Traditional electrospun nanofibers have a myriad of applications ranging from scaffolds for tissue engineering to components of biosensors and energy harvesting devices. The generally smooth one-dimensional structure of the fibers has stood as a limitation to several interesting novel applications. Control of fiber diameter, porosity and collector geometry will be briefly discussed, as will more traditional methods for controlling fiber morphology and fiber mat architecture. The remainder of the review will focus on new techniques to prepare hierarchically structured fibers. Fibers with hierarchical primary structures including helical, buckled, and beads-on-a- string fibers, as well as fibers with secondary structures, such as nanopores, nanopillars, nanorods, and internally structured fibers and their applications will be discussed. These new materials with helical/buckled morphology are expected to possess unique optical and mechanical properties with possible applications for negative refractive index materials, highly stretchable/high-tensile-strength materials, and components in microelectromechanical devices. Core-shell type fibers enable a much wider variety of materials to be electrospun and are expected to be widely applied in the sensing, drug delivery/controlled release fields, and in the encapsulation of live cells for biological applications. Materials with a hierarchical secondary structure are expected to provide new superhydrophobic and self- cleaning materials.

关键词：纤维；纳米结构；生物检测;生物；能源；

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This chapter discusses the utilization of polybenzoxazine/urethane alloys with fine-tuning properties for ballistic impact composite application. The ballistic impact study of Kevlar? fiber-reinforced polybenzoxazine alloys under the test weapon with standard 124 grains round lead projectile and a copper outer coating (Full Metal Jacket) typically used in the 9-mm handgun at an impact velocity of 426-431 m/s is reported. The polybenzoxazine/urethane alloy matrices at various urethane prepolymer contents were prepared to evaluate the effect of different urethane contents on the thermal, mechanical as well as ballistic resistant properties. Experimental results reveal a synergy in glass transition temperature and some mechanical properties of the alloys at the composition range of 10-30by weight of urethane fraction the thus provide a fascinating group of high temperature polymers with improved flexibility and enhanced a ballistic resistant characteristic.

关键词：聚苯并恶嗪；氨基甲酸乙酯；弹道性能；芳纶；高分子材料

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关键词：粉末冶金；石川分析；复合材料

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This chapter discusses one engineering application of polybenzoxazines as a highly thermally conductive electronic packaging encapsulant. The combination of various useful properties of benzoxazine resins and their resulting polymers has been demonstrated to render a very high thermally conductive polymer composite. Thermal conductivity value as high as 32.5 W/mK in hexagonal boron nitride-filled polybenzoxazine, up to present, remains the highest reported thermal conductivity value in the literature. Other outstanding properties of the resulting composites as an electronic packaging encapsulant are also discussed in this chapter.

关键词：导热复合材料；高填充复合材料；聚苯并恶嗪；H型氮化硼；高分子材料

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Polymer-Electrolyte-Fuel-Cells (PEFCs) are promising candidates for powering vehicles and portable devices using renewable-energy sources. The core of a PEFC is the solid electrolyte membrane that conducts protons from anode to cathode, where water is generated. The conductivity of the membrane, however, depends on the water content of the membrane, which is strongly related to the cell operating conditions. The membrane and other cell components are typically compressed to minimize various contact resistances. Moreover, the swelling of a somewhat constrained membrane in the cell due to the humidity changes generates additional compressive stresses in the membrane. These external stresses are balanced by the internal swelling pressure of the membrane and change the swelling equilibrium. It was shown using a fuel-cell setup that compression could reduce the water content of the membrane or alter the cell resistance. Nevertheless, the effect of compression on the membranes transport properties is yet to be understood, as well as its implications in the structure-functions relationships of the membrane. We previously studied, both experimentally and theoretically, how compression affects the water content of the membrane. However, more information is required the gain a fundamental understanding of the compression effects. In this talk, we present the results of our investigation on the in-situ conductivity of the membrane as a function of humidity and cell compression pressure. Moreover, to better understand the morphology of compressed membrane, small-angle X-ray-scattering (SAXS) experiments were performed. The conductivity data is then analyzed by investigating the size of the water domains of the compressed membrane determined from the SAXS measurements.

关键词：燃料电池；能源；固体电解质；聚合物

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关键词：铕配合物；三苯基氧化膦；白光发射；高分子材料

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The aging infrastructure in the United States puts a huge burden on bridge engineers and officials who strive to ensure public safety and meet community demands. Strengthening existing bridge structures instead of the more expensive replacement alternative has therefore been a more feasible choice in many cases, which led to large research efforts to develop new strengthening methods and explore the use of new materials. Fiber Reinforced Polymer (FRP) composites is considered one of the new materials that continue to grow and gain popularity for structural applications. Successful use of FRP relies on understanding its behavior and being able to confidently assess its properties. Characterizing material properties from random samples is important in order to better understand the behavior of FRP composites and implement them in design codes. Reliable and consistent methods of characterizing the material resistance are essential for the successful employment of any material. There are two popular statistical methods used for finding characteristic values for FRP composites: The first method is recommended by the American Concrete Institute (ACI) in publications produced by Committee 440 (Fiber-Reinforced Polymer Reinforcement), while the other is adopted by the American Society for Testing and Materials (ASTM International) in a standard for Evaluating Material Property Characteristic Values for Polymeric Composites for Civil Engineering Structural Applications, ASTM D7290. In this study, tensile and flexural tests are conducted on different FRP composite materials for the purpose of investigating the differences between these two methods. The experimental results were complemented with simulations of virtual specimens. The experimental and simulation results are then used to estimate the material properties following both characterization methods and to conduct comparisons between both methods.

关键词：桥梁；复合材料；力学性能；纤维增强复合材料

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It is shown by magnetic field dependent ac susceptibility, magnetic force microscopy, and ferromagnetic resonance that exposure of C(sub 60) to fluorine at 160 deg C produces a stable ferromagnetic material with a Curie temperature well above room temperature. The exposure to fluorine is accomplished by decomposing a fluorine rich polymer, trifluorochloroethylene, F(sub 2) (C-CFCl)(sub n) which has C(sub 60) imbedded in it. Based on previous experimental observations and molecular orbital calculations, it is suggested that the ferromagnetism is arising from crystals of C(sub 60)-F.

关键词：铁磁性；铁磁谐振；聚合物；拉曼光谱

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A cassette of uncured composite materials with epoxy resin matrixes was exposed in the stratosphere (40 km altitude) over three days. Temperature variations of -76 to 32.5C and pressure up to 2.1 torr were recorded during flight. An analysis of the chemical structure of the composites showed, that the polymer matrix exposed in the stratosphere becomes crosslinked, while the ground control materials react by way of polymerization reaction of epoxy groups. The space irradiations are considered to be responsible for crosslinking of the uncured polymers exposed in the stratosphere. The composites were cured on Earth after landing. Analysis of the cured composites showed that the polymer matrix remains active under stratospheric conditions. The results can be used for predicting curing processes of polymer composites in a free space environment during an orbital space flight.

关键词：平流层；环氧基复合材料；环氧树脂；固化

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关键词：纤维增强复合材料；聚合物；复合材料；高分子材料

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