• Fibers and Polymers
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• 제5권1호
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• pp.31-38
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• 2004

In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.

• Carbon letters
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• 제16권3호
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• pp.219-221
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• 2015

In order to study the impact of atmosphere during electron beam irradiation (EBI) of polyacrylonitrile (PAN) precursor fibers, the latter were stabilized by EBI in both air and oxygen atmospheres. Gel-fraction determination indicated that EBI-stabilization under an oxygen atmosphere leads to an enhanced cyclization in the PAN fibers. In the Fourier-transform infrared spectroscopy analysis, the PAN fibers stabilized by EBI under an oxygen atmosphere exhibited a greater decrease in the peak intensity at 2244 cm⁻¹ (C≡N vibration) and a greater increase in the peak intensity at 1628 cm⁻¹ (C=N absorption) than the corresponding PAN fibers stabilized under an air atmosphere. From the X-ray diffraction analysis it was found that oxygen uptake in PAN fibers leads to an increase in the amorphous region, produced by cyclization.

• 폴리머
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• 제25권4호
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• pp.575-586
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• 2001

안정화 폴리아크릴로니트릴(PAN) 섬유는 탄소섬유 제조에서 요구되는 온도보다 낮은 조건에서 여러 가지 열처리공정 인자에 따라 다른 물성을 갖는 준탄소섬유로 변환될 수 있다. 최근의 초기연구 결과에 의하면 약 1100$^{\circ}C$ 부근에서 적절한 준탄화공정은 준탄소섬유의 물성과 준탄소섬유/고분자 복합재료의 물성에 매우 중요하게 작용하는 것으로 조사되었다. 따라서, 본 연구의 목적은 안정화 PAN 섬유를 이용하여 여러 준탄화공정을 통해 준탄소섬유를 제조하고 그 물성을 조사하는 것이다. 준탄소공정은 800$^{\circ}C$까지의 저온영역과 1000$^{\circ}C$ 이상의 고온영역으로 나누어 행하였으며, 최종 준탄화온도, 승온속도, 체류시간, 승온단계, 분위기가스 등을 변화시켜가며 얻어진 준탄소섬유에 대한 화학조성, 물리적 특성, 열안정성, 미세구조, 기계적 특성 및 전기저항성을 조사하였다. 각 조건에서 얻어진 준탄소섬유에 대한 결과는 열처리전 안정화 PAN 섬유와 상업용 PAN계 탄소섬유의 물성과 비교 분석하였다. 본 연구의 결과는 조사된 물성이 주어진 여러 가지 준탄화공정 인자에 크게 의존하였음을 보여주었다.

• Carbon letters
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• 제12권1호
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• pp.26-30
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• 2011

For polyacrylonitrile (PAN) based carbon fiber (CF) process, we developed a lab scale wet spinning line and a continuous tailor-made stabilization system with ten columns for controlling temperature profile. PAN precursor was spun with a different spinning rate. PAN spun fibers were stabilized with a total duration of 45 to 110 min at a given temperature profile. Furthermore, a stabilization temperature profile was varied with the last column temperature from 230 to $275^{\circ}C$. Stabilized fibers were carbonized in nitrogen atmosphere at $1200^{\circ}C$ in a furnace. Morphologies of spun and CFs were observed using optical and scanning electron microscopy, respectively. Tensile properties of resulting CFs were measured. The results revealed that process conditions such as spinning rate, stabilization time, and temperature profile affect microstructure and tensile properties of CFs significantly.

• 한국세라믹학회지
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• 제36권6호
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• pp.577-582
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• 1999

Activated carbon fibers were prepared from stabilized PAN fibers by chemical activation using hydroxide. The variations in specific surface area amount of iodine adsorption micro-structure and pore size distribution in the activated carbon fibers after the activation process were discussed. In the chemical activation using potassium hydroxide specific surface area of about 2545m2/g and amount of iodine adsorption of 2049 mg/g were obtained at the condition of KOH/fiber ratio of 1 and 800$^{\circ}C$ Nitrogen adsorption isotherms for PAN based activated carbon fibers showed the type I in the Brunauer-Deming-Deming-Teller classification indicating the micro-pores consisting the activated fibers.

• 한국염색가공학회지
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• 제15권2호
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• pp.76-85
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• 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.

• 한국세라믹학회지
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• 제34권1호
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• pp.56-62
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• 1997

탄화된 PAN 섬유, 페놀수지, 세라믹 결합체를 혼합하여 탄소섬유-세라믹복합체를 제조한 후 활성화시켜 PAN 섬유의 탄화온도에 따른 활성탄소섬유-세라믹복합체의 비표명적과 굽힘 강도변화를 연구하였다. 안정화 PAN 섬유를 80$0^{\circ}C$와 100$0^{\circ}C$에서 각각 탄화시켜 얻은 두 종류의 탄소섬유를 복합체 제작시편의 원료로 사용하였다. 탄소섬유-세라믹복합체를 10~90분간 CO2로 85$0^{\circ}C$에서 활성화시켜 얻은 두 종류의 활성복합체에 대한 물성 측정결과, 80$0^{\circ}C$로 PAN 섬유를 탄화시켜 만든 활성복합체의 burn-off이 37%에서 76%로 증가될 때 비표면적은 493m2/g에서 1090m2/g으로 증가하였으며, 굽힘강도는 4.5 MPa에서 1.4MPa로 감소하였다. 이 값들은 안정화 PAN 섬유의 탄화온도를 100$0^{\circ}C$로하여 활성복합체 시편이 나타내는 값보다 약 2배 정도 큰 값이었다. 비표면적, 굽힘강도 측정결과와 미세조직 관찰결과, PAN 섬유의 탄화온도가 활성복합체의 비표면적과 굽힘강도에 미치는 영향은 활성화시 탄소섬유와 페놀수지탄화체 또는 세라믹 필름간에 발생되는 결합력과 상대적인 수축율에 의해 결정되는 활성복합체의 구조특성에 기인된 것으로 해석하였다.

• 한국재료학회지
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• 제7권10호
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• pp.838-844
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• 1997

폴리아크릴로나트릴(PAN)계 탄소섬유 및 안정화 PAN섬유를 사용하여 제조한 페놀수지 복합재료의 열주기 산화저항성에 섬유표면의 인산코팅 유.무가 미치는 영향을 조사하였다. 각 복합재료의 열주기 산화저항성은 열중량분석기의 원리를 응용하여, 공기중에서 hot zone과 cold zone을 주기적으로 반복이동하는 열충격조건에 노출되면서 초래되는 복합재료의 중량변화를 측정하여 비교하였다. 시험변수로는 hot zone에 노출된 온도, 시간 및 싸이클횟수를 선정하였다. 이 시험방법은 비교적 단순하며, 작은 크기의 시편으로도 가능하고, 중량변화가 온-라인 모니터에서 직접 감지되므로 데이타의 신뢰성이 \ulcorner다. 각 시험조건에서 인산코팅한 섬유를 사용한 복합재료가 그렇지 않은 재료보다 고온에서의 높은 산화저항성 때문에 우수한 열주기저항성을 보여 주었다. 또한 인산코팅의 존재 여부가 열주기시험 후의 탄소섬유-페놀수지 및 안정화 PAN섬유-페놀수지 복합재료의 미세구조에 미치는 영향을 조사하였다.

• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.777-781
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• 2008

In this work, silver nanoparticles-containing polyacrylonitrile (PAN) solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of nanofibers. The inputted voltage and PAN content in the solution were fixed at 15 kV and 10 wt.% in DMF with 10 cm of tip-to-collector distance (TCD). The PAN/Ag nanofiber webs were stabilized by oxidation at 250 ${^{\circ}C}$ for 2 h in air and carbonized at 1000 ${^{\circ}C}$ for 2 h in $N_2$. The resultant diameter distribution and morphologies of the nanofibers were evaluated by scanning electron microscope analysis. The electrochemical behaviors of the nanofiber webs were also observed by cyclic voltammetry tests. It was found that the presence of silver nanoparticles in carbon nanofiber webs led to the increase of specific capacitance and the decrease of fiber diameters.

• Carbon letters
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• 제12권1호
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• pp.16-20
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• 2011

Commercial PAN fibers were thermally stabilized at 220 or $240^{\circ}C$ for 30 min. Those fibers were further stabilized using radio-frequency (RF) capacitive plasma discharge during 5 or 15 min. From Fourier transform infrared spectroscopy results, it was observed that an additional plasma treatment led to further stabilization of PAN fibers. After stabilization, carbonization was performed to investigate the final tensile properties of the fabricated carbon fibers (CFs). The results revealed that a combination of thermal and plasma treatment is a possible stabilization process for manufacturing CFs. Morphology of CFs was investigated using scanning electron microscopy. The morphology shows that the plasma stabilization performed by the RF large gap plasma discharge may damage the surface of the CF, so it is necessary to select a proper process condition to minimize the damage.