A novel electrode for an NO gas sensor was fabricated from electrospun polyacrylonitrile fibers by thermal treatment to obtain carbon fibers followed by chemical activation to enhance the activity of gas adsorption sites. The activation process improved the porous structure, increasing the specific surface area and allowing for efficient gas adsorption. The gas sensing ability and response time were improved by the increased surface area and micropore fraction. High performance gas sensing was then demonstrated by following a proposed mechanism based on the activation effects. Initially, the pore structure developed by activation significantly increased the amount of adsorbed gas, as shown by the high sensitivity of the gas sensor. Additionally, the increased micropore fraction enabled a rapid sensor response time due to improve the adsorption speed. Overall, the sensitivity for NO gas was improved approximately six-fold, and the response time was reduced by approximately 83% due to the effects of chemical activation.

Commercial PAN fibers were thermally stabilized at 220 or 240℃ 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.

Recently, the use of thermal conductive polymeric composites is growing up, where the polymers filled with the thermally conductive fillers effectively dissipate heat generated from electronic components. Therefore, the management of heat is directly related to the lifetime of electronic devices. For the purpose of the improvement of thermal conductivity of composites, fillers with excellent thermally conductive behavior are commonly used. Thermally conductive particles filled polymer composites have advantages due to their easy processibility, low cost, and durability to the corrosion. Especially, carbon-based 1-dimensional nanomaterials such as carbon nanotube (CNT) and carbon nanofiber (CNF) have gained much attention for their excellent thermal conductivity, corrosion resistance and low thermal expansion coefficient than the metals. This paper aims to review the research trends in the improvement of thermal conductivity of the carbon-based materials filled polymer composites.

Since it has been reported that asbestos fibers cause serious health problems such as lung cancer, malignant mesothelioma and other related diseases, it turns into social issue leading to a number of studies for characterizing asbestos found in the indoor environment. Among the established methods for detecting asbestos fibers, phase contrast microscopy (PCM) method is widely used as it dose not require complicated process nor high-priced equipments. However, PCM method is hard to define a sort of asbestos and to detect tiny asbestos fibers. We developed an image-based high-throughput microscopy (HTM) for automated counting of asbestos fibers which were distinguishable from the spherical particles. HTM method enabled us to analyze asbestos fibers both automatically and quantitatively. Test samples of chrysotile, amosite and crocidolite, which are frequently detected in Korea, were used in this study and comparisons were made between concentrations of asbestos fibers measured by manual counting method and HTM method. Application of HTM system can be extended to various areas such as malaria diagnosis, rare cell detection and bacterial colony counting.

이 연구에서는 녹차를 이용한 친환경 복합보드를 건축내장재로의 활용을 위하여, 녹차의 다양한 기능성과 목재섬유의 우수한 강도특성을 살려 녹차-목재섬유 복합보드를 제작하였고, 녹차-목재섬유 복합보드의 정 적 휨강도성능에 미치는 녹차와 목재섬유 배합비율 및 접착제의 영향을 조사하였다. 녹차-목재섬유복합보드 의 휨 강도성능은 녹차의 배합에 따라 대조보드 (control 보드) 보드의 그것보다 감소하였는데, 그 감소비율 은 전반적으로 녹차배합비율이 증가할수록 커지는 경향을 나타내었다. 또한, 보드제조에 사용된 수지의 종 류에 따라 강도성능의 차이가 나타났는데, 포름알데히드 방산량이 많은 E1급 요소수지가 E0급 요소수지보 다 휨 탄성계수에서는 1.08∼1.53배 그리고 휨 강도는 1.19∼1.82배의 더 높은 값을 나타내었으며, 녹차의 배합비율이 커질수록 양자의 차이는 커지는 것이 확인되었다. 휨 강도는 E1급 요소수지의 경우, 시판용 중밀 도섬유판 (medium density fiberboard, MDF)의 0.94∼1.03배의 값을 나타내어 시판용 중밀도섬유판과 거 의 차이가 없었고, 녹차와 목재섬유를 복합한 우수한 친환경 기능성복합보드제조가 가능한 것이 밝혀졌다.

PAN precursor fibers were produced via wet-spinning process, and effects of polymerization and spinning processes, especially the stretching process, were investigated on mechanical properties and micro-morphologies of precursor fibers. An increase in molecular weight, dope solid and densification and a decrease in surface defects were possible by controlling polymerization temperature, the number of heating rollers for densification and the jet stretch ratio, which improved the mechanical properties of precursor fibers. The curves for strength, modulus, tensile power and diameter as a function of stretch ratio can be divided into three stages: steady change area, little change area and sudden change area. With the increase of stretch ratio, the fiber diameter became smaller, the degree of crystallization increased and the structure of precursor fibers became compact and homogeneous, which resulted in the increase of strength, modulus and tensile power of precursor fibers. Empirical relationship between fiber strength and stretch ratio was studied by using the sub-cluster statistical theory. It was successfully predicted when the strengths were 0.8 GPa and 1.0 GPa under a certain technical condition, the corresponding stretch ratio of the fiber were 11.16 and 12.83 respectively.

Electrospinning is a technique that produces sub-micron sized continuous fibers by electric force from polymer solutions or melts. Due to its versatile manufacturability and the cost effectiveness, this method has been recently adopted for the fabrication of one-dimensional materials. Here, we fabricated polyacrylonitrile (PAN) polymer fibers, from which uniform carbon fibers with diameters of 100-200 nm were obtained after carbonization at 800 ˚C in N2. Special emphasis was directed to the influence of the phase separated polymer solution on the morphology and the microstructure of the resulting carbon fiber. The addition of poly(stylene-co-acrylonitile) (SAN) makes the polymer solution phase separated, which allows for the formation of internal pores by its selective elimination after electrospinning. XPS and Raman Spectroscopy were used to confirm the surface composition and the degree of carbonization. At the PAN:SAN = 50:50 in vol%, the uniform carbon fibers with diameters of 300~500 nm and surface area of 131.6 m2g-1 were obtained.

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.

광섬유의 클래딩 부분을 별도의 고정구에 직접 부착하는 방식으로 고정하여, 변형발생 시 광케이블을 구성하는 재료들 사이에서 발생하는 미끄러짐(Slip)현상을 방지하고, 외력에 의해 발생하는 변형을 정확하게 측정이 가능하도록 함과 기존 광섬유격자센서가 자체적으로 압축변형의 측정이 곤란한 점을 개선하기 위해 미리 긴장(Pre-Strain)상태를 유지하기 위하여 두 개의 접점사이를 볼트와 너트로 조절하여 프리스트레인 가변이 가능하도록 하여 인장/압축변형 측정을 가능하게 한 광섬유격자센서 패키지를 사용하는 지하구조물 변위 모니터링시스템이 본 연구에 의해 개발되었다. 이러한 광섬유격자센서 패키지는 콘크리트 라이닝구조물에 콘크리트의 불균일성을 극복하고 대표성을 가지기 위해 1미터 게이지 길이를 갖도록 하여 모니터링시스템에 적용되었으며, 대구 지하철 지하구조물에 현재 운영 중인 이 시스템은 한국전력 공동구 설치공사가 진행되면서 구조물에 미치는 영향을 판단하기 위한 모니터링시스템으로 적용되었다.

The principal aims of the review paper are (1) to establish broad overview information, both qualitative and quantitative, relating to the world market for polyacrylonitrile (PAN) or pitch-based carbon fibers; and (2) to generate an effective analysis and break down of consumption by process route and eventual end-use. The review paper also designed specifically to provide subscribers with an accurate, independent, and realistic assessment of the current status and future perspective of the market for carbon fibers in the world. The world market for carbon fibers continues to grow rapidly, fuelled by new industrial end uses, such as sport and leisure goods, aerospace, automotive applications, civil engineering and infrastructure repair, and immerging applications in energy generation. Demands for properties of carbon fibers used in those applications include many things such as strength, toughness, fatigue property, corrosion resistance, heat resistance, etc., and these become to be higher level. On the other hand, demands for manufacturing technologies of carbon fibers become to be difficult with these demands for properties, and these are wide variety such as high efficiencies, high qualities, many functions, labor saving, and low cost. In this review paper, thus, the recent carbon fibers corresponded to these needs, and its latest manufacturing technologies as well as market prospects are described.

Carbon fibers are a new breed of high-strength materials which have been described as a fiber containing at least 90% carbon obtained by the controlled pyrolysis of appropriate fibers. Carbon fiber composites are ideally suited to applications where strength, stiffness, lower weight, and outstanding fatigue characteristics are critical requirements. They also can be used in the occasion where high temperature, chemical inertness and high damping are important. In recent decades, carbon fibers have found wide applications in commercial and civilian aircraft, recreational, industrial, and transportation markets. Therefore, understanding the basic structure, synthesis and physicochemical properties of carbon fibers is very important to apply them as a precursor of above applications. This review paper discuss the general information and manufacture technique of carbon fibers used for improving the performance of composite materials in various industries for the present.

In order to improve the thermal stability of PAN-based electrospun fibers, AP-PER-MEL and TiO2 were added in to the fibers as additives. The polymer composite with uniformly mixed additional agents was obtained. In case of non-treated sample, the fibers were burn off completely with high rate within 620℃. But in case of treated samples (EF-M and EF-MT), it is sure that the thermal stability was improved by studying TGA data and ISO flammability test about 20 and 30%, respectively. A synergy effect of adding two kinds of agents (AP-PER-MEL and TiO2) into PAN-based electrospun fibers was confirmed. Through SEM images, it is confirmed that the fiber shape can be kept even after addition of agents (AP-PER-MEL and TiO2). Finally the thermal stability of fibers was largely developed with keeping the nature of PAN-based fibers effectively.

High modulus pitch based carbon fibers (HM) were exposed to isothermal oxidation using tube furnace in carbon dioxide gas to study the oxidation kinetics under the temperature of 800-1100℃. The kinetic equation f=1--(-atb) was introduced and the constant b was obtained in the range of 1.02~1.42. The oxidation kinetics were evaluated by the reaction-controlling regime (RCR) depending upon the apparent activation energies with the conversion increasing from 0.2 to 0.8. The activation energies decrease from 24.7 to 21.0 kcal/mole with the conversion increasing from 0.2 to 0.8, respectively. According to the RCR, the reaction was limited by more diffusion controlling regime for the HM fibers with the conversion increasing. Therefore, it seems that the oxidation which is under the diffusion controlling regime takes place continuously from the skin to the core of the fiber.

In this work, we employed an electroless nickel plating on glass fibers in order to enhance the electric conductivity of fibers. And the effects of metal content and plating time on the conductivity of fibers were investigated. From the results, island-like metal clusters were found on the fiber surfaces in initial plating state, and perfect metallic layers were observed after 10 min of plating time. The thickness of metallic layers on fiber surfaces was proportion to plating time, and the electric conductivity showed similar trends. The nickel cluster sizes on fibers decreased with increasing plating time, indicating that surface energetics of the fibers could become more homogeneous and make well-packed metallic layers, resulting in the high conductivity of Ni/glass fibers.

Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.

In this study, commercially available pitch-based carbon fibers of general grade were post-heat-treated using a boxtype high temperature furnace at 1800℃, 2000˚, 2200℃, and 2400℃, respectively. The fundamental characteristics of each heat-treated carbon fibers were investigated in terms of chemical composition, morphology, thermal stability, X-ray diffraction, single filament tensile test, and electrical resistivity. The result showed that the fiber properties were significantly influenced by the post-heat-treatment, indicating the greater effect with increasing treatment temperature. The carbon contents, thermal stability, and tensile properties of the carbon fibers used here were further increased by the post-heat-treatment, whereas the d-spacing between graphene layers and the electrical resistivity were reduced with increasing post-heat-treatment temperature.

Oxidized PAN (OXI-PAN) fibers were used for the precursors of activated carbon fiber in study. How drying temperature affected the properties of carbon fibers on activating process of carbon fibers was investigated. The specific surface areas of activated carbon fibers have been determined on a series of chemically activated carbons with KOH and NaOH. The experimental data showed variations in specific surface area, iodine and silver adsorptions by the activated carbon fibers. The amount of iodine adsorption increases with increasing specific surface areas in both activation methods. This was because the ionic radius of iodine was smaller than the interior micropore size of activated carbon fibers. Silver adsorbed well in NaOH activated carbon fibers rather than KOH activated carbon fibers in this study.