Results 1 - 10 of 1914
Results 1 - 10 of 1914. Search took: 0.027 seconds
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[en] High-performance microwave absorbers with excellent absorption ability and superhydrophobic property are extremely significant for the application of stealthy techniques, especially in high-humidity environment. In this research, high-performance Co-C nanofibers (NFs) were prepared via electrospinning mathod by using of poly (vinyl alcohol) (PVA) and Cobalt acetate tetrahydrate (CoAc) solution as precursor with subsequent PVA pyrolyzation and carbonization process. The electromagnetic (EM) parameters and microwave absorption performance of the prepared NFs were investigated with the microwave frequency ranging from 2.0 GHz to 18.0 GHz. Analysis and comparison were performed on the impedance matching and loss mechanisms of each sample. The experimental results indicated that the sample calcinated at 950 °C achieved an optimal reflection loss (RL) of − 33.1 dB and an effective frequency bandwidth of 4.1 GHz under a thickness of 1.5 mm; and that the Co-C NFs membrane with the optimal absorption performance exhibited superhydrophobic property with a contact angle (CA) of 152°, suggesting their promising application to water-resistant stealthy materials.
[en] The spatial control of the nano-emitters in novel light harvesting platforms offers great potential for the manipulation of the excitonic interaction amongst the donor–acceptor pairs of energy transferring agents. In this work, we report colloidal quantum dot loaded electrospun nanofibers as a light harvesting platform to study the excitonic interaction among them. The donor emission lifetime modified from 12.46 ns to 7.45 ns with the change in the ratio of green and red quantum dots in the nanofiber, as a result of confining acceptor quantum dots in close proximity. The spectrally narrow emitter luminescent nanofiber platforms have further been investigated for their potential of white light generation. The hybrid platform of blue LED integrated electrospun nanofibers has been shown to demonstrate a correlated color temperature of 3632.5 K, luminous efficacy of optical radiation value of 307.7 lm/W opt along with color rendering index value of 60. (paper)
[en] Poly(lactic acid) (PLA) nanocomposite films reinforced with acetylated bacterial cellulose nanoribbons were prepared by solvent casting. Acetylation of bacterial cellulose (BC) was performed by an innovative and sustainable direct solvent-free route catalyzed by citric acid. The effect of derivatization and its extent on the morphological, optical, thermal and mechanical properties of the nanocomposites was analyzed. Data collected from the above studies showed that acetylation of BC nanoribbons clearly improved the nanofibers dispersion in the PLA matrix with respect to unmodified BC, which in turn resulted in increased transparency and mechanical properties of the nanocomposites produced.
[en] In this study, gelatin–polyethylenimine blend nanofibers (GEL/PEI) were fabricated via electrospinning with different ratios (9:1, 6:1, 3:1) to integrate the properties of both the polymers for evaluating its biomedical application. From scanning electron microscopy, the average diameter of blend nanofibers (265 ± 0.074 nm to 340 ± 0.088 nm) was observed to be less than GEL nanofibers (403 ± 0.08 nm). The incorporation of PEI with gelatin resulted in improved thermal stability of nanofibers whereas the Young’s modulus was observed to be higher at 9:1 ratio when compared with other ratios. The in vitro studies showed that the GEL/PEI nanofibers with 9:1 ratio promoted better cell adhesion and viability. GEL/PEI nanofibers with 9:1 and 6:1 showed hemolysis within the permissible limits. From the results, it could be interpreted that GEL/PEI nanofibers with 9:1 ratio proved to be a better scaffold thereby making them a potential candidate for tissue engineering applications.
[en] The helical micro/nanofiber arrays of polyvinylpyrrolidone (PVP) were successfully prepared by Near-field electrospinning(NFES) with different concentrations of PVP and different voltages by a gradient of per 0.5 kV from 1 kV to 2.2 kV. It is found that the morphology of the arrayed fibers evolved with regularity with the increase of the working voltage, and the uniformity of the fiber arrays also increased. The formation mechanism of the arrayed helical micro/nanofibers was analyzed. This may be a cost-effective method for the large-scale production of morphologically controllable spiral fibers, which opens up an effective way for the precise and controlled deposition of electrospun helical fibers and the integration of single or array spiral fibers with functional devices. (paper)
[en] Optical forces exerted upon the endface of optical nanofiber have been carefully investigated numerically. Detailed spatial optical force distributions along the fiber axis are obtained. Dependence of optical force on fiber diameters, input modal polarizations, oblique-cut endfaces are carefully taken into considerations. It is clear now that oblique-cut fiber endface should be responsible for sideways deflection of nanofiber. (paper)
[en] Highlights: • Ba-doped LaFeO3 nanofibers (NFs) were prepared by a facile electrospinning process. • Ba-doping promotes the sensing response of LaFeO3 NFs toward ethanol gas. • Ba-doped LaFeO3 NFs have a relatively low optimum operating temperature. • La0.75Ba0.25FeO3 NFs show the highest sensitivity and rapid response-recovery. • The good performance is attributed to the unique structure and morphology feature of NFs.
[en] Electrospinning is one of the most used processes for the production of nanofibers, due to its simplicity and versatility. This paper presents the current state of the melt electrospinning, which is less used than the solution electrospinning but which is the only way of electrospinning polymers with very limited solubility and high electrical resistivity such as polyolefins. The advantages of melt electrospinning, as well as the constraints of this method, are reviewed, and the factors that influence the process are described. The paper are presented the main applicability domains of nanofibers obtained in this way and the prospects of future development. (paper)
[en] A new type of hydrophobic polyacrylonitrile (PAN) nanofiber is fabricated by solution blowing of a blend solution of fluorine-containing polyacrylate (FPA) and PAN. The nanofibers’ surface composition, hydrophobicity, and protection ability were evaluated to clarify the effects of FPA addition. Results revealed that FPA addition increased the nanofiber diameter, as well as enhanced the hydrophobicity and transport properties of the nanofiber mats. The mats had average water contact angles of 123.44°, 132.11°, and 137.11° for FPA contents of 0.66 wt%, 1.98 wt%, and 3.30 wt%, respectively. All these results suggested the potential of the solution blowing nanofiber mats as protection materials.
[en] In this study, a flexible highly sensitive strain sensor was fabricated using thermoplastic polyurethane (TPU) and carbonized woven fabric based on polyacrylonitrile nanofiber yarn (PNY). The carbonized PNY fabric was prepared according to the following steps: filaments fabricated by electro spinning were twisted into a yarn; the yarn was treated by a sizing agent and weaved as a weft yarn; subsequently, the woven fabric was washed, pressed, and dried; finally, the carbonized PNY woven fabric was obtained through stabilization and carbonization. The effects of the thickness of the TPU film and the structure of the fabric on the sensing properties are discussed. The flexible strain sensor exhibits excellent sensitivity in the high-sensing strain range (average gauge factor = 77.3 within 12% strain) and high durability and stability (more than 1000 stretching cycles at 5% strain). Moreover, the strain sensor exhibits an excellent linear relationship between the strain and relative resistance change and accurately detects a full range of human activities (both vigorous and subtle). Such flexible highly sensitive strain sensors can be easily incorporated onto the surfaces of textiles and within electronics for use in various applications, toward applications such as smart textiles and health monitoring.