Nano Engineering and Materials Technologies II

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Authors: Abdulhamid Al-Abduljabbar
Abstract: Polymer-clay nanocomposites (PCNC), are characterized by the high ratio of surface area to volume of the clay nanoparticles which are in the form of clay platelets with very high aspect ratio. This feature provides superior gas barrier properties at very low volume fraction of the nanofiller. Clay platelets introduce discontinuity to flows through the bulk polymer matrix material. The extent of this improvement depends on the success of separation of clay layers during processing which would produce single-layer particles (exfoliation) or several-layer particles (intercalation) through the bulk polymer matrix. This paper discusses the common permeability models used to capture the effects of the clay nanofillers in PCNC. Since these models assume a state of full exfoliation of clay platelets; that is a single phase of the nanofiller, they fall short of representing the actual state as evidenced by experimental works, which confirm the presence of both the intercalated phase and the exfoliated phase. A model that incorporates clay inclusions with different sizes (different thicknesses) is proposed and its implications are assessed.
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Authors: Farooq Ahmed, Umair Ahmed Qureshi, Zeeshan Khatri
Abstract: We report herein, the synthesis of colorful nanofibers by electrospinning and dyeing with various class of dyestuff. Results revealed that dyes impart better color yield with the acceptable colorimetric values, color yield and color fastness. Morphology of nanofibers showed smooth surface of the dyed nanofibers under SEM. Cellulose nanofibers in particular, were prepared using precursor cellulose acetate and then converted into cellulose under alkaline treatment. Results revealed that dyes impart better color yield with the adequate color yield (KS) and color fastness. Morphology of nanofibers showed smooth nanofibers after dyeing under SEM. Based results obtained, the colorful nanofiber can be a better choice for advance apparel applications.
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Authors: Masaki Kogiso, Wu Xiao Ding, Mitsutoshi Masuda
Abstract: An organic nanocapsule was obtained by mixing zinc acetate powder into a peptide lipid dispersion in ethanol. The nanocapsule was mass-produced at a scale of over 100 g L–1 within 1 h. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that a zinc-peptide lipid complex was formed within 15 min, which subsequently transformed into a nanocapsule as a result of changes in the hydrogen bonding networks between the peptides. A variety of organic dyes could be encapsulated by simply adding them during the nanocapsule formation. We also confirmed their high stabilities in organic solvents, water-responsive morphological change, and resulting guest release. The water-responsive nanocapsule is expected to be useful in a variety of fields.
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Authors: Sirirat Wacharawichanant, Nisarat Wimonsupakit, Sasithorn Kuhaudomlap
Abstract: The objective of this study is to fabricate the polyoxymethylene (POM)/microcrystalline cellulose (MCC) and poly(lactic acid) (PLA)/MCC composites, and to compare the effect of MCC on the morphology and mechanical properties of POM and PLA. The polymer composites were prepared by melt mixing in an internal mixer and molded by compression molding. The MCC concentrations were 1, 3, 5, 7, 10, 15 and 10% by weight. From scanning electron microscopy study observes the fracture surface of POM and PLA composites is much rough and the roughness increases with increasing MCC content. This observation indicates MCC induces the ductile fracture characteristic of POM and PLA. The addition of MCC can improve the impact strength of PLA composite and improve Young’s modulus of both POM and PLA composites. While the tensile strength and strain at break decrease after adding MCC. In summary, MCC can enhance the morphology and mechanical properties of PLA composites is better than POM composites.
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Authors: Agus Haryono, Muhammad Ghozali, Sri Budi Harmami, Yenny Meliana
Abstract: Polystyrene sulfonate (PSS) were prepared by sulfonation method of polystyrene using sulfuric acid. Abundant amount of polystyrene waste can be reused as a coagulant, membrane for polymer fuel cell and anionic-cationic polymer interactions. The characterization of PSS was carried out by using UV-Vis, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectra, molecular weight and analysis of sulfonation degree. The degree of sulfonation was obtained at 94,18%. Ionic interaction between anionic polymer PSS and cetyltrimethylammonium bromide (CTAB) as cationic compound in aqueous solution were analyzed by using dynamic light scattering (DLS), conductometry and fluorimetry. Behavior of conductivity have been calculated the critical micelle concentration (cmc). The FTIR and 1H-NMR spectra showed the ionic interaction between PSS and CTAB. This ionic interaction can be controlled by changing the polymer concentration.
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Authors: Le Chen, Zhao Zhan Gu, Ming Xue Zhang
Abstract: Coatings with flake carbonyl-iron powder as absorber and polyurethane resin as matrix were prepared. The complex permittivity, complex permeability and microwave-absorbing properties were investigated in the frequency range of 2–18 GHz. Both the complex permittivity and permeability of the flaky carbonyl-iron were increased compared to the spherical powders. The minimum reflection loss decreased and the matching frequency shifted to the lower frequency region with increase in the coating thickness. The band width can reach nearly 16GHz as the RL was below than-4 dB with thickness only 1.4 mm. The minimum reflection loss value of-14.5 dB was obtained at 3.56 GHz for the 1.6mm coatings with 89 wt% carbonyl-iron powders. These results showed that the coatings were favorable for the broadband low-frequency microwave absorption with a small thickness.
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Authors: Naomi Jane P. Jacosalem, Leo Cristobal C. Ambolode II
Abstract: Recent studies identified some factors that contribute to the enhancement of Tc in monolayer FeSe/STO superconductor. It has been claimed that electron doping and electron-phonon coupling play a crucial role in high-Tc superconductivity. However, electron doping and electron-phonon mechanism alone cannot fully explain the high-Tc of monolayer FeSe/STO. In this study, we introduce another factor, the Hubbard U correction, and investigate its effect. The electronic structure calculations on single-layer FeSe grown on STO using density functional theory with Hubbard U (DFT+U) is presented. It is found that the Hubbard U suppresses the hole-like band at the Brillouin zone center leading to an electronic structure that resembles the experimental ARPES data. This suggests that electron correlation in monolayer FeSe/STO system plays a crucial role in the origin of high-Tc superconductivity.
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Authors: Harun Özkişi, Seyfettin Dalgıç
Abstract: Recently, it has become indispensable to use semiconducting nanostructures in the production and development of electronic devices. In this study, the bulk and nanowire heterostructures of the BP / GaN system have been investigated for the structures pure and Te atom doped. In calculations, the plane wave self-consistent field program based on density functional theory was used. The average potentials of the aforementioned systems have been calculated and the interface effect has investigated.
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Authors: Cyron L. Custodio, John Lemuel G. Untalasco, Menandro C. Marquez
Abstract: Metal oxide semiconductors such as cobaltous oxide (Co3O4) and cuprous oxide (Cu2O) have caught the attention of many researchers due to their wide variety of applications. The attachment of Cu2O to Co3O4 was assisted by polyethylene glycol and the nanostructuring by ultrasonic sound. X-ray Diffraction (XRD) analysis of the fabricated composite reported characteristic peaks for crystalline Co3O4 and Cu2O. Results from Energy Dispersive X-ray (EDX) Spectroscopy showed the presence of cobalt, copper, and oxygen atoms which supports the result obtained in XRD. Cauliflower to nearly spherical shaped Cu2O - Co3O4 nanostructures were formed as observed in the Scanning Electron Micrographs (SEM) with a mean diameter of 0.5-1.0 μm. the shape of the composite and its surface morphology was altered with the use of different precursor materials for the synthesis of the Co3O4 seed. A blue shift in the UV-vis was observed upon the use of nitrate based precursor indicating the presence of smaller and finer particles in the composite. Overall results prove that Cu2O and Co3O4 can be synthesized using a facile solution approach with the aid of PEG and ultrasonic sound its application in the field of photocatalysis is probable.
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