光子晶体光纤的多模色散特征

采用有效折射率模型对光子晶体光纤的多模色散参数进行了数值计算,给出了不同结构光子晶体光纤的多模色散系数随波长的变化关系,并对计算结果作出了合理的物理解释.     

Characteristics of wet‐spun and thermally treated poly acrylonitrile fibers

The performance of carbon fibers depends on the quality of the precursor and the conditions of the thermal treatment. In detail, for a PAN precursor fiber the viscosity of a spinning dope and the draw ratio during the spinning process needs to be considered. Through wet spinning, different types of PAN precursor fibers with defined spinning parameters, including solid content, solvent content in a bath, and especially draw ratio resulting in defined cross section diameters, were fabricated and analyzed with tensile tests, density investigations, SEM, TGA‐MS, FTIR, and XRD. The results show that the mechanical properties of the fibers correlate to crystallinity. The cross section diameter is strongly related to the morphology of the fibers after thermal treatment. By extending the postdrawing of PAN fibers high tenacities were obtained at the cost of the cross section shape. In addition, TGA measurements reveal trapped residues of the wet spinning process as well as show several chemical reactions takes place at the same time at different temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43698.     

Thermal,mechanical, and corrosion resistance properties of vinyl ester/clay nanocomposites for the matrix of carbon fiber‐reinforced composites exposed to electron beam

Vinyl ester/clay nanocomposites with 1, 3, and 5% nanoclay contents were prepared. X‐ray diffractography patterns and Scanning Electron micrographs showed that nanocomposites with the exfoliated structure were formed. Thermogravimetric analysis, water absorption test, and Tafel polarization method, respectively, revealed the improvements in thermal resistance, water barrier properties, and corrosion resistance properties of the samples with an increase in the amount of the incorporated nanoclay. Tensile tests showed that nanoclay also enhanced the mechanical properties of the polymer, so that the tensile strength of the samples with 5% nanoclay was more than 3 times higher than tensile strength of pure vinyl ester samples. Overall, the best properties were observed for the samples containing 5% nanoclay. Pure vinyl ester and nanocomposite with 5% nanoclay content were exposed to the electron beam radiation and their mechanical properties improved up to 500 kGy irradiation dose. Finally, pure vinyl ester and vinyl ester/nanoclay (5%) matrixes were reinforced with carbon fiber and the effect of electron beam irradiation on their mechanical properties was examined. The tensile strength and the modulus of the samples initially increased after exposure to the radiation doses up to 500 kGy and then a decrease was observed as the irradiation dose rose to 1000 kGy. Moreover, nanoclay moderated the effect of the irradiation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42393.     

Relationships Between Birefringence of Constituent Fibers and Properties of Thermally Bonded Nonwovens

Summary: Three‐dimensional nonwoven fabrics have been produced using a newly developed air‐laid web forming and through‐air thermal‐bonding process directly from commercial PP/polyester (sheath/core) bi‐component staple fibers. Following the previous study on the morphology and structure of constituent fibers, this paper reports the breaking force and abrasion resistance of the fabrics. Results indicate that the relationships between both the breaking strength and abrasion resistance of the samples, and the thermal‐bonding process conditions are similar to each other. The appropriate thermal‐bonding temperature and dwell time are critical for achieving fabrics with high breaking strength and abrasion resistance. Such relationships are inconsistent with those between the tensile strength of the constituent fiber reflected by the birefringence and the thermal‐bonding process conditions. The birefringence of the constituent fiber appears to decrease with increasing thermal‐bonding temperature and dwell time. These results provide evidence that both the breaking force and abrasion resistance for the thermally bonded nonwoven fabrics are governed not only by the mechanical properties of constituent fibers, but also by the bonding properties between the fibers.

Abrasion mass loss and breaking force of fabric and birefringence of constituent fiber for the thermally bonded nonwoven samples as functions of the dwell time.     

有机耐高温纤维的性能和应用

介绍了有机耐高温纤维的品种及其性能和应用,并对各耐高温纤维的性能进行了比较。     

Hierarchical mullite structures and their heat-insulation and compression–resilience properties

Near-net-shaped hierarchical structure-adjustable short mullite fibers/mullite whiskers frameworks (MF/MW frameworks) were prepared by slurry-filtration and heat-treating method. The main structure of MF/MW framework was constituted by lap-jointed mullite fibers. Every single fiber in the framework was densely covered by mullite whiskers which formed through fluorine-catalyzed gas-phase reaction, and the fibers actually served as curved substrates for the mullite whiskers' growth. The lap-jointing points of the fibers were served by movable intersected mullite whiskers. Moreover, the microstructure of the frameworks could be adjusted by tailoring the raw materials mass ratio. The volume densities, the apparent porosities and the thermal conductivities of the MF/MW frameworks in different raw materials mass ratios were 0.459–0.487 g/cm³, 79.7–82.8% and 0.1356–0.1965 W/k m, respectively. The compression–resilience property of the samples was tested under 0.4 MPa at room temperature. The compression ratio and resilience ratio of the MF/MW frameworks in different raw materials mass ratios were 1.63–2.25% and 92.67–98.16%, respectively. The MF/MW frameworks with advanced thermal and mechanical properties were considered to be promising high-temperature heat-insulation material.     

Recent studies on electrospinning preparation of patterned,core–shell,and aligned scaffolds

Electrospinning is one of the most important ways to prepare continuous, high porosity, large specific surface area, and uniform diameter micro‐ and nanoscale fibers. So, it has been widely used in the preparation of micro/nano‐sized polymer scaffolds for tissue engineering in recent years. In addition to the versatility in material selection and the processing variables, electrospinning also provides a lot of methods to regulate fiber structure and scaffolds morphology. For example, the near‐field electrospinning can provide a method to solve the problem of uncontrollable fiber path; the melt electrospinning eliminates the risk of solvent residue in the construct; the addition of different auxiliary electrodes can make the fiber patterned. This review introduces the underlying principle and characteristics of above electrospinning applied in biomedicine. Herein, we highlight a comprehensive understanding of the technical aspect of this technology for versatile fibers with patterned, core–shell and aligned morphology. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46570.     

Effect of treatment of activated carbon fiber cloth electrodes with cold plasma upon performance of electric double-layer capacitors

Charge/discharge behavior of electric double-layer capacitors composed of activated carbon fiber cloth (ACFC) electrodes and an organic electrolyte was investigated. The modification of the ACFC electrodes was performed using cold plasma generated in argon-oxygen atmosphere. The effect of the cold plasma treatment of the ACPC electrodes on the capacitor performance was discussed on the basis of the physical and chemical properties of the ACFC surface such as pore radius distribution and surface atom concentration.     

Fe2+/UV催化臭氧法降解腈纶废水

 研究了Fe²⁺/UV催化臭氧对腈纶废水的降解特性,分析了[Fe²⁺]/[O₃]质量浓度比、气相臭氧质量浓度和光强各因素对Fe²⁺/UV催化臭氧降解性能的影响规律,讨论了Fe²⁺/UV催化臭氧工艺光催化反应动力学特征,并利用红外光谱分析法表征了废水中有机物基团的变化。结果表明,当[Fe²⁺]/[O₃]质量浓度比为3.2~3.8、气相臭氧质量浓度为20～30mg/L和光量子流密度为8.62×10-12 Einstein时,催化效果较好。Fe²⁺/UV催化臭氧工艺降解腈纶废水符合类一级动力学反应,初始COD值在320~400 mg/L范围内,一级反应速率常数为0.01518~0.01762 min-1。温度对动力学影响具有双重性,温度为25~30℃反应最快。经Fe²⁺/UV催化臭氧降解后,腈纶废水中有机基团被有效降解。