• 펄프종이기술
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• 제45권1호
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• pp.59-66
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• 2013

Fillers have been used for printing paper to improve printability, sheet formation and optical properties and to reduce production costs by replacing expensive wood pulps. However, an increased filler content will decrease paper strength because filler particles interfere with fiber-fiber bonding. In order to increase filler content without sacrificing too much paper strength in high filler content papers, the surface of precipitated calcium carbonate (PCC) has been modified by adsorbing anionic polyacrylamide and cationic starch in series. The adsorbed polymer layers would enhance interactions between the filler surface and the fiber surface, improving internal bonding. It was found that the modified PCC increased paper strength at a given filler content compared to the coventional method. Negligible differences in optical properties and formation of paper, filler and fines retention and drainage on the wire section were observed between the modified and the conventional PCC. However, the decreased bulk of paper was observed when the modified PCC was used.

• 한국가구학회지
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• 제19권2호
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• pp.111-115
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• 2008

An experiment was conducted to know ultra-pure distilled water penetration depth through large vessel, small vessel, latewood fiber and earlywood fiber in longitudinal direction of Castanea crenata. In heartwood, latewood fiber transported water more than large and small vessel. While in sapwood, small vessel conduction depth was found the highest. Penetration depth of water after 15.0 seconds, no significant difference was observed among earlywood fiber, latewood fiber and earlywood vessel. Whilst in heartwood, no statistical difference was observed among earlywood fiber, latewood fiber and earlywood vessel. At the beginning, the speed of water penetration was high and then gradually decreased.

• Composites Research
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• 제30권6호
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• pp.365-370
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• 2017

탄소섬유 강화 열가소성 수지 복합재료(Carbon fiber reinforced thermoplastic composites; CFRTPs)의 물성은 다양한 요인들에 영향을 받는다. 그 중에서도 탄소섬유 표면에 Sizing되어 있는 에폭시(Epoxy) 층은 열가소성 수지와 상호 작용(Interaction)이 없어 매우 취약한 계면을 형성하며, 열가소성 수지의 높은 용융 점도(Melting viscosity)는 탄소섬유 다발(Bundle) 사이로 함침(Impregnation)이 어려워 탄소섬유 강화 복합재료 내부에 기공(Void)를 형성한다. 이와 같이 탄소섬유와 열가소성 수지 간의 낮은 계면전단강도(Interfacial shear strength)은 탄소섬유강화 열가소성 복합재료(Carbon fiber reinforced thermoplastic composites; CFRTPs)의 기계적 물성을 저하시키는 가장 중요한 요인 중 하나이다. 따라서, 본 연구에서는 열가소성 수지와의 상호작용이 없는 탄소섬유 표면의 에폭시 층을 열풍을 통해 제거하고, 열가소성 수지의 점도를 낮춰 함침도를 향상시키기 위해서 용액형 열가소성 수지를 제조하여 탄소섬유 표면에 Sizing 처리 함으로써 CFRTPs의 물성을 향상시켰다. CFRTPs의 층간전단강도(Interlaminar shear strength; ILSS) 및 굽힘 강도(Flexural strength)를 통해 이를 검증하였으며, 수지의 함침도는 기공률(Void content)의 계산을 통해 분석하였다.

• Carbon letters
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• 제15권3호
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• pp.162-170
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• 2014

Pitch is an attractive raw material for carbon fiber precursors due to its low cost stemming from its availability as a residue of coking and petroleum processes. Ford Motor Company reported a carbon fiber target price of $11.0/kg by using a fast cycle-time manufacturing method with carbon fiber in an inexpensive format, allowing for an average retail price of gasoline of $3.58/gallon. They also recommended the use of carbon fiber with strength of 1700 MPa, modulus of 170 GPa, and 1.5% elongation. This study introduced a ca. $5.5{\mu}m$ carbon fiber with 2000 MPa tensile strength obtained from a precursor through simple distillation of petroleum residue. Petroleum pitch based carbon nanofibers prepared via electrospinning were characterized and potential applications were introduced on the basis of their large specific surface area and relatively high electrical conductivity.

• 한국염색가공학회지
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• 제19권2호
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• pp.44-49
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• 2007

Antimicrobial fibers were prepared by an electro-spinning method. Polystyrene hydantoin(PSH) was employed as an antimicrobial precursor to produce an electro-spun antimicrobial acrylic fiber. Increasing the surface area of hydrophobic antimicrobial-fibers provides enhanced antimicrobial efficacy. The biocidal activity of electro-spun acrylic fibers could be rendered through chlorine bleach treatment, and the antimicrobial effectiveness against gram-Positive and gram-negative bacteria was investigated. In addition, scanning electron microscopy(SEM) demonstrated the feature of the electro-spun fibers.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.271-278
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• 2006

We used polymers of alternating cationic and anionic nature to build up shells on fiber surfaces, strengthen the worn-out fibers and improve paper properties made from such fibers. OCC and ONP pulps were either dipped or salted out in the cationic polyallylamine, polyacrylamide and starch solutions. After centrifugal drying, these were followed by treatments in anionic polyacrylic acid, poly-acrylamide, and starch solutions, respectively. The shell-enhanced fibers were formed into handsheets and their physical properties evaluated. The results show that building multiple shells on worn-out fiber surfaces can strengthen the fibers and paper. The simpler and more practical impregnation-centrifuging treatment provided the desired effects, whereas salting out the polymers produced somewhat superior fibers. The latter process, were impractical, however. The first pair of polymeric shells imparted marked strength improvement, whereas later layers had diminishing efficacies. Overall, the methods can improve fiber quality, attaining paper strength requirements without resorting to expensive measures. Alternate cationic polymer and filler powders were also deposited on fiber surface based on the micriparticle system in an anticipation of stiffness gains. Platy minerals, such as montmorillonite, bentonite, sericite, clay and talc were added following cationic PAM. After dewatering of polymer-pigment shelled fiber of one to 3 pairs of layers, handsheets either calendered or uncalendered were evaluated. The results indicate that regardless of calendaring, stiffness of the handsheets did not improve appreciably while certain other strength properties showed gains. We also attempted the novel starch gel filler addition method wherein tapioca starch and filers (PCC, sericite or clay) were mixed at high solids content of 50% and cooked until gelatinized. The filled handsheets were dried under various conditions and then tested for their properties. Improvements in strengths of modified filled paper were observed.

• Structural Monitoring and Maintenance
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• 제10권4호
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• pp.299-314
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• 2023

Long-gauge carbon fiber line (CFL) sensors have received considerable attention in the past decade. However, there is still a need for an in-depth investigation of their measuring accuracy. This study investigates the accuracy of carbon fiber line sensors to monitor and differentiate the flexural behavior of two beams, one reinforced with steel bars alone and the other reinforced with steel and basalt fiber-reinforced polymer bars. A distributed set of long-gauge carbon fiber line, Fiber Bragg Grating (FBG), and traditional strain gauge sensors was mounted on the tensile concrete surface of the studied beams to compare the results and assess the accuracies of the proposed sensors. The test beams were loaded monotonically under four-point bending loading until failure. Results indicated the importance of using long-gauge sensors in providing useful, accurate, and reliable information regarding global structural behavior, while point sensors are affected by local damage and strain concentrations. Furthermore, long-gauge carbon fiber line sensors demonstrated good agreement with the corresponding Fiber Bragg Grating sensors with acceptable accuracy, thereby exhibiting potential for application in monitoring the health of large-scale structures.

• 공업화학
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• 제19권5호
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• pp.484-490
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• 2008

폴리비닐피로디온을 서로 다른 끓는점, 유전상수, 쌍극자모멘트를 갖는 다양한 용매(메탄올, 에탄올, 2-프로판올, 부탄올, 아세톤, 메틸렌클로라이드 및 DMF)에 용해시켜 전기방사를 시도하여 섬유의 특성을 연구하였다. 전기 방사된 폴리비닐피로디온은 방사용액의 점도, 전기전도도 및 표면장력에 영향을 받는다. 점도가 $0.114kg/m{\cdot}s$ 이상, 전기전도도는 1.02 mS/m 이상, 표면장력은 30.0 mN/m 이하에서 섬유가 형성되었다. 에탄올 용매계에서 폴리비닐피로디온의 평균직경은 인가전압이 10 kV에서 20 kV 증가시킴에 따라 1710에서 5454 nm까지 증가하였다.

• 대한공업교육학회지
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• 제34권2호
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• pp.346-362
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• 2009

본 연구는 광섬유센서를 이용하여 표면조도의 간이 비접촉 측정기를 개발하는데 목적이 있다. 광섬유 센서의 장점은 우수한 고속 응답성, 자기의 무영향, 제작의 편이성이다. 광섬유센서 표면조도 측정 원리는 측정물의 표면조도에 따라 반사되는 광의 세기와 기지의 표면조도 값을 일대일 대응시키는 것이다. 반사광의 세기는 센서 프로브로부터 표면까지의 거리와 표면조도에 따른 반사한계각에 따라 결정되는데 본 연구에서는 표면까지의 거리를 일정하게 하여 표면조도에 따른 반사한계각만을 가지고 표면조도가 결정되도록 측정 프로브를 제작하였다. 측정 시스템은 발광부, 수광부과 신호처리부로 구성되었다. 이 실험에서 사용된 표준 측정 재료는 SM45C, STS303과 Al60이었다. 연구결과 첫째, 재료에 따른 표면조도와 센서출력의 상관관계로부터 근사표면조도식을 도출하고 임의 가공된 시료의 표면조도 측정을 통해 근사표면조도식이 유효함을 입증하였다. 둘째, 실제 제작한 간이 광섬유센서 표면조도 측정기가 유용함을 입증하였다.

• 한국안전학회지
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• 제31권1호
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• pp.66-73
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• 2016

Lyocell fibers were used as a precursor in order to improve yield and strength of cellulose-based precursor while manufacturing activated carbon fiber(ACF). Lyocell fibers as a precursor for the preparation of ACF were surface-modified by reaction with 3-aminopropyltriethoxysilane(APTES) and pre-treated with KOH and H3PO4. Using aforementioned precursor, ACFs were prepared by a series of stabilization, carbonization and activation process at high temperatures. On each process, FT-IR, TGA, UTM and SEM were used to observe fibers' physical properties including structure and porous surfaces. FT-IR results proved that surface modification was achieved during stabilization, carbonization and activation process. TGA results during carbonization process found that surface modified fibers with APTES 0.02 mol(A2) showed higher thermostability, and extended pre-treatment increased yield. Especially, yield was found to have an increase of 10~20 wt% with surface modification during activation process. UTM results showed that tensile strength has the same order of concentration of APTES after surface modification, however, was found to show lower tensile strength than lyocell fibers after stabilization process. SEM results revealed that more homogeneous porosity control could be proceed after modifying the surface for the effective removal of hazardous substances.