Producing of Carbon Fibers from Commercial Viscose Fibers

2019 ◽  
Vol 889 ◽  
pp. 58-64 ◽  
Author(s):  
Huu Son Nguyen ◽  
Le Hoang Vu ◽  
Van Cuong Pham ◽  
Xuan Thao La ◽  
Thai Hung Le
Keyword(s):  
Carbon Content ◽  
Carbon Fibers ◽  
Xrd Analysis ◽  
Carbonization Temperature ◽  
Hydrogen Phosphate ◽  
Heating Rates ◽  
Air Atmosphere ◽  
Viscose Fibers ◽  
Gas Atmosphere ◽  
Sem Imaging

In this work, commercial Viscose fibers (cellulosic based precursor) were used for making carbon fibers. The experimental procedures include two main steps: Stabilization in air atmosphere and Carbonization in inert gas atmosphere. In the first step, the Viscose fibers are stabilized with the catalyst of mixture urea/diamonium hydrogen phosphate in air at temperature of 250 °C. The stabilized fibers are then carbonized in argon at heating rates of 3 °C.min-1 (below 600 °C) and 5 °C.min-1 (above 600 °C). Ultimate carbonization temperature is 1200 °C. Commercial Viscose fibers possessed carbon content about 40 wt% and fiber dimension is approximately 18 μm. After carbonization, obtained fibers have carbon content above 94 wt% and diameter of about 8μm. The Thermogravimetry Analysis (TGA), Carbon analysis, SEM imaging and XRD analysis are used for this study.

scholarly journals Carbon Fiber Production from Electrospun Sulfur Free Softwood Lignin Precursors

2017 ◽  
Vol 12 (4) ◽  
pp. 155892501701200 ◽  
Author(s):  
Samira Aslanzadeh ◽  
Behzad Ahvazi ◽  
Yaman Boluk ◽  
Cagri Ayranci
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
Structural Characteristics ◽  
Morphological Characteristics ◽  
Carbonization Temperature ◽  
Purification Process ◽  
Fiber Morphology ◽  
Heating Rates ◽  
Fiber Production

In this study, a sulfur-free softwood lignin (SFSL) was electrospun to form bead-free fibers. The fibers were evaluated as potential precursors for carbon fiber production. Higher heating rates of thermostabilization caused afused fiber morphology. The lignin purification process also affected the quality of the SFSL-based carbon fibers. Therefore, the yield, morphological characteristics, structural characteristics, electrical conductivity and mechanical properties of the carbon fibers were evaluated. At higher carbonization temperatures crystalline carbon fibers were formed. As a result, as the carbonization temperature increased, the conductivity of SFSL-based carbon fibers also increased.

scholarly journals Determination of the Kinetics and Thermodynamic Parameters of Lignocellulosic Biomass Subjected to the Torrefaction Process

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7877
Author(s):  
Maja Ivanovski ◽  
Aleksandra Petrovic ◽  
Irena Ban ◽  
Darko Goricanec ◽  
Danijela Urbancl
Keyword(s):  
Carbon Content ◽  
Isoconversional Methods ◽  
Conversion Degree ◽  
Heating Rates ◽  
Miscanthus X Giganteus ◽  
Main Method ◽  
Air Atmosphere ◽  
Solid Biofuels ◽  
Lignocellulosic Feedstocks

The torrefaction process upgrades biomass characteristics and produces solid biofuels that are coal-like in their properties. Kinetics analysis is important for the determination of the appropriate torrefaction condition to obtain the best utilization possible. In this study, the kinetics (Friedman (FR) and Kissinger–Akahira–Sunose (KAS) isoconversional methods of two final products of lignocellulosic feedstocks, miscanthus (Miscanthus x giganteus) and hops waste (Humulus Lupulus), were studied under different heating rates (10, 15, and 20 °C/min) using thermogravimetry (TGA) under air atmosphere as the main method to investigate. The results of proximate and ultimate analysis showed an increase in HHV values, carbon content, and fixed carbon content, followed by a decrease in the VM and O/C ratios for both torrefied biomasses, respectively. FTIR spectra confirmed the chemical changes during the torrefaction process, and they corresponded to the TGA results. The average Eα for torrefied miscanthus increased with the conversion degree for both models (25–254 kJ/mol for FR and 47–239 kJ/mol for the KAS model). The same trend was noticed for the torrefied hops waste samples; the values were within the range of 14–224 kJ/mol and 60–221 kJ/mol for the FR and KAS models, respectively. Overall, the Ea values for the torrefied biomass were much higher than for raw biomass, which was due to the different compositions of the torrefied material. Therefore, it can be concluded that both torrefied products can be used as a potential biofuel source.

scholarly journals Supercapacitor Electrodes from Viscose-Based Activated Carbon Fibers: Significant Yield and Performance Improvement Using Diammonium Hydrogen Phosphate as Impregnating Agent

2020 ◽  
Vol 6 (2) ◽  
pp. 17
Author(s):  
Stefan Breitenbach ◽  
Alexander Lumetzberger ◽  
Mathias Andreas Hobisch ◽  
Christoph Unterweger ◽  
Stefan Spirk ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Carbon Fibers ◽  
High Performance ◽  
Electrode Materials ◽  
High Energy ◽  
Activated Carbon Fibers ◽  
Hydrogen Phosphate ◽  
Diammonium Hydrogen Phosphate ◽  
Viscose Fibers ◽  
Diammonium Hydrogen

Viscose fibers were impregnated with different concentrations of diammonium hydrogen phosphate (DAHP), carbonized, activated, and tested as high-performance electrode materials for supercapacitors. The yield of these activated carbon fibers (ACFs) could be increased by a factor of 14 by using DAHP compared to ACF without impregnation. These specific activation procedures yielded a high specific surface area of more than 2700 m2·g−1 with a pore size distribution (PSD) suitable for use as a supercapacitor electrode. The electrode materials were implemented in symmetric supercapacitors using TEMA BF4 as electrolyte and cyclic voltammetry measurements showed high specific capacitances of up to 167 F·g−1. Furthermore, the devices showed high energy densities of up to 21.4 W·h·kg−1 and high-power densities of up to 8.7 kW·kg−1. The supercapacitors featured high capacity retention (96%) after 10,000 cycles. These results show that ACFs made of viscose fibers, previously impregnated with DAHP, can be used as high-performance electrodes in supercapacitors for energy storage applications.

Mechanical and Microwave Dielectric Properties of Csf/Si3N4 Composites

2007 ◽  
Vol 546-549 ◽  
pp. 1661-1664
Author(s):  
Xiao Yan Wang ◽  
Fa Luo ◽  
Dong Mei Zhu ◽  
Wan Cheng Zhou ◽  
Hong Huan Wu
Keyword(s):  
Carbon Fibers ◽  
Microwave Dielectric Properties ◽  
Xrd Analysis ◽  
Network Analyzer ◽  
Hot Press ◽  
Frequency Range ◽  
The Real ◽  
Microwave Dielectric ◽  
Hot Press Sintering ◽  
Sintering Method

Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power, short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 was almost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed that special network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, and fracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% the carbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at a frequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of the permittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbon fibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of 9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands.

Reduction of Gd6UO12 for the Synthesis of Gd6UO11

2013 ◽  
Vol 1514 ◽  
pp. 151-156
Author(s):  
Darío Pieck ◽  
Lionel Desgranges ◽  
Yves Pontillon ◽  
Pierre Matheron
Keyword(s):  
Heat Treatment ◽  
Xrd Analysis ◽  
Decomposition Products ◽  
Air Atmosphere ◽  
Reducing Conditions ◽  
Reducing Environment

ABSTRACTIn the present work, we focus on δ-Gd6UO12 phase and its stability under reducing conditions. This later point is interesting regarding reducing environment that could exist in some nuclear storage sites and that could possibly degrade δ–compounds. A polycrystalline δ-Gd6UO12 sample was prepared by sintering cubic-Gd2O3 and UO2 mixed powders under an air atmosphere. The resulting pellets were then characterized and reduced by heat treatment under an Ar with H2 5% atmosphere. XRD analysis of the sample after reduction did not confirm the reduction into Gd6UO11 but a decomposition of the δ-compound. Preliminary characterizations of these decomposition products are presented.

Optimization of carbon coatings on LiFePO4: Carbonization temperature and carbon content

2010 ◽  
Vol 503 (2) ◽  
pp. 370-374 ◽  
Author(s):  
Xiaoke Zhi ◽  
Guangchuan Liang ◽  
Li Wang ◽  
Xiuqin Ou ◽  
Limin Gao ◽  
...  
Keyword(s):  
Carbon Content ◽  
Carbonization Temperature ◽  
Carbon Coatings

Effect of Ti Addition on Oxidation Behavior and Area Specific Resistance of Fe-20Cr Alloys for SOFC Interconnects

2014 ◽  
Vol 660 ◽  
pp. 249-253 ◽  
Author(s):  
Zaka Ruhma ◽  
Asep Ridwan Setiawan ◽  
Aditianto Ramelan ◽  
Rochim Suratman
Keyword(s):  
Oxidation Behavior ◽  
Specific Resistance ◽  
Parabolic Rate Constant ◽  
Xrd Analysis ◽  
Oxidation Rates ◽  
Air Atmosphere ◽  
Ti Alloys ◽  
Initial Stage ◽  
Area Specific Resistance ◽  
Ti Addition

In this work, the oxidation behavior of Fe-20wt.%Cr alloys with different titanium contents: 0, 0.5, and 1 wt.% are studied as a function of time in air atmosphere. The samples were isothermally oxidized at 700°C for 24, 48, and 96 h in a box furnace. The area specific resistance of oxides formed at the alloys surface during oxidation is measured by four-point probe methods at 700°C for 24 h. For Ti containing alloys, surface morphology observation by SEM shows that a few of TiO2 particles formed on the top of Cr2O3 scales. Continous TiO2 layer was not formed at the alloys surface after oxidation. XRD analysis on the oxide scales of Fe-20Cr-Ti alloys confirms that Cr2O3 and TiO2 oxide formed on the alloys. Ti addition into the alloys increases the oxidation rates of alloys at the initial stages. Oxidation behavior of Fe-20Cr-0.5Ti and Fe-20Cr-1Ti alloys showed two regimes. The parabolic rate constant, kp (in gr2/cm4s) were 1.57 x 10-13 and 3.08 x 10-13 respectively for initial stage of oxidation then changed to-9 x 10-15 and-3 x 10-14 respectively for the remainder of the test. ASR measurement shows that the presence of Ti in the alloys decreases the electrical resistance up to 60%. Ti addition into Fe-Cr alloys affect the oxide growth rate and increase the conductivity of Cr2O3 scales.

scholarly journals SYNTHESIS AND INVESTIGATION OF THERMOSTATABILITIVE ACTION ON POLYSTYRENE OF NEW METHACRYLIC MONOMERS BASED ON AURONE

2018 ◽  
pp. 64-67
Author(s):  
N. Iukhymenko ◽  
O. Kharchenko ◽  
V. Smokal ◽  
А. Kolendo
Keyword(s):  
Condensation Reaction ◽  
Internal Standard ◽  
Heating Rates ◽  
Thermogravimetric Analyzer ◽  
Air Atmosphere ◽  
Sample Weight Loss ◽  
Material Sample ◽  
Methacrylic Monomers ◽  
Dta Curves ◽  
Modified Polystyrene

In this work, 6-hydroxy- and 4'-hydroxyaurones were synthesized by condensation reaction of 6-hydroxybenzofuran-3-one with benzaldehyde and benzofuran-3-one with 4-hydroxybenzaldehyde. Methacrylic monomers – (2Z)-6-methacryloxy-2-(4-R-benzylidene)-1-benzofuran-3-(2H)-one and a new 4-[(Z)-(3-oxo-1-benzofuran-2-(3H)ilidene)methyl]phenyl-2-methyl acrylate were obtained by acylation with the methacryloyl chloride in the presence of triethylamine as HCl acceptor at the temperature 0–5°C. These monomers were synthesized to create special purpose polymers. New methacrylic derivatives are not deeply painted and stable in air crystalline monomers. The structure of the synthesized compounds was confirmed by spectral methods. 1H NMR (400 MHz) spectra were recorded on a Mercury (Varian) 400 spectrometer with tetramethylsilane as internal standard in DMSO-d6. The intrachain thermostabilizing effect of these monomers on the polystyrene destruction processes was studied. Polystyrene and its modified samples were obtained by radical thermoinitiated polymerization (initiator – azo-bis-isobutyronitrile – 1 mass percent) in ethyl acetate at the temperature 78°C during 16 hours. In a case modified samples, 3 mol percent of aurone containing monomers were added. Destruction of modified polystyrene was studied by using dynamic thermogravimetric analysis. Destruction of modified polystyrene was carried out in a Simultaneous Differential Thermogravimetric Analyzer which combines a heat-flux type DTA with a TGA (Shimadzu, DTG-60, Japan). Simultaneous TG, DTG and DTA curves were obtained and sample weight loss as functions of time and temperature were recorded continuously under dynamic conditions. Sintered a-alumina was used as the reference material. Sample with mass of 4 mg was inserted directly into platin crucible and temperature was ramped from 20 to 600°C. The heating rates were controlled at 10°C/min. Experiments were performed under an air atmosphere. It was established, that the investigated additives covalently attached to the polystyrene are inhibited the polystyrene destruction processes. Moreover, the additive with the methacrylic group in 6-position of the aurone is significantly more efficient than with the methacrylic group in 4’- position. It has been shown that samples of modified polystyrene by the applications of 4'-methacryloxy aurone and 6-methacryloxy aurone are more thermostable than the industrial sample of polystyrene of brand STYRON (Switzerland). It was shown that the temperature of 10% of the mass loss of modified samples is higher on 14–34 degrees than for the sample of polystyrene of brand STYRON. Thus, the new additives could be proposed for thermostabilizing of polystyrene production.

Lignin-based carbon fibers for renewable and multifunctional lithium-ion battery electrodes

Holzforschung ◽  
2018 ◽  
Vol 72 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Andrzej P. Nowak ◽  
Johan Hagberg ◽  
Simon Leijonmarck ◽  
Hannah Schweinebarth ◽  
Darren Baker ◽  
...  
Keyword(s):  
Lithium Ion Battery ◽  
Carbon Fibers ◽  
Negative Electrode ◽  
Lithium Ion ◽  
Renewable Resource ◽  
Carbonization Temperature ◽  
Mechanical Integrity ◽  
Different Temperatures ◽  
Strength And Stiffness ◽  
Softwood Kraft Lignin

AbstractLignin-based carbon fibers (LCFs) from the renewable resource softwood kraft lignin were synthesized via oxidative thermostabilization of pure melt-spun lignin and carbonization at different temperatures from 1000°C to 1700°C. The resulting LCFs were characterized by tensile testing, scanning electron microscopy (SEM), X-ray diffraction (XRD) and confocal Raman spectroscopy. The microstructure is mainly amorphous carbon with some nanocrystalline domains. The strength and stiffness are inversely proportional to the carbonization temperature, while the LCFs carbonized at 1000°C exhibit a strength of 628 MPa and a stiffness of 37 GPa. Furthermore, the application potential of LCFs was evaluated as negative electrodes in a lithium-ion battery (LIB) by electrochemical cycling at different current rates in a half-cell setup. The capacity drops with the carbonization temperature and the LCFs carbonized at 1000°C have a capacity of 335 mAh g−1. All LCFs showed good cycling stability. Because of the mechanical integrity and conductivity of the LCFs, there is no need to apply current collectors, conductive additives or binders. The advantage is an increased gravimetric energy density compared to graphite, which is the most common negative electrode material. LCFs show a promising multifunctional behavior, including good mechanical integrity, conductivity and an ability to intercalate lithium for LIBs.

Sign in / Sign up

Export Citation Format

Share Document