• Title/Summary/Keyword: carbon fibers

Search Result 842, Processing Time 0.02 seconds

Fabrication and Applications of Carbon Nanotube Fibers

  • Choo, Hungo;Jung, Yeonsu;Jeong, Youngjin;Kim, Hwan Chul;Ku, Bon-Cheol
    • Carbon letters
    • /
    • v.13 no.4
    • /
    • pp.191-204
    • /
    • 2012
  • Carbon nanotubes (CNTs) have exceptional mechanical, electrical, and thermal properties compared with those of commercialized high-performance fibers. For use in the form of fabrics that can maintain such properties, individual CNTs should be held together in fibers or made into yarns twisted out of the fibers. Typical methods that are used for such purposes include (a) surfactant-based coagulation spinning, which injects a polymeric binder between CNTs to form fibers; (b) liquid-crystalline spinning, which uses the nature of CNTs to form liquid crystals under certain conditions; (c) direct spinning, which can produce CNT fibers or yarns at the same time as synthesis by introducing a carbon source into a vertical furnace; and (d) forest spinning, which draws and twists CNTs grown vertically on a substrate. However, it is difficult for those CNT fibers to express the excellent properties of individual CNTs as they are. As solutions to this problem, post-treatment processes are under development for improving the production process of CNT fibers or enhancing their properties. This paper discusses the recent methods of fabricating CNT fibers and examines some post-treatment processes for property enhancement and their applications.

Microstructural changes of polyacrylonitrile-based carbon fibers (T300 and T700) due to isothermal oxidation (1): focusing on morphological changes using scanning electron microscopy

  • Oh, Seong-Moon;Lee, Sang-Min;Kang, Dong-Su;Roh, Jae-Seung
    • Carbon letters
    • /
    • v.18
    • /
    • pp.18-23
    • /
    • 2016
  • Polyacrylonitrile (PAN)-based carbon fibers have high specific strength, elastic modulus, thermal resistance, and thermal conductivity. Due to these properties, they have been increasingly widely used in various spheres including leisure, aviation, aerospace, military, and energy applications. However, if exposed to air at high temperatures, they are oxidized, thus weakening the properties of carbon fibers and carbon composite materials. As such, it is important to understand the oxidation reactions of carbon fibers, which are often used as a reinforcement for composite materials. PAN-based carbon fibers T300 and T700 were isothermally oxidized in air, and microstructural changes caused by oxidation reactions were examined. The results showed a decrease in the rate of oxidation with increasing burn-off for both T300 and T700 fibers. The rate of oxidation of T300 fibers was two times faster than that of T700 fibers. The diameter of T700 fibers decreased linearly with increasing burn-off. The diameter of T300 also decreased with increasing burn-off but at slower rates over time. Cross-sectional observations after oxidation reactions revealed hollow cores in the longitudinal direction for both T300 and T700 fibers. The formation of hollow cores after oxidation can be traced to differences in the fabrication process such as the starting material and final heat treatment temperature.

Compressional Behavior of Carbon Nanotube Reinforced Mesophase Pitch-based Carbon Fibers

  • Ahn Young-Rack;Lee Young-Seak;Ogale A.A.;Yun Chang-Hun;Park Chong-Rae
    • Fibers and Polymers
    • /
    • v.7 no.1
    • /
    • pp.85-87
    • /
    • 2006
  • The tensile-recoil compressional behavior of the carbon nanotube reinforced mesophase pitch (MP)-based composite carbon fibers (CNT-re-MP CFs) was investigated by using Instron and SEM. The CNT-re-MP CFs exhibited improved, or at least equivalent, compressive strength as compared with commercial MP-based carbon fibers. Particularly, when CNT of 0.1 wt% was reinforced, the ratios of recoil compressive strengths to tensile strength of CNT-re-MPCFs were much higher (the difference is at least 10 % or higher) than those for the commercial counterparts and even than those for PAN-based commercial carbon fibers. FESEM micrographs showed somewhat different fractography from that of a typical shear failure as the CNT content increased.

A Study on Stabilization and Mechanical Properties of Polyacrylonitrile-based Fiber with Itaconic acid (이타콘산을 함유한 폴리아크릴로니트릴계 전구체섬유의 열안정화 및 그 물성에 관한 연구)

  • 신익기;이신희;박수민
    • Textile Coloration and Finishing
    • /
    • v.15 no.2
    • /
    • pp.76-85
    • /
    • 2003
  • In this study, a continuous stabilization process is used to make high-performance carbon fiber from polyacrylonitrile(PAM)-based fibers. The effect of oxygen content of PAN-based fiber on the stabilization process and the properties of the resultant carbon fibers is investigated. In order to research the progress of stabilization reaction FT-IR, elemental analysis, density, DSC, etc are used. Stabilization is carried out in air atmosphere from the 200 to $300^\circ{C}$ temperature range. An increase of PAN-based fibers diameter reduces the oxygen content during the continuous stabilization process. A higher oxygen content increase the density, tensile strength and modulus in the resultant carbon fibers. The most appropriate oxygen content in the stabilized fiber should be about 12%. Fibers having more than 2% oxygen content yield carbon fibers with inferior properties. Those carbon fibers also have sufficient commercial availability.

Effects of Sizing Treatment of Carbon Fibers on Mechanical Interfacial Properties of Nylon 6 Matrix Composites (탄소섬유의 사이징처리가 탄소섬유/나일론6 복합재료의 기계적 계면 특성에 미치는 영향)

  • Park, Soo-Jin;Choi, Woong-Ki;Kim, Byung-Joo;Min, Byung-Gak;Bae, Kyong-Min
    • Elastomers and Composites
    • /
    • v.45 no.1
    • /
    • pp.2-6
    • /
    • 2010
  • The sizing treatments of PAN-based carbon fiber surfaces were carried out in order to improve the interfacial adhesion in the carbon fibers/nylon6 composite system. The parameter to characterize the wetting performance and surface free energy of the sized fibers were determined by a contact angle method. The mechanical interfacial properties of the composites were investigated using critical stress intensity factor ($K_{IC}$). The cross-section morphologies of sized CFs/nylon6composites were observed by SEM. As the experimental results, it was observed that silane-based sizing treated carbon fibers showed higher surface free energies than other sizing treatments. In particular, the KIC of the sizing-treated carbon fibers reinforced composites showed higher values than those of untreated carbon fibers-reinforced composites. This result indicated that the increase in the surface free energy of the fibers leads to the improvement of the mechanical interfacial properties of carbon fibers/nylon6 composites.

Carbon Fibers(III): Recent Technical and Patent Trends

  • Seo, Min-Kang;Park, Sang-Hee;Kang, Shin-Jae;Park, Soo-Jin
    • Carbon letters
    • /
    • v.10 no.1
    • /
    • pp.43-51
    • /
    • 2009
  • Carbon fibers are a new breed of high-strength materials. The existence of carbon fiber came into being in 1879 when Edison took out a patent for the manufacture of carbon filaments suitable for use in electric lamps. However, it was in the early 1960s when successful commercial production was started, as the requirements of the aerospace industry for better and lightweight materials became of paramount importance. In recent decades, carbon fibers have found wide applications in commercial and civilian aircraft, along with recreational, industrial, and transportation markets as the price of carbon fiber has come down and technologies have matured. The market for carbon fiber has experienced a good growth in recent years. The growth rate for the last 23years was about 12%. The article reviewed 9,641 Korea, U.S., Japan, Europe patents issued in the carbon fibers in order to offer additional insight for researchers and companies seeking to navigate carbon fiber patent landscape. This article will provide you with all the valuable information and tools you will need to investigate your study successfully within the carbon fiber field. This article also will save you hundreds of hours of your own personal research time and will significantly benefit you in expanding your business in the carbon fiber market.

Effect of Inherent Anatomy of Plant Fibers on the Morphology of Carbon Synthesized from Them and Their Hydrogen Absorption Capacity

  • Sharon, Madhuri;Sharon, Maheshwar
    • Carbon letters
    • /
    • v.13 no.3
    • /
    • pp.161-166
    • /
    • 2012
  • Carbon materials were synthesized by pyrolysis from fibers of Corn-straw (Zea mays), Rice-straw (Oryza sativa), Jute-straw (Corchorus capsularis) Bamboo (Bombax bambusa), Bagass (Saccharum officinarum), Cotton (Bombax malabaricum), and Coconut (Cocos nucifera); these materials were characterized by scanning electron microscope, X-ray diffraction (XRD), and Raman spectra. All carbon materials are micro sized with large pores or channel like morphology. The unique complex spongy, porous and channel like structure of Carbon shows a lot of similarity with the original anatomy of the plant fibers used as precursor. Waxy contents like tyloses and pits present on fiber tracheids that were seen in the inherent anatomy disappear after pyrolysis and only the carbon skeleton remained; XRD analysis shows that carbon shows the development of a (002) plane, with the exception of carbon obtained from bamboo, which shows a very crystalline character. Raman studies of all carbon materials showed the presence of G- and D-bands of almost equal intensities, suggesting the presence of graphitic carbon as well as a disordered graphitic structure. Carbon materials possessing lesser density, larger surface area, more graphitic with less of an $sp^3$ carbon contribution, and having pore sizes around $10{\mu}m$ favor hydrogen adsorption. Carbon materials synthesized from bagass meet these requirements most effectively, followed by cotton fiber, which was more effective than the carbon synthesized from the other plant fibers.

Hydrogen Storage by Carbon Fibers Synthesized by Pyrolysis of Cotton Fibers

  • Sharon, Maheshwar;Sharon, Madhuri;Kalita, Golap;Mukherjee, Bholanath
    • Carbon letters
    • /
    • v.12 no.1
    • /
    • pp.39-43
    • /
    • 2011
  • Synthesis of carbon fibers from cotton fiber by pyrolysis process has been described. Synthesis parameters are optimized using Taguchi optimization technique. Synthesized carbon fibers are used for studying hydrogen adsorption capacity using Seivert's apparatus. Transmission electron microscopy analysis and X-ray diffraction of carbon fiber from cotton suggested it to be very transparent type material possessing graphitic nature. Carbon synthesized from cotton fibers under the conditions predicted by Taguchi optimization methodology (no treatment of cotton fiber prior to pyrolysis, temperature of pyrolysis $800^{\circ}C$, Argon as carrier gas and paralyzing time for 2 h) exhibited 7.32 wt% hydrogen adsorption capacity.

Fabrication and Characterization of Porous Non-Woven Carbon Based Highly Sensitive Gas Sensors Derived by Magnesium Oxide

  • Kim, Yesol;Cho, Seho;Lee, Sungho;Lee, Young-Seak
    • Carbon letters
    • /
    • v.13 no.4
    • /
    • pp.254-259
    • /
    • 2012
  • Nanoporous non-woven carbon fibers for a gas sensor were prepared from a pitch/polyacrylonitrile (PAN) mixed solution through an electrospinning process and their gas-sensing properties were investigated. In order to create nanoscale pores, magnesium oxide (MgO) powders were added as a pore-forming agent during the mixing of these carbon precursors. The prepared nanoporous carbon fibers derived from the MgO pore-forming agent were characterized by scanning electron microscopy (SEM), $N_2$-adsorption isotherms, and a gas-sensing analysis. The SEM images showed that the MgO powders affected the viscosity of the pitch/PAN solution, which led to the production of beaded fibers. The specific surface area of carbon fibers increased from 2.0 to $763.2m^2/g$ when using this method. The template method therefore improved the porous structure, which allows for more efficient gas adsorption. The sensing ability and the response time for the NO gas adsorption were improved by the increased surface area and micropore fraction. In conclusion, the carbon fibers with high micropore fractions created through the use of MgO as a pore-forming agent exhibited improved NO gas sensitivity.

Effect of carbonization temperature and chemical pre-treatment on the thermal change and fiber morphology of kenaf-based carbon fibers

  • Kim, Jin-Myung;Song, In-Seong;Cho, Dong-Hwan;Hong, Ik-Pyo
    • Carbon letters
    • /
    • v.12 no.3
    • /
    • pp.131-137
    • /
    • 2011
  • Kenaf fibers, cellulose-based natural fibers, were used as precursor for preparing kenafbased carbon fibers. The effects of carbonization temperature ($700^{\circ}C$ to $1100^{\circ}C$) and chemical pre-treatment (NaOH and $NH_4Cl$) at various concentrations on the thermal change, chemical composition and fiber morphology of kenaf-based carbon fibers were investigated. Remarkable weight loss and longitudinal shrinkage were found to occur during the thermal conversion from kenaf precursor to kenaf-based carbon fiber, depending on the carbonization temperature. It was noted that the alkali pre-treatment of kenaf with NaOH played a role in reducing the weight loss and the longitudinal shrinkage and also in increasing the carbon content of kenaf-based carbon fibers. The number and size of the cells and the fiber diameter were reduced with increasing carbonization temperature. Morphological observations implied that the micrometer-sized cells were combined or fused and then re-organized with the neighboring cells during the carbonization process. By the pre-treatment of kenaf with 10 and 15 wt% NaOH solutions and the subsequent carbonization process, the inner cells completely disappeared through the transverse direction of the kenaf fiber, resulting in the fiber densification. It was noticeable that the alkali pre-treatment of the kenaf fibers prior to carbonization contributed to the forming of kenaf-based carbon fibers.