Search results for "Electron microscope"
showing 10 items of 784 documents
Young’s modulus and indirect morphological analysis of Bi2Se3nanoribbons by resonance measurements
2017
An electrostatically induced resonance behaviour of individual topological insulator Bi2Se3 nanoribbons grown by a catalyst free vapour-solid synthesis was studied in situ by scanning electron microscopy. It was demonstrated that the relation between the resonant frequencies of vibrations in orthogonal planes can be applied to distinguish the nanoribbons with rectangular cross-sections from the nanoribbons having step-like morphology (terraces). The average Young's modulus of the Bi2Se3 nanoribbons with rectangular cross-sections was found to be 44 ± 4 GPa.
Morphology and transport parameters of cold-rolled low-density polyethylene
1986
Abstract Sheets of low-density polyethylene were rolled at room temperature. Samples with two different degrees of rolling were obtained. The structural changes induced by the rolling treatments were investigated using scanning electron microscopy and by analyzing the transport properties. Results suggest that in the analyzed range of deformation, the rolling induces a domain structure as a consequence of a nonhomogeneous distribution of the deformation. At lower local deformation the initial morphology is still present, while at higher deformation clumps of folded chains oriented along the rolling directions are observable. The transport properties indicate that the rolling treatment reduc…
Physical behavior and morphology of biaxially rolled low-density polyethyleneX
1989
Abstract Biaxial rolling was carried out on low-density polyethylene, and the rolled samples were studied using various techniques. Scanning electron microscopy and analysis of transport properties were used to obtain structural information, which was correlated to thermomechanical and dynamic-mechanical behavior. Results indicate that the initial morphology is destroyed by rolling and that clumps of molecules, like fibrils, are generated parallel to the rolling plane. The molecular orientation in the plane is mainly radial, with some reinforcement, particularly at high rolling degree, along axes diagonal with respect to the rolling directions. The rolling drastically reduces the molecular …
In vitro degradation and bioactivity of composite poly-l-lactic (PLLA)/bioactive glass (BG) scaffolds: comparison of 45S5 and 1393BG compositions
2017
The objective of this study was to compare the effect of two bioglass (BG) compositions 45S5 and 1393 in poly-l-lactic composite scaffolds in terms of morphology, mechanical properties, biodegradation, water uptake and bioactivity. The scaffolds were produced via thermally induced phase separation starting from a ternary polymer solution (polymer/solvent/non-solvent). Furthermore, different BG to polymer ratios have been selected (1, 2.5, 5% wt/wt) to evaluate the effect of the amount of filler on the composite structure. Results show that the addition of 1393BG does not affect the scaffold morphology, whereas the 45S5BG at the highest amount tends to appreciably modify the scaffold archite…
'Cold' crystallization in nanostructurized 80GeSe2-20Ga2Se3 glass
2015
International audience; 'Cold' crystallization in 80GeSe 2-20Ga 2 Se 3 chalcogenide glass nanostructurized due to thermal annealing at 380°C for 10, 25, 50, 80, and 100 h are probed with X-ray diffraction, atomic force, and scanning electron microscopy, as well as positron annihilation spectroscopy performed in positron annihilation lifetime and Doppler broadening of annihilation line modes. It is shown that changes in defect-related component in the fit of experimental positron lifetime spectra for nanocrystallized glasses testify in favor of structural fragmentation of larger free-volume entities into smaller ones. Nanocrystallites of Ga 2 Se 3 and/or GeGa 4 Se 8 phases and prevalent GeSe…
Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites
2014
Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H2SO4/H3PO4 and KMnO4 based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectrosco…
Novel Au NPs/Preyssler acid/TiO 2 nanocomposite for the photocatalytic removal of azo dye
2014
Abstract In this study, we introduced a novel nanocomposite consisting of Au nanoparticles decorated TiO 2 and Preyssler acid as a multifunctional photocatalyst linker molecule, in which gold ions reduced locally on the TiO 2 surface. The obtained nanocomposite has been characterized using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), Electron Dispersive X-ray (EDX) Spectroscopy, Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM). Also, their photocatalytic activity has been studied for the degradation of model organic azo dye Malachite Green under UV light irradiation.
Development of self-assembled bacterial cellulose–starch nanocomposites
2009
Abstract A bioinspired bottom-up process was developed to produce self-assembled nanocomposites of cellulose synthesized by Acetobacter bacteria and native starch. This process takes advantage of the way some bacteria extrude cellulose nanofibres and of the transport process that occurs during the gelatinization of starch. Potato and corn starch were added into the culture medium and partially gelatinized in order to allow the cellulose nanofibrils to grow in the presence of a starch phase. The bacterial cellulose (BC)–starch gels were hot pressed into sheets that had a BC volume fraction higher than 90%. During this step starch was forced to further penetrate the BC network. The self-assem…
Real-time measurements of sliding friction and elastic properties of ZnO nanowires inside a scanning electron microscope
2011
Abstract A real-time nanomanipulation technique inside a scanning electron microscope (SEM) has been used to investigate the elastic and frictional (tribological) properties of zinc oxide nanowires (NWs). A NW was translated over a surface of an oxidised silicon wafer using a nanomanipulator with a glued atomic-force microscopic tip. The shape of the NW elastically deformed during the translation was used to determine the distributed kinetic friction force. The same NW was then positioned half-suspended on edges of trenches cut by a focused ion beam through a silicon wafer. In order to measure Young’s modulus, the NW was bent by pushing it at the free end with the tip, and the interaction f…
Real-time manipulation of gold nanoparticles inside a scanning electron microscope
2011
Abstract The forces needed to overcome static friction and move 150 nm diameter Au nanoparticles on an oxidized Si substrate were measured in Normal and Shear oscillation modes inside a scanning electron microscope (SEM) in real time. The experimental setup consisted of a quartz tuning fork (QTF) mounted onto a high-precision 3D nanomanipulator used with a glued silicon or tungsten tip as a force sensor. Static friction was found to range from tens of nN to several hundred nN. Large variations in static friction values were related to differences in particle shape. Kinetic friction tended to be close to the detection limit and in most cases did not exceed several nN. The influence of therma…