Low-surface-free-energy polybenzoxazine/polyacrylonitrile fibers for biononfouling membrane

We blended poly(3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) (PBA) into polyacrylonitrile (PAN) to generate low-surface-free-energy fibers without fluorine and silicon elements for electrospinning. Liquid-state BA at room temperature can be solidified in electrospinning process using PAN as a medium through their miscible behavior. Results indicate that the mixing below 50 wt% BA into PAN matrix for electrospinning has no significant dropping beads, indicated a miscible PAN/BA system. Above 70 wt% BA in PAN solution could not be solidified completely after electrospinning, revealed apparent beaded fibers. The PAN/PBA blend fibers, obtained after curing at 300 °C, generated a superhydrophobicity because of the low-surface-free-energy PBA. In addition, laser scanning confocal microscope (LSCM) measurements were included to determine the relative amount of antibody that adsorbed to these PAN/PBA fibers to examine the biofouling-resistant property. The results showed an obviously decreased protein adsorption with increasing PBA fraction. The correlations between PAN and PBA would provide insight into the designing and developing of low-surface-free-energy fibers without fluorine and silicon elements to improve biofouling-resistant property.     

A Century of Production and Application of Light

THE conquest of dark by means of artificial illumination is considered one of the all-time greatest achievements of mankind. Nothing much can be accomplished in a dark environment. Over one hundred years ago, illuminating gas, carbon arcs, candles, kerosene, and other types of oil lamps were the most widely used artificial light in the world. In 1879, Edison invented the first practical electric lamp. This incandescent lamp marked the beginning of the electrical lighting industry.     

Buckling initiation and displacement dependence in compression of vertically aligned carbon nanotube arrays

Carbon nanotube (CNT) arrays have shown the remarkable ability to react as foam-like structures and exhibit localized buckling coordinated within specific regions. Here, we report on the low-cycle compression of bulk vertically aligned CNT arrays to observe initiation and growth of the buckling as a function of compressive strain. A critical strain is found above which the buckling region length increased and below which it remained at or below the applied strain. As previously observed, the buckling region of the CNT array propagates from the surface where growth occurred, which, in the test specimen, is a free surface and later receives compressive contact by a polished silicon substrate. The results are corroborated with nanoindentation on the surfaces, which indicate a stiffening of the near surface with increasing applied strain. Observation and results of the buckling region nature are important for applications of nanotube arrays as energy absorbing cushions, tunable dampers, thermal contacts, or in sliding contact.     

Solid-state NMR studies on phase behavior and motional mobility in binary blends of polystyrene and poly(cyclohexyl methacrylate)

The phase behavior and motional mobility in binary blends of polystyrene (PS) and poly(cyclohexyl methacrylate) (PCHMA) have been investigated by solid state ¹³C NMR techniques. The blend miscibility has been studied by examining the ¹H spin-relaxation times in the laboratory frame (T₁^H) and in the rotating frame (T_1ρ^H) for the PCHMA/PS blends with various compositions and pure components. The T_1ρ^H results show that PCHMA and PS are intimately mixed at the molecular level within the blends at all compositions. In addition, according to the results of carbon T_1ρ relaxation time measurements, we conclude that mixing is intimate enough to cause a reduction in local chain mobility for PS, but an increase in side chain mobility for PCHMA.     

Equilibrium and kinetic studies of the extraction of chelated copper(II) anions with Aliquat 336

The equilibrium and kinetics of solvent extraction of Cu²⁺ from aqueous solutions containing equimolar EDTA with Aliquat 336 in n‐decanol and kerosene at 298 K were investigated. The concentrations of Cu²⁺ (8–50 mol m^?3), Cl^? (5–60 mol m^?3), and Aliquat 336 (20–100 mol m^?3) were varied. A semi‐empirical model with three parameters was proposed to describe the equilibrium behavior, in which the non‐idealities in both aqueous and organic phases were considered. Over the ranges studied, the model agreed reasonably well with the experimental data (standard deviation, 15%). The forward and backward reaction rate constants were determined as (5.31 ± 0.16)×10^?6 m^9/4 mol^?3/4 s^?1 and (2.62 ± 0.09)×10^?7 s^?1, respectively, at 298 K. An interfacial reaction mechanism was proposed, which revealed that the reaction between the chelated anions and trimeric amine molecules at the interface was rate limiting. The derived rate laws were consistent with the experimental results. © 2002 Society of Chemical Industry     

不同进出风方式对旋风筒主要性能参数的影响

针对旋风筒内存在的局部二次涡流,对传统的旋风筒做了几种形式的改进,通过冷态模型试验,研究了不同进出风方式对旋风筒的压力损失、分离效率和切割粒径等主要性能参数的影响,为开发新型旋风筒提供了参考。     

聚甲醛生产、消费及技术进展

介绍了国内外聚甲醛生产及消费情况 ,对均聚法和共聚法生产聚甲醛工艺技术进行了比较。认为应加快发展聚甲醛产品 ,以适应汽车、电子等新兴行业对聚甲醛工程塑料的要求     

Morphological,mechanical, and thermal characterization of biopolymer composites based on polylactide and nanographite platelets

This work focuses on development and optimization of polylactide (PLA) and nanographite platelets (NGP) based composites to display possible superior mechanical and improved thermal stability. Melt blending and dry mixing methods of fabrication were employed at temperature of 180°C. Different Loading fractions of NGP were incorporated into polymer matrix. Morphological evaluation techniques such as XRD and TEM were applied to determine the degree of dispersion of NGPs into PLA matrix. Mechanical properties were evaluated and correlated to structural morphologies of PLA/NGP composites. Thermal properties of composites were studied to examine possible changes in T_g, T_c, T_m, and percentage crystallinity of these composites. The effect of mixing was also explored through double extrusion of some samples. It was concluded that composites containing 3 wt% NGP showed optimum mechanical performance without any significant changes in the thermal characteristics. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Fabrication and Thermal Dissipation Properties of Carbon Nanofibers Derived from Electrospun Poly(Amic Acid) Carboxylate Salt Nanofibers

Polyimides (PIs) possess excellent mechanical properties, thermal stability, and chemical resistance and can be converted to carbon materials by thermal carbonization. The preparation of carbon nanomaterials by carbonizing PI‐based nanomaterials, however, has been less studied. In this work, the fabrication of PI nanofibers is investigated using electrospinning and their transformation to carbon nanofibers. Poly(amic acid) carboxylate salts (PAASs) solutions are first electrospun to form PAAS nanofibers. After the imidization and carbonization processes, PI and carbon nanofibers can then be obtained, respectively. The Raman spectra reveal that the carbon nanofibers are partially graphitized by the carbonization process. The diameters of the PI nanofibers are observed to be smaller than those of the PAAS nanofibers because of the formation of the more densely packed structures after the imidization processes; the diameters of the carbon nanofibers remain similar to those of the PI nanofibers after the carbonization process. The thermal dissipation behaviors of the PI and carbon nanofibers are also examined. The infrared images indicate that the transfer rates of thermal energy for the carbon nanofibers are higher than those for the PI nanofibers, due to the better thermal conductivity of carbon caused by the covalent sp² bonding between carbon atoms.     

Formation polarity dependent improved resistive switching memory characteristics using nanoscale (1.3 nm) core-shell IrOx nano-dots

ABSTRACT: Improved resistive switching memory characteristics by controlling the formation polarity in an IrOx/Al2O3/IrOx-ND/Al2O3/WOx/W structure have been investigated. High density of 1 × 1013/cm2 and small size of 1.3 nm in diameter of the IrOx nano-dots (NDs) have been observed by high-resolution transmission electron microscopy. The IrOx-NDs, Al2O3, and WOx layers are confirmed by X-ray photo-electron spectroscopy. Capacitance-voltage hysteresis characteristics show higher charge-trapping density in the IrOx-ND memory as compared to the pure Al2O3 devices. This suggests that the IrOx-ND device has more defect sites than that of the pure Al2O3 devices. Stable resistive switching characteristics under positive formation polarity on the IrOx electrode are observed, and the conducting filament is controlled by oxygen ion migration toward the Al2O3/IrOx top electrode interface. The switching mechanism is explained schematically based on our resistive switching parameters. The resistive switching random access memory (ReRAM) devices under positive formation polarity have an applicable resistance ratio of > 10 after extrapolation of 10 years data retention at 85°C and a long read endurance of 105 cycles. A large memory size of > 60 Tbit/sq in. can be realized in future for ReRAM device application. This study is not only important for improving the resistive switching memory performance but also help design other nanoscale high-density nonvolatile memory in future.