This study provides an economical and effective method to improve the interlaminar properties of carbon fiber-reinforced polymers (CFRPs) using aluminum trihydroxide (ATH) microparticles. ATH microparticles are cheap and are expected to show good affinity to epoxies in the matrix and sizing agents of the carbon fibers owing to the presence of three hydroxyl groups. In addition, ATH particles are reported to improve the mechanical properties of polymers when used as the reinforcement. In this study, ATH microparticles of various sizes, 1.5, 10, and 20 μm, were used to improve the interlaminar properties of the CFRPs. ATH particles with a size of 1.5 μm improved the tensile properties of the ATH/epoxy resin and did not significantly alter the curing behavior. The interfacial adhesion between the carbon fiber and the epoxy resin was also improved, and the impregnation of the resin mixture remained similar to that of the neat resin, resulting in no significant void and defect formation. Considering the above results, the resulting 1.5 μm ATH-reinforced CFRP showed improved interlaminar properties compared to CFRP without ATH. However, 10 and 20 μm ATH-reinforced CFRPs showed deteriorated interlaminar properties due to the diminished tensile properties of the resin itself and resin impregnation, which resulted in more voids and defects, despite the interfacial adhesion between the fiber and the matrix resin.

Carbon molecular sieve (CMS) membrane surpasses the upper-bound trade-off and plasticization phenomenon of polymer membrane. Recently, supported CMS membranes have been investigated to provide both high performance and mechanical strength. Herein, we have investigated the supported CMS hollow fiber membranes on low-cost alumina hollow fiber. To prepare the thin and uniform layers, the dip-coating parameters for intermediate and polymeric layers were varied in terms of the withdrawal rate and solution viscosity, respectively. Then, in order to confirm its feasibility in real industry, mixture gas was permeated through prepared CMS membranes. Moreover, the property of long-term stability was characterized in harsh conditions and further modified.

천연가스, 산업공정, 화석연료의 연소과정과 같은 대규모 고정 배출원에서 발생하는 온실가스인 CO2를 포집하기 위한 기술 개발이 전 세계적으로 활발하게 수행되고 있다. 특히, 습식 흡수 법은 비교적 낮은 CO2분압에서도 높은 제거 효율을 달성할 수 있어 많은 개발이 이루어져온 포집 기술이다. 하지만 흡수제의 재생에 필요한 에너지가 과다한 문제가 있으며, 충분한 부지가 확보되어야하기 때문에 공정 상용화에는 큰 걸림돌이 있다. 이러한 문제를 극복하고 공정 효율을 개선 할 수 있는 접촉분리막 공정 기술이 최근 주목받고 있다. 본 연구에서는 접촉분리막과 화학적 습식 아민 흡수제를 이용한 이산화탄소 제거 특성을 분석하였다.

탄소섬유는 인장강도와 내구성이 우수하므로 구조물의 표면에 탄소섬유시트를 부착하는 보강공법은 콘크리트 구조물의 보수 및 보강에 사용되는 대표적인 방법이다. 그러나 탄소섬유시트 부착공법은 시공 후 보강성능의 확인이 어려운 단점이 있다. 탄소섬유시트에 광섬유를 매입하여 계측이 가능한 보강재로 사용하는 경우 미부착이나 탈락된 부위를 찾아내어 구조물의 보강수준을 평가할 수 있을 것으로 기대된다. 본 연구는 제작된 센싱보강재의 기본적인 가능성을 확인하기 위해 센싱보강재의 크기와 매립된 광섬유의 간격을 변인으로 두고 센싱보강재 실험체를 제작하였다. BOTDR (Brillouin Optical Time Domain Reflectometer)을 사용하여 시편의 변형에 따른 광섬유의 산란광으로부터 변형률을 계측하고 응답을 분석하였다. 분석 결과로부터 보강수준 정량화를 위한 센싱보강재의 적용성 및 BOTDR의 최소요구성능을 확인하였다.

The purpose of this study was to develop a carbon fiber sheet with embedded fiber optic sensor for maintenance and performance improvement of aged concrete bridges. The carbon fiber sheet reinforcement method can separate the concrete and the carbon fiber sheet, so it is necessary to investigate the bond performance level. However, separation of concrete and carbon fiber sheet and investigation of concrete scaling phenomenon are carried out by human, so it is difficult to secure objectivity and accurate investigation. Therefore, in this study, a method to confirm the bond level of carbon fiber sheet by reinforcing with a carbon fiber sheet with a fiber optic sensor was examined. In this study, we investigated the strain of fiber optic sensor embedded in carbon fiber sheet to identify the separate point of carbon fiber sheet. The strain measured by fiber optic sensor was measured by numerical analysis. The strain rate of the carbon fiber sheet was compared with that of the carbon fiber sheet. As a result, it was confirmed that the strain was changed at the point where the carbon fiber sheet was separated, and the strain occurred in the carbon fiber sheet was examined to predict the separate point.

본 연구에서는 시판되는 탄소전극의 제조에 활용되는 활성탄의 형태가 아닌, 활성탄소섬유를 이용하여 축전식 탈염공정에 적용할 탄소전극을 제조하였다. polyvinylidene fluoride (PVDF)를 지지체로 사용하며 활성탄소섬유를 배합한 후 시판되는 그라파이트 시트에 캐스팅하여 탄소전극을 제조한 다음 염 제거 효율을 평가하였다. 활성탄소섬유의 입자 크기를 달리하였고 용매와 고분자 지지체 그리고 활성탄소섬유를 80 : 2 : 18, 80 : 5 : 15의 배합비율로 전극을 제조하였다. 축전식 탈염공정 운전조건으로 흡착전압, 시간, 탈착전압, 시간, NaCl 공급액의 농도와 유속 등을 달리하여 제조한 활성탄소섬유전극의 성능을 평가하였다.

To separate olefin from paraffin efficiently, highly selective and permeable carbon molecular sieve (CMS) membrane has been employed. Especially, supported CMS membrane could offer high permeance and mechanical strength. However, it has been limited to flat or tubular type membranes despite a lower packing density due to a difficult manufacturing process of hollow fiber membrane. Thus, we have optimized the process to prepare the CMS membrane on alumina hollow fiber. To coat a defect-free thin alumina intermediate layer, the withdrawal speed during dip-coating process was varied, and the viscosity of polymer solution was controlled to form uniform layer. Then, the pyrolyzed CMS membrane was tested in propylene/propane mixture gas system as well as single component. Moreover, a long-term performance was evaluated in harsh conditions.

The South Korean Ministry of the Environment has revised the laws relating to the management of interior air quality for multiple use facilities, and recommends maintaining carbon dioxide (CO2) concentration in passenger vehicles below 1000 ppm during operation in urban areas of large cities. However, the interior CO2 concentration of passenger vehicles can rapidly increase and exceed 5000 ppm within 30 min, as observed when two passengers are traveling in urban areas of the South Korean city of Jeonju with the air conditioner blower turned off and the actuator mode set to internal circulation mode. With four passengers, CO2 concentration can reach up to 6000 ppm within 10 min. To counter this, when the actuator is set to external mode, CO2 concentration can be maintained below 1000 ppm, even after a long period of running time. As part of the air conditioning system, alkali-treated activated carbon fiber filters are considered to be far superior to the commercial non-woven filters or combination filters currently commonly in use.

Pollution of chloride ion-reinforced concrete can trigger active corrosion processes that reduce the useful life of structures. Multifunctional materials used as a counter-electrode by electrochemical techniques have been used to rehabilitate contaminated concrete. Cement-based pastes added to carbonaceous material, fibers or dust, have been used as an anode in the non-destructive Electrochemical Chloride Extraction (ECE) technique. We studied the performance of the addition of Carbon Fiber (CF) in a cement-graphite powder base paste used as an anode in ECE of concretes contaminated with chlorides from the preparation of the mixture. The experimental parameters were: 2.3% of free chlorides, 21 days of ECE application, a Carbon Fiber Volume Fraction (CFVF) of 0.1, 0.3, 0.6, 0.9%, a lithium borate alkaline electrolyte, a current density of 4.0 A / m2 and a cement/graphite ratio of 1.0 for the paste. The efficiency of the ECE in the traditional technique using metal mesh as an anode was 77.6% and for CFVF of 0.9% it was 90.4%, with a tendency to increase to higher percentages of the CFVF in the conductive cement-graphite paste, keeping the pH stable and achieving a homogeneous ECE in the mass of the concrete contaminated with chlorides.

Milled carbon fiber (mCF) was prepared by a ball milling process, and X-ray diffraction (XRD) diffractograms were obtained by a 2θ continuous scanning analysis to study mCF crystallinity as a function of milling time. The raw material for the mCF was polyacrylonitrile- based carbon fiber (T700). As the milling time increased, the mean particle size of the mCF consistently decreased, reaching 1.826 μm at a milling time of 18 h. The XRD analysis showed that, as the milling time increased, the fraction of the crystalline carbon decreased, while the fraction of the amorphous carbon increased. The (002) peak became asymmetric before and after milling as the left side of the peak showed an increasingly gentle slope. For analysis, the asymmetric (002) peak was deconvoluted into two peaks, less-developed crystalline carbon (LDCC) and more-developed crystalline carbon. In both peaks, Lc decreased and d002 increased, but no significant change was observed after 6 h of milling time. In addition, the fraction of LDCC increased. As the milling continued, the mCF became more amorphous, possibly due to damage to the crystal lattices by the milling.

The purpose of this study is to develop a carbon fiber sheet with embedded fiber optic sensor for maintenance and performance improvement of aged concrete bridges. The carbon fiber sheet bonded method has many advantages in terms of member repair and reinforcement, but it is disadvantageous in that it is necessary to directly identify the separate point generated during the bonded of the carbon fiber sheets by an artificial method. In this study, we examined the method of confirming the separate point of the carbon fiber sheets by examining the strain of the fiber optic sensor embedded in the carbon fiber sheets. The strain rate measured by the fiber optic sensor was replaced by the strain of the carbon fiber sheets derived from the FEM analysis.

In this study, we tried to prepare an isotropic spinnable pitch which can be useful to prepare the general purpose carbon fiber through the co-carbonization of biomass tar with ethylene bottom oil under two different preparation methods (atmospheric distillation, pressurized distillation). The results showed that the ethylene bottom oil added co-carbonization was very effective to decrease of the oxygen contents for obtaining a stable spinnable pitch. The pressurized distillation was more effective to reduce the oxygen functional groups of pitches than atmospheric distillation. The obtained spinnable pitch by the pressurized distillation showed higher pitch yield of 42% and lower oxygen content of 9.12% than the spinnable pitch by the atmospheric distillation. The carbon fiber derived from the pressurized distillation spinnable pitch by carbonization at 800ºC for 5 min showed that the higher tensile strength of carbon fiber was increased up to 800 MPa.