Publications (9) View all
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Article: Novel Melt-Processable Nanocomposites Based on Isotactic Polypropylene and Carbon Nitride: Morphology, Crystallization, and Dynamic Mechanical Properties
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ABSTRACT: Light element-based materials like spherical carbon nitride (C3N4) particles were melt-mixed at different concentrations with isotactic polypropylene to produce new nanocomposites. The iPP/C3N4 nanocomposites were characterized with differential scanning calorimetry (DSC), time-resolved synchrotron X-ray scattering experiments, and dynamic mechanical analysis (DMA). On the basis of the DSC experimental and theoretical analyses, the study of the dynamic crystallization kinetics provides a picture describing the physicochemical transformation of iPP molecules from the non-ordered state to the ordered state. The addition of C3N4 induces an increase of the crystallization rate and crystallinity of the polymer matrix, without variation of the crystalline structure of iPP. In the same way, the results of the nucleation activity confirmed the nucleating effect of C3N4 on the iPP crystallization. However, the addition of C3N4 causes an alteration of the effective energy barrier of the crystal growth process of iPP. The DMA studies revealed the reinforcing effect of the C3N4 on the mechanical performance of iPP with an increase in the storage modulus of around 32%. Moreover, the heat deflection temperature of iPP increased considerably, whereas the damping property was found to decrease because the C3N4 acted as barriers to the free movement of the iPP macromolecular chain.Soft Materials 10/2010; 8(4):407-425. · 1.15 Impact Factor -
Article: Anodic aluminium oxide membranes used for the growth of carbon nanotubes.
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ABSTRACT: The suitability of anodic aluminum oxide (AAO) membranes as template supported on Si substrates for obtaining organized iron catalyst for carbon nanotube (CNT) growth has been investigated. The iron catalyst was confined in the holes of the AAO membrane. CVD synthesis with ethylene as carbon source led to a variety of carbon structures (nanotubes, helices, bamboo-like, etc). In absence of AAO membrane the catalyst was homogeneously distributed on the Si surface producing a high density of micron-length CNTs.Journal of Nanoscience and Nanotechnology 11/2009; 9(11):6396-400. · 1.56 Impact Factor -
Article: Azafullerene-like nanosized clusters.
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ABSTRACT: Carbon nitride materials have extraordinary potential in various applications, including catalysts, filled-particles, and superhard materials. Carbon nitride nanoclusters have been prepared under mild solvothermal conditions by a reaction between 1,3,5-trichlotriazine and sodium azide in toluene. The bulk material formed has a C(3)N(4) composition and consists of spheres with diameters ranging from approximately 1 nm to 4 mum. Nanometer-sized clusters of C(3)N(4) stoichiometry have been isolated on surfaces by sublimation or simple physicochemical methods. The clusters have then been characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The laser desorption ionization mass spectra show peaks assignable to the C(12)N(16), C(21)N(28), and C(33)N(44) molecules which could correspond to cage structures with 4, 7, and 11 units of the C(3)N(4) subunit, respectively. The structure and stability of these new nitrogen-rich carbon nitride nanocages has been investigated using density functional theory calculations.ACS Nano 10/2009; 3(11):3352-7. · 10.77 Impact Factor -
Article: Dependence of the single walled carbon nanotube length with growth temperature and catalyst density by chemical vapor deposition.
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ABSTRACT: We report the growth of isolated single walled carbon nanotubes (SWCNTs) on a silicon surface by chemical vapor deposition, in the temperature range from 800 to 950 degrees C using two different iron catalyst precursors, Fe(NO3)3 x 9H2O and Fe(CO)5. The results show that while for the first catalyst precursor temperature is the key factor in determining nanotube length, for the second it is the density of catalyst precursor on the surface. Solutions of Fe(CO)5 adsorbed on silicon oxide result in a suitable catalyst precursor to obtain SWCNTs of controllable diameter and with clean surfaces.Journal of Nanoscience and Nanotechnology 06/2009; 9(5):2830-5. · 1.56 Impact Factor -
Article: Strain energy and lateral friction force distributions of carbon nanotubes manipulated into shapes by atomic force microscopy
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ABSTRACT: The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes on a clean SiO2 substrate. Using only high resolution atomic force microscopy images of curved single walled nanotubes, we estimate flexural strain energy distributions on the order of attojoules per nanometer and the static frictional forces between a SWCNT and SiO2 surface to be a minimum of 230 pN nm(-1).Birck and NCN Publications.
