Preparation of polyaniline–Fe2O3 composite and its anticorrosion performance

Polyaniline–Fe₂O₃ composites were chemically prepared by oxidative polymerization of aniline in phosphoric acid medium with ammonium persulphate as oxidant. Different ratios of aniline–Fe₂O₃ were taken to prepare polyaniline–Fe₂O₃ composites, i.e. 1:2, 1:1, 2:1. The composites were characterized by FTIR, XRD and SEM. Using the prepared composites, primer paints with acrylic binder were prepared and coated on the steel samples. The corrosion protection ability of the coating was found out by EIS method in 3% NaCl solution. It has been found that the coating with composite of 1:1 ratio of aniline:Fe₂O₃ is found to offer higher protection than the coating with other ratios and plain Fe₂O₃.     

烧结NdFeB表面碳纳米管/环氧树脂复合涂层的性能

采用阴极电泳沉积技术在烧结钕铁硼磁体表面制备了碳纳米管/环氧树脂复合涂层,利用扫描电子显微镜、拉曼光谱仪、电化学工作站、稀硫酸浸泡试验、盐雾试验、PCT试验、拉伸试验、划线格试验和铅笔硬度计分析了涂层的表面形貌、耐腐蚀性能和力学性能。结果表明,复合涂层表面光滑平整,无宏观缺陷,碳纳米管均匀弥散地镶嵌在环氧树脂涂层中;碳纳米管/环氧树脂复合涂层能有效提高烧结钕铁硼永磁材料的耐腐蚀性能;而且,碳纳米管有效地提高了涂层的力学性能。     

Combined effects of silica filler and its interface in epoxy resin

In this paper, mechanical properties of silica-filled epoxy resin are tested. The tests show that at elevated temperatures, the material’s properties (e.g. yield stress, flow stress, etc.) vary immonotonically with filler volume fraction. Nano-indentation test results suggest that an interface region, stronger than the matrix, is formed in the materials. The formation of the interface has positive effects on the yield strengths of materials. The addition of particles in the matrix produces a large disturbance in stress distribution, leading to stress concentration in the matrix. The stress concentration has negative effects on the yield strengths of materials. The calculation demonstrates that the maximum stress in samples varies immonotonically with particulate concentration. So, the immonotonic variation of mechanical behavior of materials may be rooted in the contradictory effects of the interface region and the stress concentration caused by particulate addition.     

Carbon nanotube/epoxy resin composite: Correlation between state of nanotube dispersion and Zener tunneling parameters

Carbon nanotube/epoxy resin composites with different levels of nanotube dispersion in the polymer matrix were prepared. The effects of nanotube dispersion on tunneling conductive behavior of such composites were investigated. The composites with homogeneous nanotube dispersion were found to exhibit larger static electrical conductivity and smaller percolation threshold than those with poorer nanotube dispersion. In addition, uniformly dispersed nanotubes induced strong Zener effect under the application of an electric field. The static conductivity and Zener tunneling parameters were shown to be good indicators for the state of nanotube dispersion.     

The effects of dopant on morphology formation in polyaniline graphite nanoplatelet composite

In this study, a nanocomposite (SELA-PANi/GNP) consisting of selenious acid (SELA) doped polyaniline (PANi) and graphite nanoplatelet (GNP) was prepared, and its structure and properties – in particular, morphology formation, as well as interaction between the two phases – were investigated using scanning electron microscopy (SEM), UV–vis spectroscopy, FTIR spectroscopy, X-ray diffraction, and electrical conductivity measurement. A PANi/GNP nanocomposite prepared in aqueous HCl solution (HCl-PANi/GNP) was also prepared for comparison with SELA-PANi/GNP. The results reveal that the dopant plays an important role in morphology formation in PANi/GNP nanocomposites. When HCl was used as the dopant, PANi coated GNPs were formed and no phase separation between PANi and GNP was seen. In contrast, when SELA was used as the dopant, the morphology of PANi remained unchanged in the composite, owing to the formation of rod or sphere micelle PANi structure during in situ polymerization; no interaction was observed between the two phases. The crystalline structure of PANi was not affected by the incorporation of GNP. The electrical conductivity of PANi/GNP increased with increasing GNP content, because of the electrical bridge effect of GNP in the PANi matrix.     

一种具有宽频吸波性能的环氧树脂基夹层复合板设计与制备

本文设计和制备了一种在C波段上具有宽频吸波性能的夹层复合材料,并用同轴电缆法和矢量网络分析仪分析了复合材料板的电磁参数和反射率。复合材料板厚度5mm,板表层与底层为玻璃纤维/环氧树脂复合材料,以“Fe50Ni50粉体/丁基橡胶纳米复合材料”为中间夹层。采用液相还原法制备了粒径约为100nm的球形Fe50Ni50粉末,采用二步共混法制备了Fe50Ni50 /IIR复合材料。研究表明, Fe50Ni50粉体/IIR纳米复合材料在2~18GHz频带上以磁损耗为主。表层与夹层的匹配是获得宽频吸波特性的关键,可以通过调整表层与夹层的厚度获得良好的吸波性能。当复合材料板厚度为5mm、夹层厚度为2mm时,板的R≤-10dB的吸波频带为5.6GHz~7.6GHz和16.8GHz~18GHz,吸波带宽达到3.2GHz,该材料在C波段吸波带宽达到2GHz,取得了突破。     

Manufacturing Al/Mg composite materials

The manufacturing of innovative lightweight materials and their further processing by forming allows functional dimensioning of components in addition to lightweight design. Accordingly, workpieces can be produced that have locally differing component properties. The new lateral extrusion process of composites produces near net shape lightweight composites. This process application is particularly useful when producing corrosion-resistant Al/Mg composites since it facilitates combining the favorable strength/weight ratio of magnesium with the favorable corrosion behavior of aluminum. The composite interface area is of specific significance in this respect. The presented method initiates diffusion processes with phase reformation to obtain a firmly-bonded metal joint.     

Synthesis of conductive adhesives based on epoxy resin and polyaniline.DBSA using the in situ polymerization and physical mixing procedures

Electrically conductive adhesives based on epoxy-anhydride system containing polyaniline (PAni) doped with dodecylbenzenesulfonic acid (DBSA) have been successfully developed and characterized. The blends were prepared by physical mixing and by in situ polymerization of aniline within epoxy matrix. The in situ polymerization procedure contributes for the formation of a conducting pathway with lower amount of PAni.DBSA. A conductivity as low as 10^?3 S cm^?1 with 12 wt% of PAni and excellent adhesion properties were achieved with these systems. The microstructure of the conductive adhesives was studied by means of scanning electron microscopy (SEM). In the case of blends prepared by in situ polymerization, PAni.DBSA is dispersed within the epoxy matrix in the form of microtubules. Dielectrical properties as a function of frequency and temperature have also indicated a great interaction between polyaniline and epoxy matrix by in situ polymerization procedure.     

Change in morphology of polyaniline/graphite composite: A fractal dimension approach

Polyaniline/graphite composites (PANi/G) with different graphite particle sizes were deposited on a platinum electrode by means of cyclic voltammetry. The surface morphology of PANi/G composites were studied by using the scanning electron microscopy (SEM) and the fractal dimension concept. This work presents the utilization of the cyclic voltammetry and electrochemical impedance spectroscopy to determine the fractal dimension. The results obtained from both these methods are in good agreement indicating the reliability of the estimated fractal dimension (D_f).     

Degradation of basalt fibre and glass fibre/epoxy resin composites in seawater

Epoxy resins reinforced, respectively, by basalt fibres and glass fibres were treated with a seawater solution for different periods of time. Both the mass gain ratio and the strength maintenance ratio of the composites were examined after the treatment. The fracture surfaces were characterized using scanning electron microscopy. The tensile and bending strengths of the seawater treated samples showed a decreasing trend with treating time. In general, the anti-seawater corrosion property of the basalt fibre reinforced composites was almost the same as that of the glass fibre reinforced ones. Based on the experimental results, possible corrosion mechanisms were explored, indicating that an effective lowering of the Fe²⁺ content in the basalt fibre could lead to a higher stability for the basalt fibre reinforced composites in a seawater environment.     

烧结温度对环氧树脂/竹基木陶瓷性能的影响

为了了解烧结温度对木陶瓷基本性能的影响,将浸渍了环氧树脂的竹粉和竹纤维压制成复合板材,在不同的温度下烧结而得到环氧树脂/竹基木陶瓷。采用X射线衍射仪（XRD）、扫描电镜（SEM）等测试设备研究了烧结温对其物相变化、微观结构和力学性能等方面的影响。结果表明：竹基木陶瓷是由石墨微晶所构成的多孔碳素材料,较高的烧结温度能够改善其石墨化程度,但不能完全石墨化;在微观形态上表现为三维网络结构,同时部分保存了竹材的天然结构特征;其显气孔率随着烧结温度的增加而增加,表观密度则显示出相反的特征;抗弯和抗压强度在低温处随烧结温度的提高而增加,但在1200℃之后有降低的趋势。同时,摩擦系数则随着烧结温度的提高而明显下降。当烧结温度为1200℃左右时,环氧树脂-竹基木陶瓷具有较好的性能。     

Preparation of polyaniline/2-dimensional hexagonal mesoporous carbon composite for supercapacitor

2-D hexagonal mesoporous carbon is combined with polyaniline by a simple chemical oxidation polymerization. As-prepared samples are characterized via Fourier transform infrared spectrum, nitrogen sorption analysis and transmission electron microscopy. The experimental results demonstrate that polyaniline is linked with the functional groups on the surface of mesoporous carbon via the chemical bonds. The electrochemical tests reveal mesoporous carbon and polyaniline have a strong synergetic effect, which not only enhances the stability of polyaniline, but also increases the capacitance and energy density of the composite materials. A wide potential window of 1.1 V for the composite is obtained in aqueous electrolyte. The specific capacitance and specific energy density are as high as 470 F/g and 76.4 Wh/kg, respectively.     

碳包覆镍纳米颗粒/聚苯胺复合材料的制备及电磁性能

以纤维素为炭前躯体,硝酸镍为金属源,采用还原炭化法制备出碳包覆Ni纳米颗粒(Ni@C)。进一步采用原位聚合法合成出Ni@C/聚苯胺(PANI)复合材料。TEM分析表明:Ni@C粒度分布均匀,呈核壳结构。采用IR光谱、SEM、XRD对复合材料和形态和结构进行分析;考察了Ni@C的含量对Ni@C/PANI复合材料电导率的影响。采用波导法在8.2-12.4 GHz波段范围对Ni@C和Ni@C/PANI复合材料进行电磁参数进行测试分析,复合材料的电损耗角正切值可达到0.65,磁损耗角正切值可达0.15,所制备Ni@C/PANI具有较高的电磁损耗角正切值,结果表明其吸波性能较好。     

金属/金刚石复合磨料在树脂磨具中的应用

为改善砂轮磨削钢轨的性能,通过热压烧结再固化的方法制备超硬复合磨料树脂磨具试验样条,考察不同种类的复合磨料对样条抗弯强度、抗冲击强度及磨具磨耗比的影响,并用电镜观察磨削后磨具及钢轨对磨件的形貌,表征磨削表面质量.结果显示:超硬磨料与金属结合剂造粒后,抗弯强度、抗冲击强度、磨耗比均得到明显提高,最大分别提高50％、近2倍...     

Solvent co-assisted ultrasound technique for the preparation of silver nanowire/polyaniline composite

Silver wire/polyaniline (Ag⁰/PAni) composite was prepared by the sonochemical solvent assisted method. This composite was obtained after sonicating a silver nitrate (AgNO₃) and anilinium nitrate aqueous solution in the presence of isopropyl alcohol. The presence of the alcohol decreases the polymerization kinetics of the conducting polymer and allows a more stable dispersion of the polymer composite to be obtained. As a matter of fact, precipitation of the polymer occurs when the reaction takes place in the absence of isopropyl alcohol. Scanning electron microscopy revealed that isopropyl alcohol has a remarkable effect on the growth and the morphological structure of reduced silver. Also, the reaction time is an important parameter which allows us to obtain silver wires with a mean diameter of 120 nm and a medium length of 4 μm instead of the spherical particles ordinarily obtained by synthesis without the alcohol. Additionally, we observed that bigger silver wires with a mean diameter of 1.5 μm and a length of 85 μm were obtained if the reaction medium was left to rest in a dark place after the sonication process ended. X-ray diffraction (XRD) and UV–vis absorption spectroscopy indicate that the reduced silver is highly crystalline and the polymer obtained is PAni in the emeraldine salt form.     

碳化物/钢基复合材料原料球磨效果及其电子理论分析

对碳化钛、碳化钨/钢基复合材料原料粉体进行了球磨试验和相应粒度变化等的SEM等分析.结果表明:作为硬质相的WC、TiC球磨细化效果最佳;作为基体材料的体心立方金属球磨效果较好(且Mo＞Cr＞Fe),面心立方镍的球磨效果较差,石墨仅初期球磨效果好.运用固体与分子经验电子理论,结合原料单质的键性质和晶体结构特征分析了实验结果,并依据计算得到的价电子结构参数(nA值与η值及键络均衡性)剖析了以上复合材料原料单质球磨行为的差异.     

纤维/树脂/铝合金叠层复合材料的显微组织与阻尼性能

采用热压固化成形工艺成功制备了纤维／树脂／铝合金叠层复合材料。采用扫描电镜分析了铝合金表面处理工艺对叠层复合材料界面显微组织的影响。结果表明：该种复合材料不仅具有较高的强度和良好的成形加工性，而且抗震性能好，其振动衰减系数较基体铝合金有较大程度的提高。     

碳纤维复合材料电子质子综合辐照损伤研究

研究了电子、质子综合辐照条件下碳纤维/环氧复合材料力学性能、质量损失率等性能的变化规律,并采用FT-IR、XPS等对空间环境作用前后的材料进行了分析和表征。结果表明,随辐照注量增加复合材料层间剪切强度呈先上升后下降趋势,质量损失则先快速升高,在2.0×1016cm-2辐照注量后趋于平缓。     

In-situ electrochemical polymerization of multi-walled carbon nanotube/polyaniline composite films for electrochemical supercapacitors

Multi-walled carbon nanotube (MWCNT)/polyaniline (PANI) composite films were prepared by in-situ electrochemical polymerization of an aniline solution containing different MWCNT contents. The supercapacitive behaviors of these films were investigated with cyclic voltammetry (CV), charge–discharge tests, and ac impedance spectroscopy. The results revealed that the MWCNT/PANI films show much higher specific capacitance (SC), better power characteristic, better cyclic stability, and more promising for applications in supercapacitors than a pure PANI film electrode. The highest specific capacitance value of 500 F g^?1 was obtained for the MWCNT/PANI composite film containing MWCNT of 0.8 wt.%. The improvement mechanisms of the capacitance of the composites are also discussed in detail.