聚醚氨酯结构与阻尼性能的研究（Ⅱ）

在前文利用动态粘弹仪讨论聚醚氨酯结构与阻尼性能关系的基础上，进一步探讨了由聚醚氨酯作为阻尼层，高模量环氧复合材料作为约束层构成的约束阻尼结构的阻尼性能。结果表明，聚醚氨酯结构对约束阻尼结构的阻尼性能影响很大；其模量也影响材料与金属复合后的阻尼性能，而且复合后的损耗因子峰值温度（Ｔａ）往往较聚醚氨酯的玻璃化温度（Ｔｇ）高２０℃左右；适当的软硬段配比可获得在－２０℃～＋６０℃宽温域内性能优良的阻尼材料     

水性聚氨酯/丙烯酸酯基多维度导电银浆的制备及低温固化特性

采用醇热法制备了纳米银颗粒、纳米银线和微米银片，对其进行多维度配合作为复合导电填料，以水性聚氨酯/丙烯酸脂复合树脂(WPUA)为载体和黏结相，采用搅拌混合法制备了水性树脂基多维度低温固化导电银浆。利用透射电镜、扫描电镜、水接触角测试和电阻测试，研究了不同固化温度对导电银浆成膜后的力学性能、导电性能及亲疏水特性的影响。结果表明，随着固化温度的上升，银浆漆膜的硬度、附着力及耐水性逐渐增加，WPUA基银浆漆膜的硬度在120℃时可达到3H等级，附着力在100℃可达到1等级，水接触角在140℃时可以达到93°；而WPUA银浆漆膜的电阻率随着固化温度的上升，呈现先增加后减小的趋势，在固化温度为160℃时的电阻率为0.19×10^-3Ω·cm。文中制备的多维度复合导电银浆在柔性电子印刷领域有着很好的应用前景。     

粘结纳米复相磁性材料制备及性能的研究

采用磁粉晶化和粘结工艺制备纳米复相磁材的方法，研究了热处理工艺和粘结剂含量对纳米晶磁体磁性能的影响，结果表明热处理温度、热处理时间、粘结剂含量明显的影响纳米晶的形成及其磁性能。热处理为700℃、粘结剂含量在2％～3％（质量分数）时，纳米复合磁体可以获得较好的磁性能。该研究方法工艺简单，成本较低，具有一定的实用价值。     

纳米节能材料成型压缩变化及其绝热试验

以纳米SiO2粉末与高折射率矿物粉末、增强纤维及高温收缩抑制剂,经千法混合后压制成型,制备较大体积密度的纳米节能材料。通过压制试验,研究了原料混合粉末在模具内的体积变化,探讨了物料中的气体对体积收缩率的影响,得到了材料体积密度与成型压力的关系。通过背温试验,将体积密度450kg／m3的纳米节能材料与现有市场上的复合反射绝热材料的绝热效果进行对比。结果表明,对于同样20mm厚度的两种材料,纳米节能材料热面温度稳定在668℃时,其冷面温度只有140℃。而复合反射材料热面温度稳定在641℃时,冷面温度高达229℃。纳米节能材料的绝热效果明显优于复合反射材料。     

纳米TiO_2的表面改性及MF/纳米TiO_2复合树脂的制备

采用硅烷偶联剂KH550对纳米TiO2进行表面改性,将改性纳米TiO2与三聚氰胺甲醛树脂(MF)混合,制备MF/纳米TiO2复合树脂。红外分析表明偶联剂成功接枝于纳米TiO2表面;热失重分析得出表面改性的最佳工艺为:改性剂的添加量2%,改性温度70℃,改性时间120min;透射电镜分析表明纳米TiO2的表面改性提高了其在有机溶剂中的分散性;研究TiO2添加量对MF/纳米TiO2复合树脂的粘度、固化时间、固化温度和抗菌性的影响,结果表明TiO2的添加对树脂固化时间和固化温度影响很小,但能显著提高材料的粘度和抗菌性能。     

纳米孔玻态炭-超级电容器的新型电极材料I. 固化温度对其结构和电容性能的影响

玻态炭的电导率高,机械性能好,但因制备费时长而价格昂贵,透气率极低而无法整体活化,难以用作电化学电容器的电极材料。为此提出了一种具有纳米结构多孔玻态炭的快捷制备方法:在热塑性酚醛树脂中加入适量的固化剂,经加热固化、粉碎研磨、模压成型、快速升温炭化、活化。这种酚醛树脂基纳米孔玻态炭整体呈多孔结构,由于比表面较大而可得大比容量,由于块体电导率较高和孔结构合适而可得大比功率。着重研究了制备方法中影响其电化学电容性能的重要影响因素-固化温度。研究结果表明,炭化物的孔隙率随固化温度升高而增大,利于活化剂分子向内扩散,增强活化反应的造孔作用。所制纳米孔玻态炭的结构介于玻态炭和活性炭之间,固化温度越高,孔结构越发达,其结构越趋近于活性炭。225℃以上固化,产物的孔结构和电化学性能较好,因此225℃作为固化温度较适宜。     

SiO2纳米粒子对铜导电胶连接强度的影响

以环氧树脂为基体，间苯二胺和二氨基二苯甲烷的低融点混合物为固化荆，铜粉为导电填料，制备了热固化各向同性导电胶。研究了固化温度、固化时间及固化荆、纳米SiO2粒子添加量对连接性能的影响。在固化温度为145℃．固化时间为2h时．导电胶连接强度达到20MPa。体系中添加适量的纳米SiO2粒子，连接强度提高到25MPa。SiO2粒子均匀地分散在环氧树脂基体的三维立体网状大分子链中，起到分散应力，吸收冲击能．阻止裂纹扩展的作用。     

静电纺纤维素纳米晶体/壳聚糖-聚乙烯醇复合纳米纤维的制备与表征

通过探索纤维素纳米晶体（CNC）添加量对壳聚糖-聚乙烯醇（CS-PVA）基体性能的影响,为静电纺CNC/CS-PVA复合纳米纤维的制备提供理论支撑。以CNC、CS和PVA为原料,采用静电纺丝法成功制备不同CNC含量（质量分数）的静电纺CNC/CS-PVA复合纳米纤维,并通过SEM、TGA和FTIR等分析手段对CNC/CS-PVA复合纳米纤维的微观结构和性能进行了表征。结果表明：添加CNC后静电纺CNC/CS-PVA复合纳米纤维直径变大,表面变粗糙,力学性能和热学性能提高;随着CNC含量的增加,静电纺CNC/CS-PVA纤维的杨氏模量（E）和抗拉强度（σ）先增强后减弱,而外延起始温度继续上升。当CNC含量为3wt%时,静电纺CNC/CS-PVA复合纳米纤维力学性能最好,相比于CS-PVA复合纳米纤维,E和σ分别提高了43.9%和24.8%;当CNC含量为20wt%时,静电纺CNC/CS-PVA复合纳米纤维直径分布不均匀,可以观察到单根纤维表面存在少量的球状结构物质,同时外延起始温度达到328.83℃;FTIR分析得出,CNC与CS和PVA之间只存在分子间的相互作用而没有发生化学反应;随着溶液的酸性减弱,碱性增强,不同CNC含量的静电纺CNC/CS-PVA复合纳米纤维稳定性逐渐提高,而CNC含量对其稳定性影响不大。     

纳米石墨薄片的修饰及对双马来酰亚胺树脂性能影响

通过扫描电镜（SEM）和差示扫描量热（DSC）对纳米石墨薄片修饰前后的微观结构和对双马来酰亚胺树脂固化性能影响进行分析,实验得出纳米石墨薄片的修饰有利于其在树脂中的分散性能,并且纳米石墨薄片具有50～100nm厚度,仍保持着网状多孔结构;另还发现纳米石墨薄片改变了双马来酰亚胺树脂的玻璃转化温度和固化性能,还发现纳米石墨薄片与修饰的纳米石墨薄片对树脂性能影响不同。     

聚乙烯醇/纳米二氧化硅复合薄膜的制备及性能

采用改性纳米二氧化硅,利用熔融挤出法制备出聚乙烯醇/纳米二氧化硅复合薄膜,考察了纳米二氧化硅粉体对复合薄膜综合性能的影响。结果表明,改性纳米二氧化硅粉体在聚乙烯醇薄膜中分散均匀,纳米二氧化硅粉体的加入可使聚乙烯醇薄膜的熔融温度降低10℃左右,热分解温度提高30℃,断裂伸长率提高为原来的142%,耐水性提高为原来的2.4倍,且当纳米二氧化硅粉体的添加量在0.3%以上时,聚乙烯醇薄膜材料在200 nm~280 nm波长范围内的紫外线透过率均为零。     

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.