改性多壁碳纳米管/聚氨酯形状记忆复合材料的制备及性能

利用表面引发原子转移自由基聚合(SI-ATRP)的方法在多壁碳纳米管(MWNT)表面接枝聚甲基丙烯酸甲酯(PMMA),接枝改性后的多壁碳纳米管通过原位聚合法与形状记忆聚氨酯(SMPU)合成SMPU/MWNT-PMMA复合材料。采用FTIR、SEM、TGA、DMA等方法表征材料的结构与性能,并测试其形状记忆性能。结果表明,随着MWNT-PMMA含量的增大,复合材料的力学性能显著改善,最大拉伸强度达到81.30MPa,玻璃化转变温度(Tg)增大,热稳定性增强,且复合材料具有电热双敏性,循环四次后形状固定率和形状恢复率均在95%以上,具有较好的形状记忆性能。     

脂肪族聚氨酯弹性体/蒙脱土复合材料的制备与性能

使用原位插层聚合法制备了一系列不同有机蒙脱土含量的基于异佛尔酮二异氰酸酯的脂肪族聚氨酯弹性体/蒙脱土纳米复合材料,通过X射线衍射(XRD)、差示扫描量热测试(DSC)、热重分析(TGA)等研究了有机蒙脱土含量对脂肪族聚氨酯弹性体结构与性能的影响。XRD结果表明,成功地合成了聚氨酯/蒙脱土插层型纳米复合材料。TGA结果表明,纳米复合材料的热稳定性随着有机蒙脱土含量的增加而提高。有机蒙脱土对聚氨酯基体有较好的增强和增韧作用,而当有机蒙脱土含量为7%时,纳米复合材料的力学性能最佳。     

取代度和改性MMT对纤维素基高吸水性纳米复合材料性能的影响

以麦秸秆为原料制备羧甲基纤维素(CMC),采用水溶性丙烯酸类单体对其接枝共聚,并添加不同有机季铵盐插层改性的蒙脱土(MMT),通过原位插层聚合制备CMC/丙烯酸类聚合物/OMMT高吸水性纳米复合材料。考察了碱和氯乙酸用量对CMC取代度和增重率的影响,探讨了CMC取代度与产物接枝率、接枝效率、吸水率之间的关系,分析了不同季铵盐改性MMT对材料性能的影响。通过红外光谱、X射线衍射等对纳米复合材料的结构进行表征,结果表明,在OMMT存在的条件下,CMC与丙烯酸类单体成功发生了接枝聚合;随着季铵阳离子碳链取代基的体积增大,改性蒙脱土的层间距越大;所制备的纳米复合材料属于剥离型纳米复合材料。     

蒙脱土的酸化及有机化对聚氨酯/蒙脱土纳米复合弹性体材料性能的影响

利用本体聚合方法制备了聚氨酯/蒙脱土纳米复合材料。通过对蒙脱土进行酸化和有机化两步处理,发现酸化处理不仅能有效地扩大蒙脱土的片层间距,还能有效地防止蒙脱土在聚氨酯本体聚合时对异氰酸酯基三聚副反应的催化作用。利用DSC、TGA、XRD等手段对聚氨酯/蒙脱土纳米复合材料的力学性能、热性能、内部结构进行了表征,发现酸化及有机化蒙脱土在聚氨酯内部能形成纳米片层结构,提高了复合材料的力学性能。     

聚氨酯改性聚乳酸/蒙脱土复合材料的制备与表征

采用溶液共混法,用聚氨酯(PU)和蒙脱土(MMT)对聚乳酸(PLA)进行改性.通过综合热分析(TGA＆DSC)、红外吸收光谱(IR)以及力学测试(FP)对改性聚乳酸(PLA)的性能进行了表征.结果显示,聚氨酯和蒙脱土与聚乳酸均有较好的相容性,复合材料的稳定性较好,而且聚氨酯/蒙脱土/聚乳酸复合材料较纯聚乳酸的力学性能有了较明显的提高,强度和韧性均较好.     

蒙脱土填充木塑复合材料的弯曲性能和蠕变特性

对蒙脱土进行有机插层改性制得有机蒙脱土(OMMT),用硅烷接枝木粉制备了有机蒙脱土/木粉/聚氯乙烯(OMMT/WF/PVC)纳米复合材料。加入的接枝木粉与OMMT分散在界面上起增强作用,有助于提高复合材料性能。用质量分数1.5%的偶联剂处理木粉,添加质量分数1.5%的OMMT时,复合材料的弯曲性能和抗蠕变性最好。用KWW模型和广义Voigt模型分析了蠕变曲线。     

纳米蒙脱土的制备及在超高分子量聚乙烯中的应用

采用插层聚合的方法对蒙脱土进行了层间改性,通过X射线衍射仪、转矩流变仪等,对改性蒙脱土的层间结构进行了表征,随着单体插层、层间聚合、熔融共混的进行,蒙脱土的层间距不断增大,表明蒙脱土发生了层间剥离,与高分子聚合物形成了纳米复合材料。同时比较了不同改性的蒙脱土对聚合物扭矩的影响,苯乙烯单体插层聚合改性的蒙脱土对聚合物体系扭矩影响最大。     

PET/二次改性蒙脱土纳米复合材料的制备与力学性能

用甲苯-2,4-二异氰酸酯(TDI)改性磷系蒙脱土(PMMT),并用二次改性的PMMT改性聚对苯二甲酸乙二醇酯(PET).分析改性后的复合材料,结果表明TDI与蒙脱土表面有化学键形成,并且由于TDI的包埋,蒙脱土层间距从3.62 nm下降到3.25 nm.在原位反应中表层高活性的终端氰酸酯基能提高PMMT和PET之间的相容性,并且使得蒙脱土在聚合物基体中均匀分散.同时,层间的对苯二甲酸(PTA)与乙二醇(EG)反应所产生的聚合热能够使粘土层扩张.二次改性后的蒙脱土赋予复合材料更好的力学性能,拉伸强度提高38％以上,弯曲强度、弯曲模量都提高40％以上,但断裂伸长率有所下降.     

蒙脱土/ 硅烷改性木粉/ PVC 复合材料

用硅烷YH-62 对木粉(WF) 和插层蒙脱土(OMMT) 进行表面改性, 熔融共混挤出制备了OMMT/ 硅烷改性木粉(STWF) / 聚氯乙烯( PVC) 复合材料。分析了硅烷改性和添加蒙脱土含量对材料力学性能的影响。用X射线衍射(XRD) 、透射电镜( TEM) 和扫描电镜(SEM) 观察了蒙脱土的插层和分散效果, 用傅立叶红外光谱( FTIR) 、X 射线光电子能谱(XPS) 研究了硅烷改性效果, 分析了表面接枝反应机理。结果表明, 硅烷偶联剂与木粉形成了有效的化学键, 并能够与OMMT 表面产生化学连接, 改善木粉与PVC 及蒙脱土间的界面相容性, 提高了木塑材料的力学性能。在适量加入OMMT 后, 木塑材料的力学性能得到了进一步改善。但含量过高, 会形成厚界面层, 甚至使OMMT 和木粉团聚, 分布不均匀, 引起性能降低。      

淀粉接枝丙烯酰胺和丙烯酸／蒙脱土纳米复合吸水材料的合成

淀粉糊化于AA和AM的水溶液中,分散十六烷基三甲基溴化铵改性后的蒙脱土于此水溶液中进行单体原位插层接枝聚合,制得淀粉接枝丙烯酰胺和丙烯酸/蒙脱土纳米复合吸水材料。X射线衍射(XRD)结果发现,复合材料中蒙脱土片层(001)面的层间距增大到2.37 nm,形成了剥离型纳米插层复合吸水材料。TG分析表明,该复合吸水材料的分解温度比普通淀粉接枝丙烯酰胺和丙烯酸吸水材料提高了70℃。DSC结果表明,随着吸水剂中MMT含量的增加(0%、2%、5%、8%),复合吸水材料的Tg逐渐升高(108℃、118℃、130℃、140℃)。通过SEM观察发现复合吸材料形成了致密的网状结构,蒙脱土与高分子基体有较多粘连。     

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...     

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.     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.