Search

Rubber/nanocellulose composite sheets improve tensile properties compared with neat rubber sheets, when nanocellulose materials are suitably compounded with rubber matrices. First, two oven‐dried nanocellulose materials containing different additive components were prepared from nanocellulose/water dispersions, and the oven‐dried nanocellulose‐containing materials were compounded with rubber sheets under high shear forces by using a two‐roll mill. The tensile moduli and strength of the rubber/nanocellulose composite sheets were clearly better than those of the rubber sheet prepared without nanocellulose, while the elongations at break were similar. Thin films were cut from the rubber/nanocellulose composite sheets, and their real‐time tensile deformation processes were observed by transmission electron microscopy (TEM) to understand the time‐dependent patterns of crack propagation, void formations, and fusion between cracks and voids in the composites during tensile deformation. TEM observations showed that the composite sheets consisted of individual rubber/nanocellulose clusters. Voids initially formed inside the rubber/nanocellulose clusters, propagated to form cracks, fused with other voids or secondary cracks. There were slight differences between the crack‐propagation patterns of the two rubber composites, probably because of differences in the morphologies, sizes, distributions, and structures of the rubber/nanocellulose clusters, and surface chemical structures of individual nanocellulose elements between the composites. [ABSTRACT FROM AUTHOR]

Synthesizing 3D carbon nanotube (CNT) networks with multifunctional characteristics has stimulated the interest from the scientific community since the 1990s. Here, the fabrication of a novel composite material consisting of 3D covalently interconnected multiwalled CNT with silicon carbide (SiC) nano and microparticles is reported. The material is synthesized by a two-step process involving the coating of CNT with silicon oxide (SiO x) via chemical routes, followed by spark plasma sintering (SPS). SPS enables carbothermal reduction of SiOx and subsequent densification of the material into 3D composite blocks. Covalent interconnections of CNT are facilitated by a carbon diffusion process resulting in SiC formation as SiOx coated CNT are subjected to high temperatures. The presence of SiC in the sintered composite has been confirmed by Raman spectroscopy, as well as through energy filtered transmission electron microscopy maps. Interestingly, the 3D CNT composite exhibits high thermal conductivity (16.72 W m−1 K−1); and also a semiconducting behavior with an electron hopping mechanism associated to a 3D variable range hopping model. These findings demonstrate that it is indeed possible to fabricate SiC-CNT composites with enhanced physical properties that can be used as multifunctional materials. [ABSTRACT FROM AUTHOR]

Recently, the lattice image of well ordered carbons can be observed pretty easily by high-resolution transmission electron microscopy (HRTEM). In this study, the cross section of the new type carbon nanofiber, of which the special structure was unknown, was observed by HRTEM and the detailed structure was analyzed by image processing. Defects were observed in the ordered structure of this material, that is, the (00·1) lattice planes show large fluctuation in alignment of them and the (10·0) lattice planes make several angles with the (00·1) lattice planes. The average repeat distance d 002 was estimated by HRTEM image and image analysis. [ABSTRACT FROM AUTHOR]

High-resolution transmission electron microscopy study of ball-milled lampshade carbon nanofibers is reported in the present paper. Milled fibers became shorter in length, preserving the lampshade structure with highly ordered graphene layers. We have also shown the simulated model for the shortening process of the fiber. [ABSTRACT FROM AUTHOR]

We report the controlled growth of one-dimensional clusters of molybdenum atoms inside the inner cores of double-walled carbon nanotubes. A combined characterization including high resolution transmission electron microscopy, nitrogen adsorption measurement at 77 K, x-ray photoelectron spectroscopy, Raman spectroscopy, and thermogravimetric analysis reveals that the growth of one-dimensional Mo clusters can be controlled by varying the reaction conditions. The products have specific surface areas of 360–480 m2 g-1, and their characteristic properties are attributed to the presence of Mo cluster, which affect the electronic structure and can be exploited for the development of nanotube electronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The instability of single-walled carbon nanotubes (SWCNTs) under compressive loading has been observed experimentally by TEM and may limit their performance and structural integrity as atomic force microscopy (AFM) tips. Double-walled carbon nanotubes (DWCNTs) with inner and outer nanotubes of different lengths are proposed as AFM probes, and a theoretical approach based on a nanobeam model is developed for investigating the critical buckling stress of the DWCNTs under an axial compressive load. The influence of structural parameters on the buckling stress of DWCNT AFM probes are analyzed using this approach. The results show that the influence of the length mismatch between inner and outer nanotubes, as well as buckling modes on the buckling stress of DWCNTs was significant. [Copyright &y& Elsevier]

Abstract: The multi-walled carbon nanotubes (MWCNTs, mean diameter: 100–200nm) with nickel–phosphorous (Ni–P) coatings were obtained by an electroless deposition process. To prepare the MWCNTs covered with continual Ni–P layers, a pre-treatment procedure comprised of acid-cleaning, sensitization and activation has been developed. The resulting MWCNTs have a uniform distribution of the Ni–P layers coated on the MWCNTs with the fibrous appearance maintained. X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations revealed that the as-coated MWCNTs were comprised of the amorphous Ni–P layers and inner carbon nanotubes covered with the Ni–P layers. These amorphous Ni–P-coated MWCNTs were used as precursors for preparing MWCNTs with nanocrystalline Ni–P(crystalline Ni and Ni3P intermetallic compound) layers by the heat-treatment above 400°C, which were determined by differential scanning calorimeter (DSC) and XRD studies. The results of this work provide an effective electrochemical method for preparing powdery MWCNTs with Ni–P layer as new composite materials from the aqueous solution. [Copyright &y& Elsevier]

Abstract: Copper oxide nanoparticles (CuONPs) were successfully decorated on acid treated multi-wall carbon nanotubes (f-MWCNTs) using copper acetate precursor by a very simple “mix and heat” method, and was used as a heterogeneous nanocatalyst for the N-arylation of imidazole for the first time. The transmission electron microscopic (TEM) images of the prepared nanocatalyst (CuO/MWCNT) showed a good adhesion of CuONPs on anchoring sites of the MWCNTs. The factual loading of Cu in CuO/MWCNT was 7.64 wt% as confirmed by inductively coupled plasma-mass spectrometry (ICP-MS). The chemical state of Cu on MWCNTs was +2 as revealed by wide angle X-ray diffraction (WAXD), X-ray photoelectron spectroscopic (XPS) and temperature programmed reduction (TPR) techniques. Initially the reaction conditions were optimized and then the scope of the catalytic system was extended with different aryl halides. 0.98mol% (5mg) of the catalyst was sufficient for N-arylation of imidazole. A literature survey showed that this is the smallest amount of catalyst used for this reaction in research reported to date. The CuO/MWCNT is chemically as well as physically very stable, heterogeneous in nature and reusable. After the catalytic reaction, MWCNTs were successfully separated from the used CuO/MWCNT and characterized by Raman, TEM and WAXD. [Copyright &y& Elsevier]

An outstanding compression function for materials preparation exhibited by nanospaces of single-walled carbon nanohorns (SWCNHs) was studied using the B1-to-B2 solid phase transition of KI crystals at 1.9 GPa. High-resolution transmission electron microscopy and synchrotron X-ray diffraction examinations provided evidence that KI nanocrystals doped in the nanotube spaces of SWCNHs at pressures below 0.1 MPa had the super-high-pressure B2 phase structure, which is induced at pressures above 1.9 GPa in bulk KI crystals. This finding of the supercompression function of the carbon nanotubular spaces can lead to the development of a new compression-free route to precious materials whose syntheses require the application of high pressure. [ABSTRACT FROM AUTHOR]

Abstract: Recent findings of extremely small diameter carbon nanotube and nanowire in the core of a multi-walled carbon nanotube (MWCNT) have attracted interests from broad range of researchers. Direct observation of carbon nanotube is usually done using a transmission electron microscope (TEM). When nanotubes become smaller, it becomes harder to correctly understand the TEM images, not only because of the weak scattering, but also due to the artifact that starts to appear because of the interference effect and the inappropriate defocus condition. In this study, we have shown that the artifact such as ghost fringes due to inappropriate defocus conditions of the TEM appear in the core of an MWCNT, and can be misinterpreted as either carbon nanowire or small carbon nanotube. It is also shown that, in the TEM image, it is hard to distinguish a single-walled nanotube bundle from a double-walled carbon nanotube bundle. Finally, we propose that the cross-sectional observation is necessary for the correct characterization of single- and double-walled carbon nanotube bundles. [Copyright &y& Elsevier]

We report the synthesis of high purity double-wall carbon nanotubes encapsulating GdCl3 nanowires (GdCl3@DWCNTs). The obtained GdCl3@DWCNTs were characterized by transmission electron microscopy (TEM), Raman spectroscopy, UV–Vis-NIR spectroscopy, and fluorescence spectroscopy. TEM measurements show that GdCl3 impurities were absent on the exterior of the tubes and bundles. Furthermore, significant changes of the optical properties of the inner tubes were not triggered by being filled with GdCl3 nanowires, which suggests that significant charge transfer does not occur between the encapsulated GdCl3 and the inner tubes. Our results indicate that GdCl3@DWCNTs could be useful for various applications using the expected magnetic properties of GdCl3 and almost unchanged optical properties of DWCNTs. [TANSO 2013 (No. 260) 279–83.] [ABSTRACT FROM AUTHOR]

Techniques for the structural and morphological characterization of carbon materials using microscopy and image processing are reviewed. These techniques are high resolution transmission electron microscopy (HRTEM), three dimensional transmission electron microscopy (3D-TEM) and two dimensional fast Fourier transform (2D-FFT). They are applied to the structural analysis of carbon nanotubes loaded with metal particles, activated carbon, and thin graphite. A HRTEM with C s corrector can achieve a high resolution of less than 0.1nm even if the acceleration voltage is 80kV. The more precise three dimensional structure of the carbon nanotubes and activated carbon can be revealed by using 3D-TEM combined with HRTEM. The 2D-FFT of lattice images of HRTEM can analyze the structure of nano structured carbons, like selected area electron diffraction (SAED) which is difficult to apply to the microscopic area. 2D-FFT can be an alternative technique to SAED for nano-size analysis. HRTEM, 3D-TEM, and image processing thus can provide a powerful tool for the analysis of the structure and morphology of nanostructured carbons. [TANSO 2012 (No. 255), 292–304.] [Copyright &y& Elsevier]