부직포식 복합재(Nonwoven Web Composites)의 접착성능에 관한 전자현미경적 연구

윤형운,엄영근,김현중 國民大學校 山林科學硏究所 1999 山林科學 Vol.11 No.-

This study was carried out to investigate the effects of process variable and coupling agent(MAPP) on the adhesion characteristics of nonwoven web composites through scanning electron microscopy. Under the process conditions of 195℃ and 30㎏f/㎠ in hot-pressing temperature and pressure. 50% wood fiber and 50% polypropylene fiber on the basis of oven-dried weight, and target density of 0.7 g/㎤, the proper hot-pressing time appeared 3 minutes or longer because the polypropylene fibers in the core of composites were incompletely melted under 3 minutes. There was no significant difference in the melting extent of polypropylene fibers in the range of hot-pressing temperatures from 190℃ to 200℃. This might be attributed to the large amount and high melt flow index(MFI) of polypropylene fibers. As the addition level of polypropylene fibers to wood fibers or the melt flow index of polypropylene fibers increased, the application of relatively lower hot-pressing temperature and easier adjustment of composite thickness might be feasible in manufacturing composites. The excessively high hot-platen temperature, however, might produce the composites with decreased thickness or thickness variation because of rapid melting and flow of polypropylene fibers and might involve the risk of thermal degradation of wood fibers. Scanning electron microscopy revealed no effect of cooling time, in the range of 2 to 4 minutes, on adhesion characteristics in the composite made with 50% polypropylene fiber and 50% wood fiber. This might be attributed to the decreased internal stress which caused by the lower density level of 0.7 g/㎤ and complete melting of polypropylene fibers which added in the large amount of 50% on the basis of oven-dried weight. In the composites made with 10% polypropylene fiber and 90% wood fiber, the addition of coupling agent appeared to render the wood fibers more flexible and the adhesion between wood and polypropylene fibers better but the increased addition of coupling agent from 1 to 3% exerted little influence upon the adhesion characteristics. The addition of coupling agent, on the other hand, proved to have no effect on adhesion characteristics in the composites made with 50% polypropylene fiber and 50% wood fiber.

Electrochemical performance of a coaxial fiber-shaped asymmetric supercapacitor based on nanostructured MnO₂/CNT-web paper and Fe₂O₃/carbon fiber electrodes

Patil, Bebi,Ahn, Suhyun,Yu, Seongil,Song, Hyeonjun,Jeong, Youngjin,Kim, Ju Hwan,Ahn, Heejoon Elsevier 2018 Carbon Vol.134 No.-

<P><B>Abstract</B></P> <P>The fiber-shaped supercapacitor is a promising energy storage device in wearable and portable electronics because of its high flexibility, small size, and light weight. However, most of the reported fiber-shaped supercapacitors have exhibited low capacitance and energy density due to the limited surface area between the two fiber electrodes and operating voltage range. Herein, we successfully developed a coaxial fiber-shaped asymmetric supercapacitor (CFASC) made from MnO<SUB>2</SUB>/CNT-web paper as a cathode coupled with Fe<SUB>2</SUB>O<SUB>3</SUB>/carbon fiber as an anode with a high operating voltage of 2.2 V. The prepared CFASC device showed a high volumetric energy density of 0.43 mWh cm<SUP>−3</SUP> at a power density of 0.02 W cm<SUP>−3</SUP>, which is comparable to those of previously reported fiber-shaped supercapacitors. Additionally, CFASC exhibited good rate capability, long cycle life, and high volumetric capacitance (0.67 F cm<SUP>−3</SUP>) with excellent flexibility. The promising performance of CFASC illustrated its potential for portable and wearable energy storage devices.</P> <P><B>Graphical abstract</B></P> <P>The coaxial fiber-shaped asymmetric supercapacitor (CFASC) was successfully developed by simply wrapping the Fe<SUB>2</SUB>O<SUB>3</SUB>/CFs negative electrode with the PVA-LiClO<SUB>4</SUB> gel electrolyte-coated MnO<SUB>2</SUB>/CNT-web paper positive electrode. This CFASC can be operated at large potential windows up to 2.2 V, resulting in high specific energy, and showed excellent cycling stability and device flexibility.</P> <P>[DISPLAY OMISSION]</P>

전기방사에 의한 Polyvinylidene fluoride-hexafluoropropylene (PVDE-HFP) 극세 섬유 웹의 제조와 필터 특성

조장익,김찬,박상희,양갑승,Jo, Jang-Ik,Kim, Chan,Park, Sang-Hee,Yang, Kap-Seung 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.4

Polyvinylidene fluoride-hexafluoropropylene (PVDF- HFP)/acetone solutions were electrostatically spun into sub-micron fibers at various conditions. The variables chosen were polymer concentration, applied voltage, flow rate, and tip to collector distance (TCD). The average fiber diameter increased with an increase in the polymer concentration, however, the trend for applied voltage was not monotonous showing minimum diameter of 0.8 ${\mu}{\textrm}{m}$ at 15.6 kV. The fiber diameter was also depended on TCD; the minimum fiber diameter at 15cm. The flow rate of the solution was another factor; lower the flow rate, finer the fiber diameter. The PVDF-HFP web was also treated for air filter application i.e., water contact angle and air permeability. Though the web was consiting of ultra-fine fibers, the contact angle with water was still high as 157$^{\circ}$ representing high hydrophobicity. The web showed high air permeability of 12.69 cc/$\textrm{cm}^2$. sec, and the value decreased with increase in thickness of the web.

기하학적 영상 처리를 이용한 나노 섬유 웹의 기공 분포 측정

김주용,이정해,임대영,변성원,Kim Jooyong,Lee Jung Hae,Lim Dae Young,Byun Sung Won 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.6

An image processing algorithm has been developed in order to anlyze the nanofiber web images from a high magnification microscope. It has been known that precise pore detection of thick webs is extremely difficult mainly due to lack of light uniformity, difficulty of fine focusing and translucency of nanofiber web. The serial morphological image processing techniques of edge detection, dilation, opening, skeletonization and dilation have been applied to images for accurate pore detection followed by connect-component labeling for computing mean pore size and standard deviation of pore sizes. The pore detection algorithm developed has been found to show excellent performance in characterizing the porous structure, thus being a promising tool for the on-line quality control of eletrospun fiber manufacturing.

Electrochemical activities of Pt-Ru-Co and Pt-Ru-Ni electrocatalysts supported by a carbon fiber web

( Alfredmadzamuse ),( Louishamenu ),( Latifatumohammed ),( Sang Hern Kim ),( Yong Min Lee ),( Kwang Man Kim ),( Jang Myoun Ko ) 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Dynamic cyclic voltammetry is performed as functions of cycle number and potential window for the electrodeposition of Pt-Ru-Co and Pt-Ru-Ni catalysts on a carbon fiber (CF) web. Surface morphologies of the electrodeposited catalysts are observed by a scanning electron microscope. The electrochemical activity in methanol oxidation is examined by the cyclic voltammetry using a mixed aqueous solution of methanol as an electrolyte component. As the cycle number increases, both the current density and the amount of the electrodeposited metallic particles on the CF web are increased. The Pt-Ru-Ni/CF catalyst prepared in the potential range of -0.6 to 0.2 V and from the 1:2:2 mixed solution of H₂PtCl₆, RuCl₃·3H₂O, and Ni(NO₃)₂·6H₂O, respectively, shows the higher current density, corresponding to the higher catalytic activity.

Studies on Thickness Swelling Mechanism of Wood Particle-Polypropylene Fiber Composite by Scanning Electron Microscopy

ChanHoLee,차재경,엄영근 한국목재공학회 2002 목재공학 Vol.30 No.3

This study was carried out through scanning electron microscopy to elucidate the mechanism of thickness swelling in wood particle-polypropylene composite which is a typical way of using wood and plastic materials. For this purpose, control particleboards and nonwoven web composites from wood particle and polypropylene fiber formulations of 100:0, 70:30, 60:40, and 50:50 were manufactured at target density levels of 0.5, 0.6, 0.7, and 0.8 g/cm3. Their water absorption and thickness swelling were tested according to ASTMD 1037-93 (1995). To elucidate thickness swelling mechanism of composite through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy.From the scanning electron microscopy, thickness swelling of composite was thought to be caused by the complicated factors of degree of built-up internal stresses by mat compression and/or amount of wood particles encapsulated with molten polypropylene fibers during hot pressing. In the composites with wood particle contents of 50 to 60% at target densities of 0.5 to 0.8 g/cm3 and with wood particle content of 70% at target densities of 0.5 to 0.7 g/cm3, thickness swellings seemed to be largely dependent upon the restricted water uptake by encapsulated wood particles with molten polypropylene fibers. Thickness swelling in the composite with wood particle content of 70% at target density of 0.8 g/cm3, however, was thought to be principally dependent upon the increased springback phenomenon by built-up internal stresses of compressed mat.

Measurement and Compensation of Spring-back of a Hybrid Composite Beam

Jung, Woo-Kyun,Chu, Won-Shik,Ahn, Sung-Hoon,Won, Myung-Shik Sage Publications 2007 Journal of composite materials Vol.41 No.7

<P>Fiber-reinforced composite materials have been advanced in various applications for their excellent mechanical and electromagnetic properties. On their manufacturing processes, however, thermo-curing inherently produces the undesired thermal deformation, so-called spring-back, mainly caused by temperature drop from the process temperature to room temperature. In order to fabricate designed part geometry, the spring-back must be understood especially in hybrid composites consisting of distinct groups of different materials. In this research, the spring-back of a hybrid composite beam is measured by a series of experiments, and is predicted by the classical lamination theory (CLT) and finite element analysis (ANSYS). To confirm the predicted spring-back, {glass fiber/epoxy} + {carbon fiber/epoxy} asymmetric hybrid composites are fabricated under various conditions such as cure cycle, laminate thickness, stacking sequence, and curing sequence. The results from CLT and FEA agree well with the experimental data, but the spring-back cannot be removed completely. To fabricate flat hybrid composite beams, a web-based spring-back compensation service is developed. The CLT-based code allows the user to predict spring-back and to fabricate a mold that compensates spring-back.</P>

Electrochemical activities of Pt–Ru–Co and Pt–Ru–Ni electrocatalysts supported by a carbon fiber web

김지혜,Beta Zenia Poliquit,남호성,김상헌,이용민,김광만,고장면 한국물리학회 2012 Current Applied Physics Vol.12 No.1

Dynamic cyclic voltammetry is performed as functions of cycle number and potential window for the electrodeposition of PteRueCo and PteRueNi catalysts on a carbon fiber (CF) web. Surface morphologies of the electrodeposited catalysts are observed by a scanning electron microscope. The electrochemical activity in methanol oxidation is examined by the cyclic voltammetry using a mixed aqueous solution of methanol as an electrolyte component. As the cycle number increases, both the current density and the amount of the electrodeposited metallic particles on the CF web are increased. The PteRueNi/CF catalyst prepared in the potential range of 0.6 to 0.2 V and from the 1:2:2 mixed solution of H2PtCl6,RuCl3·3H2O, and Ni(NO3)2·6H2O, respectively, shows the higher current density, corresponding to the higher catalytic activity.

직방형 극세사를 사용한 스펀레이스 복합부직포의 물리적 특성에 관한 연구

이명수,심현주,Lee Myung-Soo,Shim Hyun-Joo 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.1

An isotropic fiberweb was manufactured with a sheet forming machine using directly spun microfibers. The fiberweb was interlaced through a water jet process to bind its constituent fibers. The process variables that affect the physical properties of the spunlace fabrics were investigated. The optimal processing conditions for the wetlaid web were determined and the detailed optimum conditions of spun lace nonwovens were as follows: fiber length was 10 mm, type of dispersing agent was non ionic surfactant, and the concentration of dispersing agent was 0.3 ml/l. Also the spilt type of microfiber was used to make nonwoven fabrics in same operation conditions. The experimental results showed that there were minor differences for the two type of nonwovnes in the hand values measured by KES-F system. However, the tensile and the tear strengths of directly spun nonwovnes were superior to split ones. Considering the durability, cost, and productivity, the directly spun nonwovens are prospective in furnishing and shoe markets.

Carding 공정을 사용한 rCF/PA6 Hybrid Web의 제조 및 활용 연구

최문우,이주희,허몽영 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.0