DHDOPO接枝改性多壁碳纳米管及其对聚乳酸性能的影响

首先将多壁碳纳米管(p-MWCNTs)用混合浓酸氧化成羧基化MWCNTs(MWCNTs-COOH),然后与氯化亚砜(SOCl_2)反应得酰氯化MWCNTs(MWCNTs-COCl);将9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与二乙醇胺(DEA)反应制备DOPO的衍生物DHDOPO;再将DHDOPO与MWCNTs-COCl进行接枝反应得表面功能化的MWCNTs(MWCNTs-COO-DH);最后经熔融共混法制备聚乳酸(PLA)/MWCNTs-COO-DH复合材料。用核磁共振氢谱和透射电子显微镜表征MWCNTs-COO-DH的结构和微观形貌;用电子万能试验机、扫描电子显微镜、微型燃烧量热计等测定PLA/MWCNTs-COO-DH复合材料的力学性能、冲击断面形貌、燃烧性能及残炭层形貌。结果表明,实验成功合成了目标产物DHDOPO,并将其接枝到MWCNTs表面形成了典型核-壳结构的MWCNTs-COO-DH;适量的MWCNTs-COO-DH可均匀分散在PLA基体中形成良好的界面结合;质量分数为0.1%的MWCNTs-COO-DH可显著提高PLA的力学性能,并能降低其可燃性和火灾危险性。     

碳纳米管的表面改性对环氧树脂低温(77 K)冲击性能及热膨胀系数的影响

采用混酸氧化及表面接枝改性的方法制备了表面含不同官能团的多壁碳纳米管(MWCNTs), 并研究了不同MWCNTs对环氧树脂的低温(77 K)抗冲击性能及热膨胀系数(CTE)的影响。结果表明: 通过接枝反应将—NCO基团封端的PEO齐聚物引入MWCNTs表面, 可提高MWCNTs在环氧树脂基体中的分散性, 加强MWCNTs与环氧树脂的界面作用; 相对于纯环氧树脂, 添加质量分数为0.5%的纯MWCNTs、 氧化MWCNTs和表面接枝MWCNTs改性后的环氧树脂的低温冲击强度分别升高了10.27%、 26.13%和32.95%, 而CTE则分别降低了14.79%、 29.59%和40.29%。这表明表面接枝改性MWCNTs可明显提高环氧树脂基体的低温抗冲击性能并降低环氧树脂在玻璃化转变温度下的CTE。     

CNTs的表面改性及其在环氧树脂复合材料中的应用

首先采用浓硫酸/浓硝酸对多壁碳纳米管(MWCNTs)进行混酸氧化处理,再将氧化后的CNTs与DOPO改性后的硅烷偶联剂(DOPO-KH560)进行改性,制备了DOPO-KH560表面化学修饰的MWC-NTs。在此基础上,将改性前后的CNTs分散在环氧树脂体系中,制成样条,研究了处理前后样条力学性能的变化。材料表面结构的红外光谱(FT-IR)分析表明,CNTs混酸氧化成功,表面成功引入了羟基和羧基,而且DOPO-KH560成功接枝到酸化CNTs上。材料微结构的透射电子显微镜(TEM)观察表明,酸化后MWCNTs被截短,分散性变好,接枝DOPO-KH560后CNTs表面包覆了一层低聚物。对处理后的样条进行力学性能测试并用扫描电镜(SEM)分析观察断面形态的变化。结果表明,环氧树脂中加入CNTs,能有效地增加环氧树脂的韧性和强度,且加入原CNTs、氧化CNTs、改性后的CNTs时增强增韧效果逐渐增加,加入最终CNTs后环氧树脂的增强增韧效果最明显。     

氧化-还原聚合法制备多壁碳纳米管/甲基丙烯酸甲酯杂化粒子的研究

通过酸氧化和酰胺化反应在多壁碳纳米管(MWCNTs)表面引入伯氨基团,再采用表面氧化-还原聚合法在MWCNTs表面接枝甲基丙烯酸甲酯(MMA)。利用红外、拉曼、热失重和透射电镜对产物进行表征,考察了反应时间、引发剂用量和单体用量对接枝率的影响。结果表明:通过伯氨基团和过硫酸铵(APS)所构成的氧化-还原体系可以有效引发MWCNTs表面MMA接枝聚合。在反应时间16h,聚合温度为50℃,APS用量为6mmol/L,MMA为水的5%(质量分数)时,接枝率可达28.6%。改善了MWCNTs在聚偏氟乙烯铸膜液中的分散性。     

改性碳纳米管处理碳纤维的效果表征

采用浓硫酸/浓硝酸氧化处理多壁碳纳米管(MWCNTs),再将氧化后的碳纳米管与硅烷偶联剂(KH560)进行接枝,制备了硅烷偶联剂表面化学修饰的MWCNTs。在此基础上,将改性前后的碳纳米管分散在环氧树脂体系中,涂覆处理碳纤维。研究处理前后碳纤维力学性能和界面性能的变化。通过红外光谱(FTIR)和透射电镜(TEM)分析,表明KH560已成功接枝到多壁碳纳米管上;通过分散性实验证明了改性后的碳纳米管分散性提高;对处理后的碳纤维进行力学性能测试,并用扫描电镜(SEM)观察分析断面形态变化,结果表明,当碳纳米管的含量为0.5%时,改性碳纳米管处理的碳纤维拉伸强度和拉伸模量分别提高23.83%和7.11%,界面性能增强。     

CaCO_3/Al_2O_3/MWCNTs环氧复合涂层性能研究

利用KH560对碳酸钙(CaCO_3)、氧化铝(Al_2O_3)、酸化后的多壁碳纳米管(MWCNTs)表面进行接枝改性,并制备了CaCO_3/Al_2O_3/MWCNTs/环氧树脂(EP)复合涂层。采用傅里叶变换红外光谱(FT-IR)、热重分析仪(TG)和EDS分析对改性前后的无机填料进行表征,使用电化学阻抗谱(EIS)、抗冲击试验、高温高压实验测试复合涂层的附着力、耐腐蚀等性能。同时用扫描电子显微镜(SEM)观察复合涂层表面形貌。结果表明,KH560成功的接枝在3种无机填料表面,当MWCNTs的质量分数为2%时,CaCO_3/Al_2O_3/MWCNTs/EP复合涂层的分散性最好,性能最优。     

多壁碳纳米管的表面磺基化修饰

用H_2SO_4与HNO_3(体积比为3∶1)的混酸对原始多壁碳纳米管(p-MWCNTs)进行修饰,使p-MWCNTs表面氧化生成酸化多壁碳纳米管(a-MWCNTs);通过N,N′-二环己基碳二胺(DCC)缩合作用,使对氨苯磺酸的氨基与a-MWCNTs表面羧基缩合脱水得到磺化多壁碳纳米管(s-MWCNTs)。采用热压成型法在聚醚醚酮(PEEK)基体中分别加入不同改性的多壁碳纳米管(MWCNTs)制得MWCNTs/PEEK复合材料。在磺化过程中研究了DCC用量、反应时间和对氨基苯磺酸用量对s-MWCNTs表面接枝率的影响。采用热重分析、场发射电子显微镜、红外和拉曼光谱对不同改性MWCNTs进行形貌和结构分析。结果表明,在a-MWCNTs用量为0.3g,DCC用量为0.5g、反应时间为6h和对氨基苯磺酸用量为0.3g条件下,所得s-MWCNTs之间堆积松散,分散性较好,失重率最大。动态力学分析表明,s-MWCNTs/PEEK复合材料的储能模量显著增加。     

多壁碳纳米管改性氰酸酯/环氧树脂基纳米复合材料的力学性能

用强酸氧化法与等离子体镀膜法分别对原始多壁碳纳米管(MWCNTs)进行表面修饰,制备了MWCNTs改性氰酸酯/环氧树脂基纳米复合材料。对复合材料的断裂面进行SEM分析,研究了表面处理方法对复合材料室温及低温力学性能的影响。结果表明,经等离子体镀膜表面修饰后的MWCNT在基体中分散更为均匀,与基体的界面结合力更强。经等离子体镀膜表面改性后的MWCNTs复合材料,当MWCNTs质量分数为0.3%时,其室温及低温拉伸强度、弹性模量和冲击强度较纯氰酸酯/环氧树脂基体均有不同程度的提高。     

超支化聚酰胺改性多壁碳纳米管的制备与表征

采用硫酸和硝酸的混合液氧化多壁碳纳米管(MWCNTs),再用二氯亚砜将氧化产生的羧基酰氯化,进一步与带有活性端基的超支化聚酰胺(HBPA)反应,得到超支化聚酰胺修饰的碳纳米管。采用红外光谱(FT-IR)、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电镜(TEM)及热重分析(TGA)对化学修饰的碳纳米管进行了表征。结果表明HBPA接枝到碳纳米管上,在碳纳米管表面形成聚合物层。由TGA曲线计算出改性碳纳米管的接枝率约为27%;SEM结果表明接枝后的碳纳米管在无水乙醇中的分散性更好。     

多壁碳纳米管的氧化剪断处理及其分散性

利用混合强酸对多壁碳纳米管(MWCNTs)进行氧化浸泡处理。采用透射电镜、原子力显微镜、Raman光谱、红外光谱等分析手段对处理前后的MWCNTs进行表征,探索氧化浸泡时间对MWCNTs微观形貌及剪断过程的影响,并对氧化剪断后短碳管在水溶液中的分散性进行研究。结果表明,MWCNTs在混酸中浸泡72 h左右可以使其从缺陷处剪断,形成管长为200~1 500 nm的短直管,且碳管表面及端口处嫁接上羟基和羧基活性基团。由于极性官能团的存在,使得MWCNTs的等电点从4.5下降到3.5,沉降实验和分光光度测试显示短碳管在有适量阴离子型表面活性剂存在的pH≈2的水溶液中超声振荡40min后具有良好的分散效果。     

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.