脱掺杂聚苯胺纳米纤维/低密度聚乙烯复合材料的制备及介电性能EI北大核心CSCD

采用苯胺单体与氧化剂"迅速混合"的聚合方法制备了盐酸掺杂的聚苯胺(PANI)纳米纤维,后经氨水脱掺杂得到脱掺杂聚苯胺纳米纤维,利用扫描电子显微镜观察了脱掺杂PANI纳米纤维的形貌。通过熔融共混的方式配制出不同PANI用量的脱掺杂PANI纳米纤维/低密度聚乙烯(LDPE)复合材料,采用傅里叶变换红外光谱研究了纳米复合材料的结构,并测量了不同温度、不同PANI用量的脱掺杂PANI纳米纤维/LDPE复合材料的电导率、击穿强度和不同频率下相对介电常数及介电损耗。研究结果表明,实验得到了直径均一的脱掺杂PANI纳米纤维;添加适量的脱掺杂PANI纳米纤维的LDPE复合材料电导率降低;添加少量脱掺杂PANI纳米纤维复合材料的击穿强度没有降低;复合材料的相对介电常数先降低后增大,但介电损耗一直在增大。     

脱掺杂聚苯胺纳米纤维/低密度聚乙烯复合材料的制备及介电性能

采用苯胺单体与氧化剂"迅速混合"的聚合方法制备了盐酸掺杂的聚苯胺(PANI)纳米纤维,后经氨水脱掺杂得到脱掺杂聚苯胺纳米纤维,利用扫描电子显微镜观察了脱掺杂PANI纳米纤维的形貌。通过熔融共混的方式配制出不同PANI用量的脱掺杂PANI纳米纤维/低密度聚乙烯(LDPE)复合材料,采用傅里叶变换红外光谱研究了纳米复合材料的结构,并测量了不同温度、不同PANI用量的脱掺杂PANI纳米纤维/LDPE复合材料的电导率、击穿强度和不同频率下相对介电常数及介电损耗。研究结果表明,实验得到了直径均一的脱掺杂PANI纳米纤维;添加适量的脱掺杂PANI纳米纤维的LDPE复合材料电导率降低;添加少量脱掺杂PANI纳米纤维复合材料的击穿强度没有降低;复合材料的相对介电常数先降低后增大,但介电损耗一直在增大。     

原位聚合 ( PSS/ PANI) n复合膜的静电层2层自组装

基于静电相互作用 , 从苯胺单体出发原位聚合、现场掺杂、层2层自组装制备多层聚苯乙烯磺酸钠( PSS) /聚苯胺 ( PANI) 复合膜。为了明确控制 PSS/ PANI复合膜纳米结构的因素 , 以紫外2可见 (UV2Vis) 光谱跟踪 PSS/ PANI复合膜的成膜过程 , 系统地研究了基片性质、 氧化剂用量及沉积时间等溶液因素对单个双层复合膜纳米结构的影响 , 得到了制备单个双层复合膜的较优条件。在此基础上变换苯胺单体浓度 , 制备了不同纳米结构的多层复合膜 ( PSS/ PANI) n, 并用原子力显微镜 (AFM) 、 扫描电镜 (SEM) 及椭偏仪等对该多层复合薄膜的形貌结构进行了表征。结果表明 , 通过控制沉积条件 , 每双层复合膜的厚度可控制在 40～100 nm , 电导率可达- 12. 675 mS·cm , 并且可制备增长均匀的 8 个双层的 ( PSS/ PANI) 8复合膜。热失重分析 ( TGA) 表明 , ( PSS/ PANI) n多层复合膜的热稳定性优于普通 PSS/ PANI复合膜。     

原位聚合法制备聚苯胺/多壁碳纳米管纳米复合材料及其热稳定性能

为合成树脂/聚苯胺(PANI)/多壁碳纳米管(MWCNTs)三元纳米复合电磁屏蔽材料的制备提供理论依据,在苯胺的盐酸溶液中,以过硫酸铵为氧化剂,采用原位聚合法制备PANI/MWCNTs纳米复合材料,并对PANI/MWCNTs纳米复合材料的结构、形貌以及热稳定性能进行研究。结果表明:PANI成功包覆在MWCNTs表面,且PANI和MWCNTs存在一定的相互作用;PANI在MWCNTs表面不均一性的有序生长,有效地改善了MWCNTs的分散性;PANI/MWCNTs纳米复合材料的热分解起始温度达到280℃,当温度为364℃时,热失重率为20%,说明PANI/MWCNTs纳米复合材料具有良好的热稳定性。     

乳液共混法制备PANI/PAN复合纳米纤维

采用乳液共混法,在N,N二甲基甲酰胺( DMF)中进行聚苯胺(PANI)的乳液聚合,并将该乳液与聚丙烯腈(PAN)的DMF溶液共混形成PANI/PAN复合分散体系;通过静电纺丝技术制备PANI/PAN复合纳米纤维.利用傅里叶红外测试仪(FT-IR)、紫外可见分光光度计(UV-vis)对乳液聚合产物进行了鉴定;利用数显电...     

柔性智能聚苯胺/聚氨酯导电纳米纤维的制备及性能

利用静电纺丝技术制备聚氨酯(PU)纳米纤维,采用原位聚合法在纤维表面聚合导电聚合物聚苯胺(PANI),得到具有优良导电性能的柔性PU/PANI复合纳米导电纤维。通过扫描电镜观察到表面均匀包覆聚苯胺的复合纳米纤维;红外光谱结果证明在聚氨酯纳米纤维表面成功合成了聚苯胺。通过实验可知,聚苯胺最佳聚合工艺为苯胺单体浓度为1.3 mol/L、聚合时间为120 min。导电性能测试发现,PU/PANI复合纳米纤维导电性能优良,电导率可达7.6×10-1S/cm,经聚合后力学性能较为稳定。将PU/PANI导电纳米纤维制成简易柔性传感器件,探究发现PU/PANI导电纳米纤维具有柔性应变电学性质,且反应灵敏。     

SiO2不同的掺杂方式对聚氨酯树脂材料性能的影响

采用溶胶凝胶法制备纳米SiO2颗粒,然后在聚氨酯弹性体/SiO2复合材料的不同制备方法方面进行了尝试,并针对SiO2不同的掺杂方式对聚氨酯树脂材料性能的影响进行了研究,为聚氨酯弹性体性能的优化提供了一条最佳的思路和方法.利用红外分光光度计(IR)、万能电子试验机、动态力学分析仪(DMA)、量热示差扫描仪(DSC)、紫外/可见/近红外分光光度计(UV/VIS/VIR)分别表征了纳米复合树脂材料的结构、力学性能、热稳定性、展色性和干爽性.     

静电纺PU/PANI纳米纤维膜制备及性能研究

以聚苯胺(PANI)和聚氨酯(PU)等为原料,采用静电纺丝技术,成功制备PU/PANI纳米纤维膜。采用SEM扫描电镜研究了PU/PANI配比、纺丝液浓度、挤出速度等对纤维形貌与结构的影响,并研究了其力学性能、过滤性能以及电学性能。结果表明,当PU/PANI质量配比为10∶1,纺丝液质量浓度为8%,挤出速度为6mL/h时,纺丝效果最佳,制得纳米纤维直径分布较为均匀,约为300~500nm。添加一定量的PANI可提高纺丝液电导率,有助于改善静电纺丝效果,降低纳米纤维直径;PU/PANI纳米纤维膜阻抗比纯聚氨酯纳米纤维小2个数量级,具有优良的抗静电性。在32L/min流量下,对0.3μm的粒子,过滤效率达96.0%以上,是一种优异高效抗静电过滤材料。在易燃易爆、安全过滤、特种工况防护服装中具有潜在的应用前景。     

银/聚苯胺纳米复合材料的制备及形成机理

采用反胶束原位复合法制备了银/聚苯胺(Ag/PANI)纳米复合材料,并且探讨了Ag/PANI纳米复合材料的形成机理。通过红外光谱、紫外吸收光谱、X射线衍射、扫描电镜和透射电镜对复合物进行了表征。研究结果表明,Ag/PANI复合材料中Ag为纳米粒子,粒径为50 nm,苯胺自吸附在银纳米粒子表面聚合,形成PANI包覆Ag纳米粒子壳-核结构。Ag纳米粒子在PANI中均匀分散,Ag/PANI复合粒子大部分呈现类球形状的表面形貌,复合粒子粒径较PANI有了明显减小。并提出了Ag/PANI复合材料的形成机制。     

原位悬浮乳液聚合制备聚苯胺/纳米金刚石复合微球及结构表征

利用原位乳液聚合的方法合成得到了聚苯胺(PANI)/纳米金刚石复合微球.用X射线衍射(XRD)、热重-差热(Tg-DTA)、透射电子显微镜(TEM)、粒径分析(PSD)、比表面积分析(BET)、红外光谱(FT-IR)及紫外-可见光谱(UV-Vis)等技术分别对获得的PANI/纳米金刚石复合微球进行了结构、形貌、表面表征.结果表明,在PANI/纳米金刚石复合微球中,纳米金刚石为立方相,复合微球介于10～30nm,粒径分布窄,分散性良好,比表面积可达270m2/g,且具有较好的热稳定性.结构分析证实在PANI/纳米金刚石复合物中,PANI与纳米金刚石之间存在氢键键合机制.     

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 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.     

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.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.