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Wood Fiber-Thermoplastic Fiber Composites by Turbulent Air Mixing Process(II) - Effect of Process Variables on The Mechanical Properties of Composites - (난기류 혼합법을 이용한 목섬유-열가소성 섬유 복합재에 관한 연구(II) - 공정변수가 복합재의 기계적 성질에 미치는 영향 -)

  • Yoon, Hyoung-Un;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.25 no.3
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    • pp.58-65
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    • 1997
  • This research was carried out to evaluate the effect of process variables on mechanical properties of the wood fiber-thermoplastic fiber composites by turbulent air mixing method. The turbulent air mixer used in this experiment was specially designed in order to mix wood fiber and thermoplastic polypropylene or nylon 6 fiber, and was highly efficient in the mixing of relatively short plastic fiber and wood fiber in a short time without any trouble. The adequate hot - pressing temperature and time in our experimental condition were $190^{\circ}C$ and 9 minutes in 90% wood fiber - 10% polypropylene fiber composite and $220^{\circ}C$ and 9 minutes in 90% wood fiber 10% nylon 6 fiber composite. Both in the wood fiber - polypropylene fiber composite and wood fiber- nylon 6 fiber composite, the mechanical properties improved with the increase of density. Statistically, the density of composite appeared to function as the most significant factor in mechanical properties. Within the 5~15% composition ratios of polypropylene or nylon 6 fiber to wood fiber, the composition ratio showed no significant effect on the mechanical properties. Bending and tensile strength of composite, however, slightly increased with the increase of synthetic fiber content. The increase of mat moisture content showed no significant improvement of mechanical properties both in wood fiber - polypropylene fiber composite and wood fiber nylon 6 fiber composite. Wood fiber - nylon 6 fiber composite was superior in th mechanical strength to wood fiber-polypropylene fiber composite, which may be related to higher melt flow index of nylon 6 fiber(22g/10min) than of polypropylene fiber(4.3g/10min).

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Wood Fiber-Thermoplastic Fiber Composites by Turbulent Air Mixing Process(I) - Effects of Process Variables on the Physical Properties of Composites - (난기류 혼합법을 이용한 목섬유-열가소성 섬유 복합재에 관한 연구(I) - 공정변수가 복합재의 물리적 성질에 미치는 영향 -)

  • Yoon, Hyoung-Un;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.24 no.3
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    • pp.101-109
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    • 1996
  • Effects of process variables were evaluated in physical properties of the wood fiber-thermoplastic fiber composites using nonwoven web method. Turbulent air mixer using compressed air was employed to mix wood fiber with two types of thermoplastic polypropylene and nylon 6 fibers. The optimal hot press temperature and time were found to be $190^{\circ}C$ and 9 minutes in wood fiber-polypropylene fiber composite and to be $220^{\circ}C$ and 9 minutes in wood fiber-nylon 6 fiber composite. As the density of wood fiber-polypropylene fiber composite and wood fiber-nylon 6 fiber composite increased, the physical properties were improved The density appeared to be the most significant factor on physical properties in the statistical analysis. The composition ratio of polypropylene or nylon 6 fiber to wood fiber was considered not to be statistically significant factor. The thickness swelling decreased somewhat in wood fiber-polypropylene fiber composite and wood fiber-nylon 6 fiber composite as the content of synthetic fiber increased. As the increase of mat moisture content, dimensional stability was improved in wood fiber-polypropylene fiber composite but not in wood fiber-nylon 6 fiber composite.

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Effect of molding condition on tensile properties of hemp fiber reinforced composite

  • Takemura, K.;Minekage, Y.
    • Advanced Composite Materials
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    • v.16 no.4
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    • pp.385-394
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    • 2007
  • In this study, the effect of molding condition on the tensile properties for plain woven hemp fiber reinforced green composite was examined. The tensile properties of the composite were compared with those of the plain woven jute fiber composite fabricated by the same process. Emulsion type biodegradable resin or polypropylene sheet was used as matrix. The composites were processed by the compression molding where the molding temperature and its heating time were changed from 160 to $190^{\circ}C$ and from 15 to 25 min, respectively. The following results were obtained from the experiment. The tensile property of hemp fiber reinforced polypropylene is improved in comparison with polypropylene bulk. The strength of composite is about 2.6 times that of the resin bulk specimen. Hemp fiber is more effective than jute fiber as reinforcement for green composite from the viewpoint of strength. The molding temperature and time are suitable below $180^{\circ}C$ and 20 min for hemp fiber reinforced green composite. Hemp fiber green composite has a tendency to decrease its tensile strength when fiber content is over 50 wt%.

Characteristics Correlations Between Fiber-Reinforced and Interfacial Adhesion in Carbon fiber reinforced Cement composite Prepared by Slurry Method. (슬러리법에 의한 탄소섬유보강 시멘트복합체의 제조에서 보강섬유와 계면결착제와의 상관특성)

  • Choi, Eung-Kyoo
    • Journal of the Korea Institute of Building Construction
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    • v.2 no.3
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    • pp.131-138
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    • 2002
  • The objective of the study is to examine the characteristic correlations between reinforcing carbon fiber and interfacial adhesion agent since the interfacial adhesion strength between reinforcing carbon fiber and matrices is believed to be an essential element influencing the physical properties in carbon fiber reinforced cement composite using slurry method. The integrity of interfacial adhesion between reinforcing fiber and cement not only affects the quality of fiber reinforced cement composite but also influences to a large degree the physical properties of the cement composite when producing carbon fiber reinforced cement composite using slurry method. Having analyzed the physical properties 1.e., water content, tensile strength, flexural strength and flexural toughness of carbon fiber reinforced cement composite specimens, C-PAM(cation polyacrylamide) was determined to be an optimum interfacial adhesion agent. The study has also demonstrated that interfacial adhesion strength varies largely on the content and type of the reinforcing fiber. Judging from magnified view of the tensile shear cross-section using VMS(video microscope system), interfacial adhesion strength between reinforcing fiber and matrices is affected by the type of interfacial adhesion agent. According to the result of the experiments, C-PAM was determined to be an ideal interfacial adhesion agent when using carbon fiber in producing carbon fiber reinforced cement composite with the optimum content of carbon fiber being established.

Study on Interlaminar Properties of Kevlar/Spectra Intraply Hybrid Composites (보강섬유의 하이브리드화에 의한 케블라/스펙트라 복합재료의 층간 성질변화에 관한 연구)

  • Kim, Cheol;Kang, Tae-Jin
    • Textile Science and Engineering
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    • v.33 no.8
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    • pp.736-741
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    • 1996
  • Effects of intraply hybridization of the reinforced fiber on the interlaminar properties of Kevlar/spectra hybrid laminated composites have been studied. Interlaminar shear strength of the laminated composite has been reduced by intraply hybridization of the reinforced fiber. The intraply hybrid composites showed an impaired interlaminar properties including interlaminar shear strength. The hybrid composite showed higher anisotropy in thermal expansion coefficient as well as elastic modulus. These result in higher residual internal thermal stresses after curing of the composite, and this has a profound influence on the fiber/matrix interfacial strength of the composite. The interlaminar thermal residual stresses and fiber/matrix interfacial strength with the hybridizations of the reinforced fiber $\Phi$ have been analyzed. The hole drilling residual stress measuring technique has been adapted to evaluate the thermal residual stresses. Mode I edge delamination test and short beam shear test at elevated temperature have been performed to evaluate the interlaminar properties of the hybrid composite. The hybrid composite showed higher thormal residual stresses, especially the thermal residual compressive stresses which exist in the fiber directions. Tensile property of the hybrid composite had slightly increased because of the residual compressive stresses in fiber directions. The fiber/matrix interfacial strength had reduced as the hybrid composite have higher expansion in Z-direction of the composite. This results in reduced interlaminar strength of the hybrid composite.er)

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Manufacture and Engineering Evaluation of Hybrid Grid Fabrics for Seismic Reinforced Carbon Fiber Composite Yarns. I. Manufacture of Carbon Fiber Composite Yarn and Fabric Design (내진보강용 탄소섬유 복합사 하이브리드 그리드 직물 제조 및 공학적 성능 평가. I. 탄소섬유 복합사 제조 및 최적 직물 설계)

  • Yan, Yu;Cha, Ju Hee;Chai, Charles;Lee, Hyeong Ho;Jeon, Han Yong
    • Textile Science and Engineering
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    • v.55 no.4
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    • pp.280-285
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    • 2018
  • In this study, a carbon fiber composite yarn with the desired stiffness and ductility was fabricated for use in hybrid grid fabrics for seismic reinforcement, and the optimum structures of the grid fabrics were evaluated. Carbon fiber composite yarn was prepared by a double-covering process with carbon fiber/aramid fiber/high-strength PET fiber. It was confirmed that the strength of the carbon fiber composite yarn was greatly increased compared to that of carbon fiber, and the elongation increased by about 0.5%. The TPU (thermoplastic polyurethane) extrusion coating method was more suitable for the carbon fiber composite yarn than urethane impregnation for the coating process. Meanwhile, in the evaluation of yarn fineness and grid structure, thick fibers had greater strengths. When comparing the strength and elongation, the bi-directional grid showed no advantages over the unidirectional grid.

Electrical Conductivity of Carbon Fiber-Polymer Composite (Carbon 화이버-폴리머 복합체의 전기적 특성)

  • 이재연;최경만
    • Journal of the Korean Ceramic Society
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    • v.35 no.6
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    • pp.603-609
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    • 1998
  • The composites of insulating polymer filled with conducting carbon-fiber were fabricated by molding press method. To understand the fiber aspect-ratio dependence of electrical conductivity the aspect ratio was varied from 4 to 10 The percolation thresholds of transition from the insulator to the conductor de-creased as the fiber aspect ratio increased. The percolation threshold of fiber-segregated composite in this study was smaller than that of fiber-random composite shown in other study. When the electrical con-ductivity curves were fitted by general effective medium equation morphological variable(t) decreased as the fiber aspect-ratio increased.

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Physical and Mechanical Properties of Wood Fiber-Polypropylene Fiber Composite Panel

  • Kim, Jee-Woong;Eom, Young-Geun
    • Journal of the Korean Wood Science and Technology
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    • v.29 no.3
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    • pp.36-46
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    • 2001
  • This study was to find a way of reusing wood and plastic wastes, which considered as a troublesome problem to be solved in this age of mass production and consumption, in manufacturing wood fiber-polypropylene fiber composite panel. And the feasibility of this composite panel as a substitute for existing headliner base panel of automobile was also discussed, especially based on physical and mechanical performance. Nonwoven web composite panels were made from wood fiber and polypropylene fiber formulations of 50 : 50, 60 : 40, and 70 : 30, based on oven-dry weight, with densities of 0.4, 0.5, 0.6, and 0.7 g/$cm^3$. At the same density levels, control fiberboards were also manufactured for performance comparison with the composite panels. Their physical and mechanical properties were tested according to ASTM D 1037-93. To elucidate thickness swelling mechanism of composite panel 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. Test results in this study showed that nonwoven web composite panel from wood fibers and polypropylene fibers had superior physical and mechanical properties to control fiberboard. In the physical properties of composite panel, dimensional stability improved as the content of polypropylene fiber increased, and the formulation of wood fiber and polypropylene fiber was considered to be a significant factor in the physical properties. Water absorption decreased but thickness swelling slightly increased with the increase of panel density. In the mechanical properties of composite panel, the bending modulus of rupture (MOR) and modulus of elasticity (MOE) appeared to improve with the increase of panel density under all the tested conditions of dry, heated, and wet. The formulation of wood fiber and polypropylene fiber was considered not to be a significant factor in the mechanical properties. All the bending MOR values under the dry, heated, and wet conditions met the requirements in the existing headliner base panel of resin felt.

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Actuating Characteristics of a Piezoceramic fiber Composite Actuator (압전섬유 복합재 엑츄에이터의 거동 특성)

  • Koo, Kun-Hyung;Kim, Cheol
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.53-56
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    • 2001
  • Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material and actuator shape. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.

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Interfacial Properties of Electrodeposited Carbon Fiber/Epoxy Composites using Electro-Micromechanical Techniques and Nondestructive Evaluations

  • Park, Joung-Man;Lee, Sang-Il
    • Macromolecular research
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    • v.9 no.1
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    • pp.20-29
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    • 2001
  • Interfacial adhesion and nondestructive behavior of electrodeposited (ED) carbon fiber rein-forced composites were evaluated using electro-micromechanical techniques and acoustic emission (AE). The interfacial shear strength (IFSS) of the ED carbon fiber/epoxy composites was higher than that of the untreated fiber. This might be expected because of the possibility of chemical or hydrogen bonding in an electrically adsorbed polymeric interlayer. The logarithmic electrical resistivity of the untreated single-carbon fiber composite increased suddenly to infinity when fiber fracture occurred, whereas that of the ED composite increased relatively gradually to infinity. This behavior may arise from the retarded fracture time due to enhanced IFSS. In single- and ten-carbon fiber composites, the number of AE signals coming from interlayer failure of the ED carbon fiber composite was much larger than that of the untreated composite. As the number of the each first fiber fractures increased in the ten-carbon fiber composite, the electrical resistivity increased stepwise, and the slope of the logarithmic electrical resistance increased.

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