Thesis on carbon nanofibers

This correlation, along with the reliable method of fiber conductivity measurement by IDE, presents a way to resolve some of the inconsistencies in the literature about reporting electrical conductivity values of electrospun fibers and fiber mats.

Search articles by author. Application of the required higher reduction temperature resulted in complete reduction for that sample, accompanied by sintering of platinum to large agglomerates.

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This transition phase was confirmed by differential scanning calorimetry studies. We have first developed a reliable method to characterize fiber electrical conductivity using interdigitated electrodes IDE and high-impedance analyzers with contact-resistance corrections, and applied to electrospun conductive polymer nanofibers.

This was most likely due to the tendency of CNTs to shorten when sonicated. Catalytic activity of titania NPs are estimated to be an order of magnitude lower than iron NPs, and a lift-off mechanism for titania NP catalysts is described, indicating that several layers of graphene will cause lift-off, consistent with HRTEM observations of layer graphite within the CNFs.

A detailed study of the electrical and thermal properties of electrospun fibers was presented in our study. As shown in Figure 4increasing the sample temperature drastically reduced the electrical resistance.

The highest young's modulus was also obtained in the 1. Biomedical and Chemical Engineering — Theses. For reproduction of material from PCCP: Considerable amount of recent work has been reported trying to make electrospun polymeric nanofibers with intrinsically conductive polymers or composites.

A good dispersion technique is essential for allowing the formation of an interconnecting filler network of CNTs at a lower concentration without changing the electrical resistivity.

The thickness of the sample decreases under the load, and the contact area between the fibers and electrode increases, which in turn reduces the overall electrical resistance.

Department of Materials Science and Engineering. Before heat-treatment, the platinum catalysts with larger metal particles turned out to be more selective. When the polymer is strained, it must overcome the energy barrier in order to allow the polymer chains to move around and rotate the chain bonds.

Since the mechanism of heating the polymer above room temperature is thermally induced, the resistance versus temperature behavior may be understood by the activation energy values of the nanocomposite fibers. Polymer Nanocomposites Polymer-carbon nanotube CNT composites have recently attracted a considerable amount of scientific interest because of their structural characteristics, such as high aspect ratio, surface area, and electrical, thermal, and mechanical properties, all of which are positive signs for the fabrication of ultralightweight and robust composites [ 14 ].

Lithium-ion battery anodes with a nanostructure of randomly dispersed carbon nanofibers CNFscarbon nanotubes CNTsand nanoparticles of tin-oxide or silicon were fabricated and tested in order to develop high capacity, easily manufactured anodes.

Those factors that influence the resistance are mainly porosity, charge carrier concentration, and polarizability of inclusions in the polymer matrix. Abstract of New approach to carbon dioxide utilization: For reproduction of material from NJC: This method was shown to be reliable and sensitive, as opposed to some of the other methods that have been reported in literature.

Results and Discussion 3. These included the addition of polyvinylidene fluoride PVDF or carbonized phenolic resins. The certified thesis is available in the Institute Archives and Special Collections. However, a large fraction of the work only showed the morphology and did not characterize the actual performance of these fibers, nor did they test the variability of the fibers and mats from a wide range of processing conditions and resulting structures.

The resistance prediction model was used to confirm the effect of the CNFs on the electrical characteristics of the anodes.

Carbon nanofiber

Using a model that accounts for the effects of intrinsic fiber conductivity including both composition and molecular orientationmat porosity, and the fiber orientation distribution within the mat, calculated mat conductivities are obtained in quantitative agreement with the mat conductivities measured experimentally.

No published details on overall energy costs and efficiency are yet available to be updated. To that purpose, platinum was deposited on oxidized nanostructured carbon materials, i. In Chapter 3 the role of the nature and stability of oxygen surface groups in anchoring and stabilizing platinum particles was investigated.

This may be attributed to the lack of strong covalent bonds between the MWCNTs and the polymer matrix. The percolation behavior of an electrical conduction in nanotubes-polymer composites in a bulk and thin film has been extensively studied for many years [ 8 ].

Thus, this energy barrier may be the activation energy of the polymeric system [ 29 ]. This reinforcement effectively enhanced the electrochemical performance of the carbon nanofibers by recording a specific capacitance of up to F/g at the current density of 1.

A/g, which was approximately three folds more than that of pristine nanofibers. It also retained the capacitance up to % after vigorous charge/discharge cycles.

The ability to directly produce a custom, carbon nanofiber product may allow new advances in composites, hydrogen storage, and air and water filtration.

“The smaller these fibers are, the greater their specific strength gets,” Atwater explained about composites. ELECTROSPUN NANOFIBERS AND THEIR APPLICATIONS IN TRANSPARENT ELECTRODES A Thesis Presented to The Graduate Faculty of The University of Akron. WETTING BEHAVIOR AND CURING KINETICS OF CARBON NANOFIBERS MODIFIED EPOXY RESINS By Yu Fu A thesis submitted in partial fulfillment of the requirements for the degree of.

A micromechanics parametric study was performed to investigate the effect of carbon nanofiber morphology (i.e. hollow vs. solid cross-section), nanofiber waviness, and both nanofiber–resin interphase properties and dimensions on bulk nanocomposite elastic moduli.

Abstract. Vertically aligned carbon nanofibers (VACNFs) have recently become an important tool for biosensor design. Carbon nanofibers (CNF) have excellent conductive and structural properties with many irregularities and defect sites in addition to exposed carboxyl groups throughout their surfaces.

Thesis on carbon nanofibers
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