Synthesis, Characterization and Application of Carbon Nanotubes and Carbon Nanofibers PDF Download

Author: Muataz Ali Atieh Hussein
Publisher:
ISBN:
Category : Carbon
Languages : en
Pages : 420

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Book Description
Well aligned wall carbon nanotubes (MWCNTs), carbon nanofibers (CNFs) and other type of carbon nanostructures materials have been synthesized by a fabricated floating catalyst chemical vapor deposition (FC-CVD) method. This involved the pyrolysis of benzen-ferrocene vapor mixture. The CVD parameters (Hydrogen flow rate, reaction time and reaction temperature) were studied to selectively synthesize nanotubes and nanofibers with required dimensions. Carbon nanotubes films with a diameter of 2-50 nm and nanofiber with a diameter range from 100-300 nm were synthesized in a benzene/hydrogen atmosphere. Furthermore vapor grown carbon fibers have been synthesized with different diameters and lengths. Iron clusters that were produced from the thermal decomposition of ferrocene films were used as caralyst for the synthesis of the carbon structures. The effects of different hydrogen flow rates (50-500 ml/min) on the morphology, quality and quantity of the product were investigated. Maximum yield and purity was obtained at 300 ml/min. The effect of the reaction time on the purity and yield of carbon nanotubes was studied from 1 minutes to 60 minutes. There was no effect of the reaction time on the average diameter while maximum yield of carbon nanotubes was achieved at 45 minutes. The last variables was the reaction temperature, which was varied from 500 oC to 1200 oC. By controlling the growth temperature, carbon nanotubes (CNTs), carbon nanofibers (CNFs) and vapor grown carbon fiber with different structures were produced. Increasing the temperature has a remarkable effect on the size and shape of the catalyst and this in turn affected the diameter distribution and structure of the carbon materials. The carbon nanotubes were produced from 600 oC to 850 oC with maximum yield at 850 oC, while for the production of carbon nanofibers the reaction temperature was from 900 oC to 1000 oC with a maximum yield at 1000 oC. Vapor grown carbon fibers were produced at 1050 oC to 1200 oC with maximum yield at 1050 oC. The synthesized nanotubes/nanofibers were invertigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal degradation kinetics of CNTs was investigated by dynamic thermogravity, in an air atmosphere, over the temperature range 25-800 oC and at constant nominal heating rate 10 oC/min. The correcponding activation energies, frequency factors and reaction orders were determined. Homogenous distribution of MWCNTs/CNFs in natural rubber (NR) was achieved by ultraconic assisted solution-evaporating method. Addition of 1-10 wt% of CNFs and CNTs to natural rubber as nanocomposite increased the rubber mechanical properties significantly. The properties of the composites such as tensile strength, tensile modulus, and elongation at break were studied. In addition to mechanical testing, the dispersion state of the MWNTs into NR was studied by TEM in order to understand the morphology of the resulting system. The result indicate that, by increasing the amount of CNTs and CNFs into natural rubber the ductility decreased and the material become stronger and tougher but at the same time more brittle. The results showed that by adding 1 wt% of CNTs and CNFs to NR the stress level increased sharply to 0.56413 to 0.54 Mpa respectively compared to NR which was 0.2839 MPa. At 10 wt% the stress level of CNTs with NR were increased sharply 9 times and reached to 2.55 MPa while for CNFs it increased 4.66 times and reached to 1.33 MPa.