherrer公式计算出粉体的粒度,从而得出粉体的粒度随浓度、溶水量以及焙烧温度的变化规律.     

丙烯酸—苯乙烯共聚乳液增稠机理的研究

本文采用自制的丙烯酸-苯乙烯共聚乳液及1~#、2~#增稠剂,进行了增稠乳液的粘度、润湿角、乳胶粒径及动态粘弹谱等的测定。发现丙-苯共聚乳液增稠后的粘接强度(如剪切强度),不仅大于未增稠的共聚乳液,而且也高于纯增稠剂。本文笔者根据自己的实验结果及前人的工作,提出丙-苯共聚乳液加入增稠剂后,经过增稠剂在乳胶粒上的吸附润湿、增稠剂大分子与聚合物胶粒进行IPN(互穿网络)化、增稠新胶拉的稳定化三个阶段,形成了稳定的丙-苯共聚增稠乳液,即提出三阶段增稠机理的意见。     

微波辐射甲基丙烯酸甲酯与丙烯酸丁酯的乳液共聚合

在微波辐射下,进行了甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)的乳液共聚合。用称量法测定反应的转化率,研究反应动力学;用差示扫描量热仪(DSC)对共聚产物进行了玻璃化温度(Tg)的测试,并通过Tg计算了共聚物中MMA、BA的质量分数;采用透射电子显微镜(TEM)、激光光散射粒度仪(PCS)表征了乳胶粒形态、粒径大小及分布。结果表明,微波辐射乳液共聚合的诱导期短、反应速率快、转化率高;共聚产物只有一个Tg,并随MMA/BA质量配比的减小,Tg从91.4℃降低到-35.4℃;制得粒径小于100 nm的单分散乳胶粒;随着乳化剂浓度增大,乳胶粒水合粒径从194 nm减小到60 nm左右。     

Winsor-Ⅰ型多相微乳液中苯乙烯聚合

在烷基葡萄糖苷(APG)/苯乙烯/水三元体系形成的Winsor-Ⅰ型多相微乳液介质中,通过聚合制得了粒径在35～40nm的单分散聚苯乙烯小球,研究了温度、引发剂类型、引发剂浓度以及单体浓度对产物粒径和分子量的影响.结果表明温度在60～70℃,K2S2O8为引发剂的条件下单分散聚苯乙烯颗粒具有较小粒径(35～40nm),引发剂和单体浓度对粒径的影响很小.     

反相微乳液法制备纳米羟基磷灰石及其表征

采用水溶液(W)/环己烷(O)/Triton X-100(S)/正戊醇(A)反相微乳液体系制备出粒径为20～60nm的球状羟基磷灰石(Hap)颗粒,并用TEM、XRD、IR和动态激光散射等手段对合成的样品进行形貌和结构表征.研究结果表明,合成的Hap具有弱结晶性,与人骨结构较相似.改变水油比可实现对纳米Hap颗粒尺寸的控制.微乳液经超声处理后,可制得尺寸为80nm×(5～15)nm的Hap纳米针状晶体.增加Hap微乳液的搅拌时间对纳米Hap的颗粒度、粒度分布影响不大.     

利用反相微乳液法制备纳米铜粒子

通过反相微乳液法制备了纳米铜粒子,并用透射电子显微镜(TEM)、电子衍射(SAED)和能谱对铜纳米粒子的形貌和物相进行了表征.在H2O/表面活性剂油酸钠摩尔比(W/O)为11、8时分别制得了粒径为50nm、10nm的铜粒子.结果表明:W/O值对纳米铜粒子的粒径有非常明显的影响,当其值由11降到8时,粒径则从50nm降到了10nm,且更加均匀.探讨了水与表面活性剂的摩尔比对制备的纳米铜颗粒的粒径的影响.     

微乳液法制备纳米二氧化硅

研究了在TritoX-10-正辛醇-环己烷-氨水所组成的微乳液体系下,制备纳米二氧化硅的实验方法.并对制备的纳米二氧化硅形貌进行透射电镜分析,结果显示,制备的纳米二氧化硅为均匀球形颗粒,粒径80nm左右.     

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.     

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...     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.