Carbon-based nanostructures continue to attract a disproportionate share of research effort because of their wide range of properties. This research includes synthesis techniques and controlling the structure and morphology of nanomaterials, since for many applications tedious manipulations are often required. One of the problems faced in such a characterization is contamination. Carbon nanotubes (CNTs) have been synthesized by hot filament plasma enhanced catalytic chemical vapour deposition (HF PE CCVD) and investigated by x-ray absorption near-edge spectroscopy (XANES). The spectra showed that samples with a large surface curvature are less sensitive to thermal treatment. Among the contaminants, we find potassium, which may have come from the beam line.

We report a quantitative x-ray absorption spectroscopy (XAS) study of the orientation of carbon nanotubes (CNTs) grown on plain SiO2(thickness 8 nm)/Si(100) substrates by a catalytically enhanced dc hot filament chemical vapour deposition (CVD) process. The alignment and orientation of CNT films are generally provided in the literature by scanning electron microscope (SEM) and transmission electron microscope (TEM) images qualitatively. A very few other techniques have been used to more deeply study the alignment of CNTs grown by the CVD technique, such as x-ray diffraction (XRD) or grazing-incidence small-angle x-ray scattering (GISAXS). XAS recorded on the C K-edge provides information on the local environment around carbon atoms and helps us study the orientation of CNTs. We find spectral features very similar to those of HOPG, in agreement with the literature. Meanwhile, we do not observe any extinction of the π* band at grazing incidence. CNTs have an averaged direction perpendicular to the surface of the substrate.

X-Ray Absorption Spectroscopy (XAS) on the carbon K edge of carbon nanostructures (nanotubes, nanofibers, nanowalls) is reported here. They are grown on plain SiO2 (8 nm thick)/Si(100) substrates by a Plasma and Hot Filaments-enhanced Catalytic Chemical Vapor Deposition (PE HF CCVD) process. The morphology and the nature of these carbon nanostructures are characterized by SEM, TEM and Raman spectroscopy. According to conditions of catalyst preparation and DC HF CCVD process, carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanowalls (CNWs), carbon nanoparticles (CNPs) with different orientation of the graphene plans or shells can be prepared. From the angular dependence of the incident light and geometrical morphology of the nanostructures, wide variations of the C K-edge intensity of the transitions to the empty * π and * σ states occur. A full lineshape analysis of the XAS spectra has been carried out using a home-made software, allowing estimating the relative proportion of * π and * σ transitions. A geometrical model of the angular dependence with the incidence angle of the light and the morphology of the carbon nanostructures is derived. With normalization to the HOPG (Highly Oriented Pyrolytic Graphite graphite) reference case, a degree of alignment can be extracted which is representative of the localized orientation of the graphitic carbon π bonds, accounting not only for the overall orientation, but also for local defects like impurities incorporation, structural defects ... This degree of alignment shows good agreement with SEM observations. Thus CNTs films display degrees J. M. Mane et al. 967 of alignment around 50%, depending on the occurrence of defects in the course of the growth, whereas no special alignment can be detected with CNFs and CNPs, and a weak one (about 20%) is detected on CNWs.

The influences of incorporating compatibilizers E-EA-MAH, E-MA-GMA, E-AM, SEBS KRATON G, or PP-g-MAH on the thermal properties of mixed (polypropylene/ethylene propylene rubber)/acrylonitrile butadiene styrene (PP/EPR)/ABS have been investigated. DSC investigations have revealed that the incorporation of 5% of ABS in the copolymer (PP/EPR) does not fundamentally affect the thermal properties of the basic copolymer; additionally, the addition of 1.5% of each of the compatibilizers in the basic mixture does not significantly alter the crystallization temperature values and the melting of the -P-sequences. There is a variation of melting enthalpy values of the -P-sequences of 18.23% using SEBS KRATON G and of 10.38% using E-AM-GMA. When the rate of each of the compatibilizers increases to 5%, overall crystallization enthalpies of -P-sequences are almost kept unchanged, except for the case of using the compatibilizer E-AM-GMA with a variation of 8.42%. There is a minor variation of the melting enthalpy of -P-sequences with higher levels of compatibilizer. The incorporation of 5% ABS copolymer in the PP/EPR does not significantly alter the thermal properties of the basic structure of (PP/EPR)/ABS.

We report on a quantitative Grazing Incidence Small Angle X-ray Scattering (GISAXS) study of the angular dependence of oriented carbon nanotubes (CNTs) grown by a catalytically activated, plasma direct current or plasma enhanced and hot filaments-assisted catalytic chemical vapour deposition (dc HF CCVD or PE HF CCVD) process. To synthesize these CNTs, some transition metal (TM) particles were used as a catalyst and dispersed on plain SiO2 (thickness 5 nm)/Si(100) substrates prior to the growth of CNTs. Some morphological (diameter, height) and disorder parameters have been determined using the GISAXS technique in the framework of Effective Layer Born Approximation (ELBA) and Distorted-Wave Born Approximation (DWBA) on noncorrelated multilayer systems. The GISAXS patterns, although dominated by envelope features of disordered islands, provide important complementary quantitative information about CNT films. The results are compared to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. Furthermore, the GISAXS patterns could only be acceptably reproduced by considering an inter-mixing C–Co contribution and the metallic cobalt let on top of the CNT. While monitoring the incidence angle, we found that the disorder parameter decreases with increasing incidence angle, showing that the in-plane system order increases from the surface to the inner layers.