• Polymer(Korea)
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• v.24 no.1
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• pp.97-104
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• 2000

PAN-based activated carbon fibers/phenolic resin matrix composites (ACFCs) were manufactured via molding process with oxidized carbon fabrics (plain-type) and phenolic resin (resole-type) compounded by 70 : 30 wt%. The green body (as molded) was submitted to carbonization (at 100$0^{\circ}C$) in an inert environment and activation (at 700, 800, 900 and 100$0^{\circ}C$) in a $CO_2$ environment. In this work, the influence of activation temperatures was investigated in surface properties, such as pH, acid- and base-values by titration method, and in adsorption properties, i.e., specific surface area and pore structures by BET-method of the composites. Also, the pressure drops of the specimens were calibrated by ASTM. As a result, the activation temperature influenced the surface property of ACFCs. When the activation temperature was higher than 90$0^{\circ}C$, the surface was gradually developed in basic nature. And, the evolutions of specific surface area, total pore volume and pore size distribution of ACFCs could be easily confirmed the dependence on the activation temperature. Among them, well-developed pore structure from adsorption characteristics was changed of the ACFCs activated at 90$0^{\circ}C$. Also, the pressure drop was slightly decreased with increasing the temperature due to increasing the burn-off with heat treatment temperature of ACFCs.

• Polymer(Korea)
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• v.25 no.2
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• pp.218-225
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• 2001

The electroless plating of a metallic nickel on PAN-based carbon fiber surfaces was carried out to improve mechanical interfacial properties of the carbon fiber/epoxy resin composites which were unidirectionally fabricated by a prepregging method. In this work, the influence of Ni-P alloy concentration showing brittle-to-ductile transition was investigated on interlaminar shear strength (ILSS) and impact strength of the composites. The surface properties of carbon fibers were also measured by X-ray photoelectron spectroscopy (XPS). As the result, the $O_{ls}$ /$O_{ls}$ ratio or Ni and P amounts were increased with increasing electroless nickel plating time but the ILSS were not significantly improved. However, the impact properties was significantly improved in the presence of Ni-P alloy in the carbon fiber surface, resulting in an increase of the ductility of the composites.

• Magazine of the Korea Concrete Institute
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• v.5 no.4
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• pp.145-155
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• 1993

The results of an experimental study on the manufacture and the mechanical properties of fiber reinforced fly ash$\cdot$lime$\cdot$gypsum composites are presented in this paper. 'The composites using fly ash, lime, and gypsum were prepared with various fibers (PAN-derived and Pitch-derived carbon fiber, alkali-resistance glass fiber) and a small amount of polymer emulsion-styrene butadiene rubber latex (SBR). As the test results show, the manufacturing process technology of fly ash$\cdot$lime$\cdot$gypsum composites was developed and its optimum mix proportions were successfully proposed. And the flexural strength and toughness of fiber reinforced fly ash$\cdot$lime $\cdot$gypsum composites were increased remarkably by fiber contents, but the compressive strength of the composites were influenced by the kinds fiber more than by the fiber contents. Also, the addition of a polymer emulsion to the composites decreased the bulk specific gravity, but the compressive and flexural strength, and the toughness of the composites were not influenced by it, but were considerably improved by increasing fiber contents.

• Composites Research
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• v.15 no.6
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• pp.16-23
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• 2002

In this work, the effect of anodic oxidation on surface characteristics of high strength PAN-based carbon fibers was investigated in mechanical interfacial properties of composites. The surface properties of the carbon fibers were determined by acid-base values, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angles. And their mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical stress intensity factor ($K_{IC}$). As a result, the acidity or the $O_{ls}/C_{ls}$ ratio of carbon fiber surfaces was increased, due to the development of the oxygen functional groups. Consequently, the anodic oxidation led to an increase in surface free energy of the carbon fibers, mainly due to the increase of its specific (or polar) component. The mechanical interfacial properties of the composites, including ILSS and $K_{IC}$, had been improved in the anodic oxidation on fibers. These results were explained that good wetting played an important role in improving the degree of adhesion at interfaces between fibers and epoxy resin matrix.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.81-87
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• 1999

Poly-acrylonitrile (PAN) based carbon fibers were stabilized under various tensions in the presence of air at about $200^{\circ}C$ and sequentially carbonized under some different gas environments in the range of 700 to $1500^{\circ}C$. The prepared carbon fibers were used for rechargeable lithium ion battery anode to investigate preparation parameters effects on electrochemical characteristics. It was found that the tension during stabilization, carbonization temperature and gas atmospheres affect the carbon fiber properties such as conductivity, mechanical strength, surface morphology and diffusion coefficient of lithium ion, which are closely related to the on electrolchemical properties as well as the charge/discharge characteristics.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.602-608
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• 2006

Carbon fiber (CF) reinforced papers using polyacrylonitrile (PAN) based CF and wood pulp were prepared by varying the lengths and the concentrations of CF, and the basis weight of paper to investigate adhesive state between CF and pulp, and physical properties and electrical conductivity of the paper. The reinforcement was caused by physical entanglement and adhesion at the interface of the different fibers rather than by chemical bonds. The tear strength and the thickness of the paper increased as increasing the concentration of CF, while the tensile and the burst strength of the paper decreased. The improved dispersion of CF in the paper was obtained from mixing shorter CF, but the maximum electrical conductivity of the paper was gained from mixing 10 mm chopped CF. The electrical conductivity of the paper increased sharply from 2 wt％ to 8 wt％ of CF showing S-curve, and increased linearly as increasing the basis weight of the paper. Therefore, in order to improve the electrical conductivity and the physical property of the paper, the increase of basis weight of the paper is also important as the increase of CF content in the paper.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.467-474
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• 2007

The palladium and gold nanoparticles containing PAN-based active carbon fiber (ACF) with a high specific surface area were prepared. Using the BET, TEM, FE-SEM, and XPS, their specific surface area and pore volume, pore structure, and the change in surface oxygen groups with time were analyzed and $SO_2$ adsorption performances were investigated. Because of the impregnating process, the micropore volume was mostly decreased from 95.5% to 30.5~43.7% compared with the total pore volume. And the change in surface oxygen groups with time was higher for the metal salt than the nanoparticles. Also, $SO_2$ breakthrough time of PAN-ACFs impregnated with Au nanoparticles and metal salts did not change compared with that of the non-impregnated PAN-ACF. But the PAN-ACF impregnated with Pd nanoparticles (100 ppm) showed good $SO_2$ adsorption performance as the breakthrough time of 880 sec. These results indicated that the $SO_2$ adsorption performance depended on the change in surface oxygen groups with time and the moderate impregnation of Pd nanoparticles on the PAN-ACF caused the increase in the $SO_2$ adsorption performance by a catalytic action.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.339-348
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• 1994

The study has been conducted to know ablation microstructures and characteristics in carbon /phenolic composites. Ablation properties depend on mole fraction of $H_2O$ and $C0_2$ gas which were produced by reaction between propellant and oxidizer. However, the results of this study shown that the ablation also depended on weaving structure, density of fabric, and tow size of carbon fiber. 3K 8HS fabric showed superior ablation resistance to others, 3K twill and 12K 8HS fabric structures.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.287-294
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• 1994

PAN-based carbon fiber roving and fabric were heat treated at the temperature of $2170^{\circ}C$. Using non-heat treated and heat treated fabric, greenbodies of CFRP and GFRP were manufactured in the Autoclave. After the analysis of heat treated and non-heat treated carbon fiber roving and two types of greenbodies, the variations of physical and mechanical properties of carbon fibers and greenbodies with heat treatment were studied. Observing the cross-section of carbon fiber with SEM, we knew the diameter of carbon fiber was decreased from 6.8gm to 6.4p1. The results of TGA showed that the oxidation resistence was enhanced after heat treatment. The tensile strength of carbon fiber was decreased from (3.11$\pm 0.32)\times 10^3$ MPa to (1.87$\pm 0.26)\times 10^3$MPa, but tensile modulus was increased from (1.94$\pm 0.06)\times 10^5$ MPa to (2.02$\pm 0.11)\times 10^5$MPa after heat treatment. The interlaminar shear strengths of CFRP and GFRP were 148.8$\pm$1.6Mpa and 82.2$\pm$1.1Mpa, respectively. Torch test showed that CFRP was abraded smoothly but GFRP was delaminated.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.138-143
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• 2011

To investigate the electromagnetic interference shielding efficiency (EMI SE) property based on heat treatment effects of carbon fibers in various temperatures, the polyacrilonitrle-based carbon fibers were prepared by electrospinning method and treated at 1073, 1323, 1873 and 2573 K. The surface morphology of carbon fibers was investigated by using FE-SEM and the carbon crystallization was studied by Raman spectroscopy based on effects of reaction temperatures. The electrical conductivity was obtained by measuring the surface resistance with four probe method on carbon crystallization. The permittivity, permeability and EMI SE were investigated by using S-parameter in the range of 800~4500 MHz. In case of carbon fibers treated at 2573 K, the improved carbon crystallization was confirmed by Raman spectrum and the enhanced electrical conductivity showing 54.7 S/cm was also observed. The permittivity was dramatically improved by factor of 4 based on effect of high reaction temperature. Eventually, the highly improved EMI SE value was obtained showing around 41.7 dB.