Investigation into effect of the graphene oxide addition on the mechanical properties of the fiber metal laminates

Fiber Metal Laminates (FMLs) is developing very fast with the both features of resin-based composite and metal and its property can be improved by mixing nano-scale particles as FMLs-Nano. Based on the different mixing volume fractions, this paper investigated the effect of Graphene Oxide (GO) on the mechanical properties of the FMLs with carbon fiber used, including tensile, flexural and interface shear behaviors. The interface strengthening mechanism of GO as significant filler for enhancing the carbon woven fabric based FMLs' was explored. To encourage the application range of FMLs-Nano in the fields of aircraft, aerospace and automotive etc. to form the complicated components. It was observed that the FMLs with GO (FMLs-GO) has the better tensile performance than the FMLs without GO and the Young's modulus and tensile strength of the FMLs-GO are increased by 13.5% and 11.7%, respectively. Especially, the flexural and interface shear strength can be increased up to 134.0% and 150.4% compared to the pure FMLs and the improvement mechanism was investigated mechanically and observed with scanned micrograph. This paper also provides a fundamental reference for improving the interfacial performance of different layers of FMLs-GO by using the normal preparation condition.     

Selection of mandrel wrap mode filters for optical fiber loss measurements

A selection criterion for mode filters based on far-field patterns is developed. The criterion is used to select a mandrel wrap filter for 50 μm core diameter, 125 μm outside diameter fibers with δ=1.1%. When cut-back loss measurements were made using the mandrel wrap chosen in this way, loss scaled with length to within ± 0.05 dB/km in three 2-km fibers.     

Electrospun polymer nanofibers: Mechanical and thermodynamic perspectives

This article reviews and discusses some open problems concerning polymer materials of reduced sizes and dimensions. Such objects exhibit exceptional physical properties when compared with their macroscopic counterparts. More specifically, abrupt increases in polymer nanofiber elastic modulus have been observed when diameters drop below a certain value. In addition, temperature dependence of elastic modulus is highly influenced by fiber diameter. Mechanical (macroscopic) analyses have failed to provide satisfactory explanations for the mechanisms ruling such features, calling for detailed microscopic examination of the systems in question. A hypothesis bridging the current knowledge gaps is presented. The key element of this hypothesis is based on confinement of the supermolecular microstructure of polymer nanofibers and its dominant role in the deformation process. This suggestion challenges the commonly held view suggesting that surface effects are the most significant parameters impacting mechanical and thermodynamic nanofiber behaviors. The review will focus on the mechanical and thermodynamic properties of electrospun polymer nanofibers, selected as representatives of nanoscale polymer objects. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

In situ synthesis of ZnO nanocrystal/PET hybrid nanofibers via electrospinning

Hybrid nanofibers of ZnO precursors/PET were fabricated by electrospinning a nonaqueous poly(ethylene terephthalate) (PET) solution containing zinc acetate dihydrate. Scanning electron microscopy images showed that the as prepared nanofibers had smooth and uniform surfaces, and the diameter was decreased with increasing zinc acetate dihydrate content and reducing PET concentration. After the treatment by a mild process of immersing the fibers in ammonia‐ethanol mixtures (pH ≈ 9–11), the surface of the nanofibers became rough during the formation of ZnO nanocrystals in the fibers. High resolution transmission electron microscopy images showed that the mean particle size became smaller with increasing diameter of the polymer fibers and decreasing content of ZnO. Fourier transform infrared spectra confirmed the ZnO formation in the hybrid nanofibers. X‐ray diffractometry patterns indicated that ZnO had the Wurtzite structure. The formation and growth of ZnO nanocrystals in the nanofiber matrices was also influenced by the various other parameters, that is, the pH value of the reaction solution, the content of zinc acetate dihydrate within the fibers, the reaction time and temperature. Photoluminescence spectra under excitation at 300 nm revealed a broad and intense ultraviolet emission. The UV‐visible diffuse reflectance spectra demonstrated the blue shift in the absorbance curve, which was ascribed to the quantum confinement effects of ZnO nanoparticles in the hybrid materials. These hybrid nanofibers can potentially be used in light emitters, chemical sensors, photo‐catalysts and solar cells. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1360–1368, 2011     

Polysaccharide-Based Drug Delivery Systems for the Treatment of Periodontitis

Periodontal diseases are worldwide health problems that negatively affect the lifestyle of many people. The long-term effect of the classical treatments, including the mechanical removal of bacterial plaque, is not effective enough, causing the scientific world to find other alternatives. Polymer–drug systems, which have different forms of presentation, chosen depending on the nature of the disease, the mode of administration, the type of polymer used, etc., have become very promising. Hydrogels, for example (in the form of films, micro-/nanoparticles, implants, inserts, etc.), contain the drug included, encapsulated, or adsorbed on the surface. Biologically active compounds can also be associated directly with the polymer chains by covalent or ionic binding (polymer–drug conjugates). Not just any polymer can be used as a support for drug combination due to the constraints imposed by the fact that the system works inside the body. Biopolymers, especially polysaccharides and their derivatives and to a lesser extent proteins, are preferred for this purpose. This paper aims to review in detail the biopolymer–drug systems that have emerged in the last decade as alternatives to the classical treatment of periodontal disease.     

The Preparation of Slag Fiber and Its Application in Microwave Absorption

In this research, the slag fibers coming from water‐quenched slags by using thermal plasma technology were successfully prepared and introduced into epoxy resin to be microwave absorber. The fiber‐blowing equipment for manufacturing slag fibers through controlling the nozzle angle and vertical distance from the nozzle to the melt outlet was also studied. The spectroscopic characterization of the formation processes of slag fiber was studied by using X‐ray diffraction (XRD), inductively‐coupled plasma (ICP), differential thermal analysis (DTA) and scanning electron microscopy (SEM). Microwave absorbing properties of the slag fibers and thermal plastic resin were investigated by measuring reflection loss in the 2–18 and 18–40 GHz microwave frequency range using the free space method. It was found that the composite specimens of slag fiber and thermal plastic resin had the best microwave absorption due to the reflection losses between from −4 to −8 dB and from −11 to −17 dB at frequencies between 2–18 and 18–40 GHz.     

偶联剂在改善天然植物纤维/塑料界面相容性的应用

天然植物纤维界面特性十分复杂,其表面表现出很强的化学极性,导致天然植物纤维与塑料基材界面间相容性差,粘结力小,从而影响了植物纤维/塑料复合材料的冲击强度、拉伸强度等物理力学性能。因此,天然植物纤维/塑料界面相容性是决定复合材料性能的关键问题。本文概述了改善天然植物纤维/塑料界面相容性的常用偶联剂的特点和应用,偶联机理以及研究、应用现状,展望了应用于天然植物纤维增强塑料复合材料的偶联剂未来的研究方向。     

PBG-PCF基模特性全矢量平面波多极方法联合数值研究

用全矢量平面波方法与多极方法联合数值研究六重对称带隙型光子晶体光纤的基模特性.通过全矢量平面波方法可确定组成PBG-PCF的二维光子晶体的带隙,基模(束缚模)存在其频率要落在带隙内且须在k0a=βa的直线附近上部区域,在带隙外形成辐射(泄漏模).把频率作为输入变量用多极方法计算,数据导出用MATLAB数学软件作出模场分布图,结果发现,不是所有基模可能存在的区域都有基模存在,为带隙型光子晶体光纤的基模寻找提供一种可行的方法.     

基于四波混频效应的窄带太赫兹波源

采用频率差在太赫兹范围的双波长激光器进行泵浦,利用光纤的四波混频效应,得到结构紧凑、频率可调的窄带太赫兹波源。为减小光纤材料对太赫兹波的吸收,采用了表面发射机制。从耦合波理论出发,详细分析了保偏光纤中的四波混频过程,得到了太赫兹波输出功率的解析表达式,并讨论了实现相位匹配的条件。结果表明,太赫兹波功率与泵浦光功率和光纤长度成正比,与太赫兹波长的3次方成反比。当泵浦光峰值功率为1 kW,在6 THz处得到的太赫兹波峰值功率达350 mW,功率转换效率约为0.01%。通过合理设置泵浦波长,可以实现太赫兹辐射在3~8 THz范围内连续调谐。该方案提供了一种新型的高功率、紧凑型的窄带太赫兹辐射源。     

基于谐振耦合现象的三芯光子晶体光纤带通滤波器

设计了一种三芯光子晶体光纤带通滤波器结构.利用纤芯间的谐振耦合,实现了滤波.当3个纤芯基模模式有效折射率在同一频率点实现匹配时,将产生谐振现象.通过合理选取光纤结构参数,可以使3个模式满足谐振条件.由于3个纤芯基模只在工作波长处实现有效折射率的匹配,因而纤芯间发生波长的选择性耦合.应用全矢量光束传播法(BPM)分析了这种光纤带通滤波器的性能.结果表明:在1.55 μm工作波长上,光纤耦合长度为22.8 mm;在损耗低于-3 dB前提下,通带带宽为8.9 nm.