聚苯胺@季铵盐阳离子改性粉煤灰漂珠的制备与电流变性能

选用3种不同链长的烷基季铵盐阳离子表面活性剂即十二烷基三甲基溴化铵（DTAB）、十四烷基三甲基溴化铵（TTAB）和十六烷基三甲基溴化铵（CTAB）对粉煤灰漂珠（FAFB）进行改性,并将改性产物与苯胺（An）共混进行乳液聚合,制备聚苯胺@有机改性粉煤灰漂珠（PAn@OFAFB）复合材料。采用化学元素分析、FTIR、XRD、SEM、TGA、数字四探针测试仪、LCR数字电桥和旋转流变仪对复合材料进行结构表征以及电流变性能分析。结果表明:改性剂的碳链长度越长,改性效果越好,CTAB吸附在FAFB表面的量最多,且表面吸附率为1.91wt%,PAn和OFAFB 复合程度越明显,FAFB表面包覆的PAn越多;聚苯胺@十六烷基三甲基溴化铵改性粉煤灰漂珠（PAn@FAFB-CTAB）的电导率最大为0.06 S·cm-1;将其作分散相制成的电流变液比PAn-十二烷基苯磺酸（PAn-DBSA）具有更好的电流变效应,抗击穿能力较纯PAn提高了0.5 kV/mm;将FAFB作为PAn的载体能够提高复合材料的悬浮稳定性;引入FAFB-CTAB可以显著改善复合材料的热稳定性,且PAn的相对包覆量为28.07wt%。      

粉煤灰漂珠@BaTiO_3@PAn的制备及其电流变性能

聚苯胺(PAn)作为电流变材料具有响应快、屈服应力大的特点,但因其良好的导电性能导致漏电击穿现象发生,为了进一步增加PAn的悬浮稳定性,引入了粉煤灰漂珠(FAFB),BaTiO_3作为经典的电介质材料也引入其中以进一步提高材料的介电性能。采用逐层包覆的思路,利用溶胶-凝胶法在漂珠表面包覆BaTiO_3,获得FAFB@BaTiO_3,再利用原位聚合法制备以FAFB@BaTiO_3为核、PAn为壳的结构复合材料即FAFB@BaTiO_3@PAn。利用FTIR、XRD和SEM对材料的结构与形貌进行分析,借助四探针技术和LCR数字电桥对材料的导电与介电性能进行分析,利用自组装电流变仪进行了电流变特性测试,考察了7d内的悬浮稳定性能。结果表明:BaTiO_3、PAn确实发生了逐层包覆,且电导率、介电常数、介电损耗和剪切应力均符合复合效应规律,介于PAn与FAFB@BaTiO_3之间,其中,剪切应力可达675Pa(电场强度为3.0kV/mm);漏电现象得到缓解,击穿电压提高了20%;比较悬浮稳定性发现,7d后FAFB@BaTiO_3@PAn悬浮率仍为82%。     

乳液聚合法制备有机改性高岭土/聚苯胺复合材料及其性能研究

以十六烷基三甲基溴化铵为有机化改性试剂,对高岭土进行改性,再以苯胺为单体,十二烷基苯磺酸为掺杂剂与乳化剂,过硫酸铵为引发剂,采用乳液聚合法制备有机改性高岭土/聚苯胺复合材料。结果表明,利用四探针技术测试发现,随着有机改性高岭土掺量的增加,复合材料电导率逐渐下降;FT-IR分析证明采用乳液聚合法可实现高岭土有机化改性及其与聚苯胺原位复合;TGA分析结果表明,复合材料耐热性能随改性高岭土引入量的增加而逐渐增强,当掺量为50%(质量分数)时,聚苯胺的分解起始温度和失重最快温度分别提高了13℃和36℃;采用SEM分析证明二者复合成功;XRD分析说明改性高岭土与聚苯胺的复合仅通过物理吸附作用而未发生插层。     

聚苯胺@粉煤灰漂珠复合材料的导电及介电性能

为获得具有良好电流变性能的分散相粒子,利用γ-氨基丙基三乙氧基硅烷(APTES)修饰粉煤灰漂珠(FAFB),将聚苯胺(PAn)以化学键的方式偶联在修饰后的FAFB(mod-FAFB)表面,形成以mod-FAFB为核、PAn为壳的核-壳结构复合材料。采用FTIR、SEM、数字式四探针以及LCR介电谱仪对PAn@mod-FAFB复合材料的结构与性能进行分析,讨论了不同mod-FAFB含量对PAn@mod-FAFB复合材料导电性能及介电性能的影响。结果表明:以化学键接枝聚合的PAn@mod-FAFB核-壳结构复合材料电导率相对较高,且随mod-FAFB含量的增加而减小;在较低交变电场频率(100~2 000kHz)下其相对介电常数较大,且随mod-FAFB含量的增多,PAn@mod-FAFB复合材料的介电常数明显减小;PAn@mod-FAFB复合材料的介电损耗相对较小,随mod-FAFB含量的增多而急剧减小。     

聚苯胺包覆镍纤维的制备及电性能研究

镍纤维经预处理后,采用化学氧化法对其进行包覆改性,制备聚苯胺包覆改性镍纤维,以改善镍纤维的电性能。主要探究了掺杂剂种类、浓度、镍纤维长径比以及搅拌速率等因素对聚苯胺包覆镍纤维效果的影响,利用核磁共振、能谱仪和扫描电镜对产物进行元素和形貌分析,采用四探针电阻率测试仪测试聚苯胺包覆镍纤维的电性能。结果表明:以0.1mol/L盐酸为掺杂剂,将长径比为8mm的镍纤维在0～5℃下以60r/min的转速聚合得到聚苯胺包覆镍纤维材料,其包覆层致密均匀,且得到最大的电导率,其值为2.62×103S/cm。     

聚苯胺/五氧化二钒插入型杂化纳米复合材料的合成与表征

用原位氧化聚合法将聚苯胺分子链插入层状五氧化二钒的片层中，从而制得了一系列聚苯胺／五氧化二钒(PAn／V2O5)杂化纳米复合材料。采用WAXD、FT-IR、TGA及四探针电导率测量等手段对产物进行表征，结果表明，聚苯胺分子以单层形式在受限的纳米空间(五氧化二钒的片层中)生成，聚苯胺以伸展的单分子链存在，自由电子得到充分离域，PAn／V2O5杂化材料室温电导率在10^-3S／cm～10^-2S／cm之间。     

漂珠/钡铁氧体/聚苯胺复合材料的电磁性能及吸波机理研究

采用溶胶-凝胶自蔓延燃烧法制备了漂珠/钡铁氧体磁性粉体,并以此为核,再利用原位掺杂聚合法制备出兼具电性能和磁性能的漂珠/钡铁氧体/聚苯胺复合材料。通过扫描电镜(SEM)、红外光谱(FT-IR)、X射线衍射(XRD)、振动样品磁强计(VSM)和矢量网络分析仪(VNA)等表征手段,分析了该材料的微观形貌、结构、电磁性能及吸波性能。结果表明,制备的漂珠/钡铁氧体/聚苯胺复合材料表层呈珊瑚状结构,存在聚苯胺和钡铁氧体的特征衍射峰;复合材料的磁性能随聚苯胺掺杂量的增加而减弱,但吸波性能却随之增强;当吸波层厚度为1.2mm、频率为16.4GHz时,样品的吸收峰值可达-42.94dB。     

导电导磁聚苯胺包覆短碳纤维的研究

采用磁性物质结合导电聚苯胺(PANI)层包覆短碳纤维(SCF)制备出导电导磁的短碳纤维,以改善SCF的电磁性能。采用扫描电子显微镜(SEM)结合能谱(EDS)表征了改性SCF的表面形貌、结构,利用PNA-L N5230A微波网络测试仪测定了其在频率2GHz以下的复介电常数和复磁导率。结果表明:在SDBS和油酸为1.0g处理磁流体,HCl用量为0.2mol/L,Fe3O4含量为3.2g时,聚合温度为10℃,反应时间为12h,可制得包覆层均匀、致密的导电聚苯胺/磁性物质包覆改性的短碳纤维。改性后,其介电性能有所下降,磁损耗有所增大。     

多孔聚苯胺/乙炔炭黑复合物的制备及其超级电容特性

采用乙炔炭黑吸附原位聚合方法制备了聚苯胺/炭黑复合材料.利用红外光谱仪、扫描电镜(SEM)及电化学工作站对其结构、形貌及电容特性进行了表征.研究结果表明,聚苯胺/炭黑(PAn/CB)和聚苯胺/氧化炭黑(PAn/CBO)复合物均呈现多孔结构.由于PAn/CBO复合物为纤维状形貌,显示出了更好的超级电容特性,在5mA/cm2放电电流下其放电比电容高达424 F/g.     

导电导磁改性短碳纤维的制备及电磁特性的研究

对短碳纤维进行氧化处理后,采用原位氧化沉淀聚合法使苯胺/磁流体或者苯胺/磁粉在其表面进行包覆反应,制备出具备有一定长径比的导电导磁改性短碳纤维.采用扫描电镜、X射线能谱及X射线衍射对改性碳纤维的形貌、化学组成进行了分析,利用PNA-LN5230A微波网络测试仪测定了其在频率2GHz以下的复介电常数和复磁导率,对比分析了两种不同方法制备的改性碳纤维的电磁参数以及2mm厚度下的吸收损耗.结果表明:聚苯胺/磁流体包覆的碳纤维(改性SCF-A)包覆层完整、致密,Fe含量为2.86at%;聚苯胺/磁粉包覆碳纤维(改性SCF-B)的包覆层外观完整、比较松散,Fe含量为3.12at%.改性SCF-A的复介电常数的实部大于改性SCF-B,但其虚部则小于改性SCF-B;改性SCF-B的复磁导率整体大于改性SCF-A.在频率2GHz以下,改性SCF-A的最大吸收损耗为3.06dB,改性SCF-B的最大吸收损耗为4.14dB.     

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.