改性钴镁铝类水滑石对乙烯-醋酸乙烯共聚物阻燃和力学性能的影响

采用共沉淀微波晶化法合成了不同量硬脂酸钠表面改性的钴镁铝类水滑石。X射线衍射测试指出合成的所有类水滑石晶体均有高的结晶度,d_(003)值证实了硬脂酸根和硝酸根离子没有插入到类水滑石的层间。红外光谱、扫描电镜和接触角测试均证实了随着改性剂用量的逐渐增加,类水滑石表面硬脂酸钠的负载量也逐渐增加。热分析表明改性剂的负载量对类水滑石的热降解温度有较大的影响。当类水滑石以总质量的20%的比例添加到乙烯-醋酸乙烯共聚物(EVA)中制成复合材料时,氧指数和力学测试指出钴离子的加入,使得钴镁铝类水滑石比镁铝类水滑石对复合材料氧指数和断裂伸长率均有明显的提高。硬脂酸钠以前驱体质量的2%进行改性的钴镁铝类水滑石/EVA复合材料的强度、韧性和阻燃性能表现最好。     

改性钴镁铝类水滑石对乙烯-醋酸乙烯共聚物阻燃和力学性能的影响EI北大核心CSCD

采用共沉淀微波晶化法合成了不同量硬脂酸钠表面改性的钴镁铝类水滑石。X射线衍射测试指出合成的所有类水滑石晶体均有高的结晶度,d_(003)值证实了硬脂酸根和硝酸根离子没有插入到类水滑石的层间。红外光谱、扫描电镜和接触角测试均证实了随着改性剂用量的逐渐增加,类水滑石表面硬脂酸钠的负载量也逐渐增加。热分析表明改性剂的负载量对类水滑石的热降解温度有较大的影响。当类水滑石以总质量的20%的比例添加到乙烯-醋酸乙烯共聚物(EVA)中制成复合材料时,氧指数和力学测试指出钴离子的加入,使得钴镁铝类水滑石比镁铝类水滑石对复合材料氧指数和断裂伸长率均有明显的提高。硬脂酸钠以前驱体质量的2%进行改性的钴镁铝类水滑石/EVA复合材料的强度、韧性和阻燃性能表现最好。     

MgAlCe水滑石的合成及其表征

采用共沉淀水热法合成了MgAlCe三元复合层状氢氧化物。详细探讨了x(Al)/x(Ce)、水热温度及pH值对合成产物物相的影响。通过XRD、TG/DTG、SEM及TEM对制备的水滑石进行分析。结果表明,当x(M2+)/x(M3+)=1.5,x(Al)/x(Ce)=16∶1,pH值=7.9条件下进行多种离子共沉淀,并经140℃、10h水热处理后,得出的产物结晶度较高,物相纯净,具有典型层状结构,并且其热稳定性较好,层间羟基硝酸根失去温度在300～500℃之间,表明其作为阻燃剂具有很大的潜力。     

氧化吸附法合成硝酸根型铜铁铝类水滑石

采用氧化吸附法制备了硝酸根型铜铁铝类水滑石,借助XRD、FTIR、SEM等分析手段研究了样品的结构、形貌及形成机理.结果表明:存在水蒸气的条件下,以碳酸根型铜铁铝类水滑石为前驱体经过500℃焙烧得到的铜铁铝复合氧化物可以氧化吸附NO2,生成Cu(NO3)2.上述样品在干燥器中放置9 d后转化成直径约为5μm的硝酸根型类水滑石.此外,铜铁铝复合氧化物吸附NO2、H2O和O2后也可直接转化成硝酸根型铜铁铝类水滑石,不存在中间相Cu(NO3)2.本文提出的氧化吸附法为制备类水滑石提供了一种新途径.     

NiMgAl类水滑石制备条件研究

采用共沉淀法合成了不同摩尔投料比的NiMgAl类水滑石化合物.测定了Ni、Mg、Al单盐以及不同摩尔比的混合硝酸盐溶液的滴定曲线,考察了加料方式、晶化温度、晶化时间、原料配比对类水滑石合成的影响.通过XRD、IR对合成物进行表征,结果表明,在恒定pH值为8～9,n(Mg Ni)/n(Al)=1～3,n(Mg)/n(Ni)=8～16,晶化温度为65℃,晶化时间6h的条件下即得到晶相单=的NiMgAl-HTLcs;随n(Mg Ni)/n(Al)的增加,类水滑石结构的规整性提高,n(Mg)/n(Ni)比增加,层间距略有减小.     

二元金属类水滑石的合成及其作为前驱体对NOx的吸附性能研究

用共沉淀法合成了多种二元金属类水滑石化合物,对其进行了XRD、IR表征,并测试了焙烧产物对NOx的吸附性能.结果表明,合成的样品都具有典型的水滑石层状结构;二元金属类水滑石化合物MAl-HTlcs(M=Cu,Mg,Zn,Co,Ni)对NOx均具有良好的吸附性能,其中锌铝型类水滑石(摩尔比Zn/Al=3)对NOx的吸附速率及饱和吸附量最大,饱和吸附量为1851mg/g.     

二维层状磁性镁铝水滑石的制备与表征

采用共沉淀法将磁性基质与镁铝水滑石组装制备二维层状磁性镁铝水滑石,考察了在一定的pH值、沉淀生成温度及陈化时间下,不同n(Mg2 )/n(Al3 ),n(Fe2 )/n(Mg2 )比值及焙烧温度对合成磁性镁铝水滑石结构的影响,并借助HRTEM、XRD、VSM、TG-DSC、FT-IR等手段对其晶型结构、磁学性能及结晶度等进行表征,结果表明镁铝水滑石在赋予磁性后,并没有改变其典型的层状结构,证实了将磁性基质与层状材料组装合成的可行性.     

纳米晶Mg-Al水滑石的水热合成及合成机理

讨论了不同的Mg、Al源为起始反应物、反应温度、时间和碱度对水热合成Mg-Al水滑石物相组成和晶粒度的影响. 用XRD、SEM对合成产物进行了表征, 用X射线全谱拟合法计算了Mg-Al水滑石晶粒度. 以MgO和Al(OH)₃为起始反应物, Mg/Al=2,在140℃反应4～10h, 可以制备出高结晶度的单相纳米晶Mg-Al水滑石. Mg-Al水滑石的形成机理可概括为: 水解反应-沉淀成核-晶粒长大. 反应物类型及合成条件会影响前驱物的水解速率和水解程度, 进而影响晶体成核和生长速率,控制物相的组成和晶粒度大小.     

纳米镁铝水滑石的制备及其对聚氨酯阻燃性能的影响

采用液相沉淀法制备纳米镁铝水滑石微粉,利用XRD、TEM和TG对试样进行表征,研究了反应温度、干燥时间以及碳酸根浓度对镁铝水滑石纳米晶的影响.镁铝水滑石微粉经硅烷偶联剂KH550表面改性后填充到聚醚多元醇组合料中,采用原位聚合法制备出镁铝水滑石/软质聚氨酯纳米复合材料,研究了纳米镁铝水滑石对聚氨酯的阻燃效果及阻燃机理,并与Al(OH)_3阻燃效果进行对比.实验结果表明,晶粒尺寸随反应温度的升高而增大;干燥5h镁铝水滑石的热分解性能较好;适当提高碳酸根浓度可以改善镁铝水滑石晶体规整度;硅烷偶联剂KH550用量为5%时对镁铝水滑石表面改性效果最好;镁铝水滑石阻燃剂填充软质聚氨酯复合体系的阻燃效果要优于Al(OH)_3阻燃剂.     

纳米水滑石的结构表征及其对氯离子的吸附性能

以天然菱镁矿为原料,采用尿素法制备纳米Mg-Zn-Al水滑石(LDH)、Zn-Mg-Al-Fe水滑石,采用XRD、SEM、N2吸附-脱附对水滑石的结构特征、晶粒尺寸进行表征,并利用水滑石的层间阴离子交换性及结构"记忆效应",来研究焙烧态水滑石(CLDH)对溶液中氯离子的吸附性能。结果表明:Zn-Mg-Al-LDH结晶度比Mg-Al-LDH、Zn-Mg-Al-Fe-LDH高,同时Zn-Mg-Al-LDH的粒径非常均匀,尺寸在20nm左右,为层片状结构,而且其晶体结构呈现花瓣状结构;在Mg-Al-CLDH中,随着n(Mg/Al)的增加,溶液中Cl~-的去除率逐渐提高,且在n(Mg/Al)=4时去除率最大,为85.96%;当n(M~(2+)/M~(3+))固定为2时,Zn-Mg-Al-CLDH对Cl~-的去除率要比Mg-Al-CLDH对Cl~-的去除率高13.25%,但Zn-Mg-Al-Fe-CLDH的去除率却比Mg-Al-CLDH低32.53%;焙烧态水滑石n(Zn/Mg/Al)=1∶1∶1时,有较大的比表面积837.183m~2/g,较大的孔容为0.496cc/g,其相应吸附能力也较大。     

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.     

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.     

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.     

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.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.