Effect of Reaction Temperature on the Morphology of Carbon Nanofibers

2011 ◽  
Vol 306-307 ◽  
pp. 1247-1251
Author(s):  
Li Yan Yu ◽  
Li Na Sui ◽  
Hong Zhou Dong ◽  
Li Feng Dong
Keyword(s):  
Carbon Nanofibers ◽  
Nickel Catalyst ◽  
Carbon Fibers ◽  
Low Temperatures ◽  
Critical Parameter ◽  
Catalytic Pyrolysis ◽  
Nickel Nanoparticles ◽  
Catalyst Nanoparticles ◽  
Nickel Particles ◽  
Size And Morphology

Carbon nanofibers with various morphologies were synthesized by the catalytic pyrolysis of acetylene using nickel catalyst nanoparticles at different reaction temperatures. Experimental results demonstrate that temperature is a critical parameter for controlling the size and morphology of carbon fibers. Twin coiled fibers and linearly bifurcating fibers emanating from nickel particles were formed at 400 °C; whereas, only linear carbon nanofibers were obtained at reaction temperatures of 450 °C, 500 °C, and 550 °C. At low temperatures, nickel nanoparticles remain in the middle of two fibers, while nickel particles are positioned at one end of the linear fibers at high temperatures.

Cytocompatibility of Carbon Nanofiber Materials for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Carbon Fiber ◽  
Surface Energy ◽  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Carbon Nanofiber ◽  
Fiber Composite ◽  
Scar Tissue ◽  
Pc 12 Cells ◽  
Low Surface Energy ◽  
Poly Carbonate

AbstractSince the cytocompatibility of carbon nanofibers with respect to neural applications remains largely uninvestigated, the objective of the present in vitro study was to determine cytocompatibility properties of formulations containing carbon nanofibers. Carbon fiber substrates were prepared from four different types of carbon fibers, two with nanoscale diameters (nanophase, or less than or equal to 100 nm) and two with conventional diameters (or greater than 200 nm). Within these two categories, both a high and a low surface energy fiber were investigated and tested. Astrocytes (glial scar tissue-forming cells) and pheochromocytoma cells (PC-12; neuronal-like cells) were seeded separately onto the substrates. Results provided the first evidence that astrocytes preferentially adhered on the carbon fiber that had the largest diameter and the lowest surface energy. PC-12 cells exhibited the most neurites on the carbon fiber with nanodimensions and low surface energy. These results may indicate that PC-12 cells prefer nanoscale carbon fibers while astrocytes prefer conventional scale fibers. A composite was formed from poly-carbonate urethane and the 60 nm carbon fiber. Composite substrates were thus formed using different weight percentages of this fiber in the polymer matrix. Increased astrocyte adherence and PC-12 neurite density corresponded to decreasing amounts of the carbon nanofibers in the poly-carbonate urethane matrices. Controlling carbon fiber diameter may be an approach for increasing implant contact with neurons and decreasing scar tissue formation.

scholarly journals Dehumidified Air-Assisted Spray-Drying of Cloudy Beetroot Juice at Low Temperature

2021 ◽  
Vol 11 (14) ◽  
pp. 6578
Author(s):  
Aleksandra Jedlińska ◽  
Alicja Barańska ◽  
Dorota Witrowa-Rajchert ◽  
Ewa Ostrowska-Ligęza ◽  
Katarzyna Samborska
Keyword(s):  
Particle Size ◽  
Physicochemical Properties ◽  
Spray Drying ◽  
Low Temperatures ◽  
Beetroot Juice ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Tapped Density ◽  
Lower Loss ◽  
Better Than

This paper discusses the physicochemical properties of powders obtained by spray drying of cloudy beetroot juice, using dehumidified air in variants with or without carriers. The inlet air temperature was 130 °C or 90 °C, and the addition of the carriers was at a ratio of juice to carrier solids of 3:2. In the obtained powders, the following physicochemical properties were determined: water content and water activity, apparent density, loose and tapped density, porosity, flowability, particle size and morphology, and the content and retention of betalains. It was possible to dry cloudy beetroot juice without the use of carriers at low temperatures (90 or 130 °C). The 100% beetroot powders were characterized by satisfactory physicochemical properties, often better than those with carriers (including lower hygroscopicity and higher color saturation and yield). A lower loss of betalains was found for the powders with the addition of carriers. The best process yields were obtained for the powder without carriers at 130 °C and 90 °C.

Properties of Carbon Nanofibers Prepared from Polyacrylonitrile/Poly(methyl Methacrylate) Blend

2009 ◽  
Vol 79-82 ◽  
pp. 353-356
Author(s):  
Wei Pan ◽  
Yan Chen ◽  
Xiao Wei He
Keyword(s):  
Methyl Methacrylate ◽  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Nitrogen Atmosphere ◽  
Wet Spinning ◽  
X Ray Diffraction ◽  
X Ray ◽  
Poly Methyl Methacrylate ◽  
Graphite Crystallite ◽  
Raman Microspectrometry

The polyacrylonitrile(PAN)/poly (methyl methacrylate)(PMMA) blend fibers were prepared by wet-spinning technique and carbonized over the temperature range of 400-1000°C in nitrogen atmosphere. After carbonization of the blend fibers, the PMMA component removed and the PAN component left in the form of carbon nanofibers. Morphology of the carbon nanofibers were investigated via scanning electron microscopy (SEM), and the carbonization behavior of the fibers were examined via x-ray diffraction (XRD), Raman microspectrometry. The optimal condition made carbon fibers with great L/D ratio and diameter less than 200 nm. XRD and Raman spectra shows that the PAN/PMMA blend fibers treated at 600°C produced some graphite crystallite.

scholarly journals Chemical Analysis of Airbrushed Nickel Nanoparticles for Large-Area Growth of Vertically Aligned Carbon Nanofibers on Metal Surfaces

2013 ◽  
Vol 19 (S2) ◽  
pp. 1572-1573
Author(s):  
A. Oni ◽  
R. White ◽  
M. Sarac ◽  
B. Anderson ◽  
R. Pearce ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Carbon Nanofibers ◽  
Metal Surfaces ◽  
Nickel Nanoparticles ◽  
Large Area ◽  
Area Growth ◽  
Vertically Aligned ◽  
Vertically Aligned Carbon Nanofibers

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Direct conversion of carbon nanofibers and nanotubes into diamond nanofibers and the subsequent growth of large-sized diamonds

Nanoscale ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 2238-2248 ◽  
Author(s):  
J. Narayan ◽  
A. Bhaumik ◽  
R. Sachan ◽  
A. Haque ◽  
S. Gupta ◽  
...  
Keyword(s):  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Laser Annealing ◽  
Pulsed Laser ◽  
Direct Conversion ◽  
Ambient Conditions ◽  
Subsequent Growth ◽  
Pulsed Laser Annealing ◽  
Annealing Method

We report a pulsed laser annealing method to convert carbon fibers and nanotubes into diamond fibers under ambient conditions.

scholarly journals Photoconductivity of activated carbon fibers

1991 ◽  
Vol 6 (5) ◽  
pp. 1040-1047 ◽  
Author(s):  
K. Kuriyama ◽  
M.S. Dresselhaus
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Carbon Fibers ◽  
Low Temperatures ◽  
Room Temperature ◽  
High Surface ◽  
Localized States ◽  
Activated Carbon Fibers ◽  
Disordered Carbon ◽  
Increasing Temperature

The conductivity and photoconductivity are measured on a high-surface-area disordered carbon material, i.e., activated carbon fibers, to investigate their electronic properties. This material is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000–2000 m2/g. Our preliminary thermopower measurements show that the dominant carriers are holes at room temperature. The x-ray diffraction pattern reveals that the microstructure is amorphous-like with Lc ≃ 10 Å. The intrinsic electrical conductivity, on the order of 20 S/cm at room temperature, increases by a factor of several with increasing temperature in the range 30–290 K. In contrast, the photoconductivity in vacuum decreases with increasing temperature. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The recombination kinetics changes from a monomolecular process at room temperature to a bimolecular process at low temperatures, indicative of an increase in the photocarrier density at low temperatures. The high density of localized states, which limits the motion of carriers and results in a slow recombination process, is responsible for the observed photoconductivity.

Preparation of carbon nanofibers over carbon nanotube-nickel catalyst in propylene decomposition

2007 ◽  
Vol 42 (12) ◽  
pp. 4240-4244 ◽  
Author(s):  
Yun Zhao ◽  
Chunhua Li ◽  
Kefu Yao ◽  
Ji Liang
Keyword(s):  
Carbon Nanotube ◽  
Carbon Nanofibers ◽  
Nickel Catalyst

Synthesis and Characterization of Exotic Carbon Fibers with Branched Spurs Using Nickel Catalyst Precursor

2013 ◽  
Vol 645 ◽  
pp. 3-9
Author(s):  
Qian Zhang ◽  
Qiu Xiang Wang ◽  
Hong Zhou Dong ◽  
Li Feng Dong
Keyword(s):  
Electron Microscopy ◽  
Nickel Catalyst ◽  
Carbon Fibers ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Catalyst Precursor ◽  
X Ray ◽  
Transmission Electron

In this paper, we have synt hesized exotic carbon fibers with branched spurs by a chemical vapor deposition method using nickel catalyst precursor at 600 °C. No catalyst particles were found at the base of the carbon spurs, suggesting that the ni ckel catalyst particles, which were decomposed from the nickel catalyst precursor, facilitated the growth of the carbon fibers but not the spurs. The formation of the spurs resulted from the fluctuation of the carbon source gas acetylene flow. The samples were characterized by field emission sc anning electron microscopy, transmission electron microscopy, and X-ray powder diffraction.

Use of Graphite Nanofibers as a Novel Catalyst Support Medium for Hydrogenation Reactions

1996 ◽  
Vol 454 ◽  
Author(s):  
C. Park ◽  
N. M. Rodriguez ◽  
R. T. K. Baker
Keyword(s):  
Carbon Nanofibers ◽  
Carbon Nanofiber ◽  
Catalyst Support ◽  
Catalytic Behavior ◽  
Graphite Nanofibers ◽  
Nickel Particles ◽  
Support Medium ◽  
Different Types ◽  
Hydrogenation Reactions ◽  
Novel Catalyst

ABSTRACTIn this investigation we elected to use the hydrogenation of 1-butene as probe reactions in an attempt to monitor any possible changes in catalytic behavior resulting from supporting 5 wt.% nickel on different types of carbon nanofibers compared to the performance of the same metal loading on more traditional carriers, including γ-Al2O3 and active carbon. In all cases the carbon nanofiber supported nickel particles are found to exhibit superior activity and significant changes in selectivity to that found from the same metal supported on traditional carriers.

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