• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.369-374
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• 2008

Two types of conductive materials are selected and their applicable properties are investigated so as to give the capability of self-diagnosis of fracture in composite mortar, concrete and reinforced concrete. In this study, for giving selfdiagnosis capability, the powder of cokes and milled carbon fiber as conductive materials are selected and intermixed with mortar, concrete and reinforced concrete. After examining change in the value of electric resistance before and after the occurrence of cracks at each flexural load-stage in composite mortar, concrete or reinforced concrete, the relationships of each factors (electric resistance, crack and flexural load) are analyzed. As the results, it can be recognized that conductive materials with powder of cokes and milled carbon fiber can be applied for self-diagnosis of flexural fracture in composite mortar, concrete and reinforced concrete specimen.

• Polymer(Korea)
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• v.24 no.5
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• pp.673-681
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• 2000

Electrically conductive composites have been prepared by treating fabrics with oxidizing agent and exposing them to aniline, which deposited a substantial amount of conductive polymer within the interstices of the material. However the conductivity of the composite fabrics was limited by the irregular deposition of the conductive polymer layer. To improve the conductivity of polyaniline/nylon 6 composite fabrics, we modified the surface characteristics of nylon 6 fabrics by various plasma treatments and increased diffusion and adsorption of aniline by ultrasonic treatments. By the oxygen plasma treatment, attachment of functional groups such as C-O and C-OH increased on the surface of nylon 6 fiber, which promoted adhesion to polyaniline resulting in the higher add-on and electrical conductivity. Electrical conductivities of polyaniline/nylon 6 composite fabrics were highly increased by ultrasonic treatment, which assisted the diffusion of aniline into the inside of nylon fabrics by cavitation and vibration. Also, the effects of monomer concentration and the number of deposition cycles on the nylon 6 fabric conductivity Were investigated. As a result, the fabric conductivity increased with the monomer concentration and the number of polymerization deposition cycles.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.257-260
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• 2005

Graphite reinforced conductive polymer composites were fabricated by the compression molding technique. Graphite powder was mixed with an phenol resin to impart electrical property in composites. The ratio and particle size of graphite powder were varied to investigate electrical conductivity of cured composites. In this study, graphite reinforced conductive polymer composites with high filler loadings(>66wt.%) were manufactured to accomplish high electrical conductivity. With increasing the loading ratio of graphite powder, the electrical conductivity and flexural strength increased. However. above 80wt.% filler loadings, flexural strength decreased due to lack of resin. Regardless of graphite particle size, electrical conductivity wasn’t varied. On the other hand, with decreasing particle size, flexural strength increased due to high specific surface area.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.146-151
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• 2013

Carbon nanofibers (CNFs) are electrically conductive. When CNFs are used as fillers in resin, this electrical conductivity can be yielded without adversely affecting the mechanical properties of the resin. When an elastomer is adopted as the resin, a conductive elastomer can then be produced. Due to its flexibility and conductive properties, a large strain sensor based on changes in resistivity may be produced, for strain sensing in flexible structures. In this study, a patch-type large strain sensor using resistivity change in a CNF/elastomer composite was proposed. The measurement limits of the sensor were investigated experimentally, and the limit was found to be 40%, which greatly exceeded the limits of conventional metal-foiled strain gages. Also, the proposed CNF/elastomer large strain sensor can be used to measure flexible materials, while conventional strain gages cannot be used to measure such strains.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1838-1840
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• 2005

Dielectric and conductive spect frequency spectra in a $1Hz{\sim}13MHz$ range have been measured for the composite consisting of PZT inclusions dispersed in a $LiClO_4$ doped polyethylene oxide(Li_PEO) matrix with various volume fractions. The dielectric and conductive spectra of the composites revealed the relaxations related with electrode polarization and interfacial polarization The observed spectra were reproduced using the empirical function and we could obtain vairous parameters related to electrode polarization and interfacial polarization.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.2
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• pp.326-334
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• 1999

Polyaniline(PAn)-nylon 6 composite fabrics were prepared by immersing the nylon 6 fabrics in 100% distilled aniline for specified diffusion time and drawn out. Then the excess aniline on the fabric surface was blotted and successive polymerization was initiate by immersing them into oxidant and dopant solution for in situ polymerization of polyaniline. Consequently highly conductive PAn-nylon 6 composite fabrics could be obtained and the conductivity reaches as high as 10-2 S/cm. The maximum conductivity was obtained when the fabric was immersed in 100% aniline at 4$0^{\circ}C$ for 3hours and polymerization was proceeded in 0.25M ammonium peroxydisulfate solution at 5$^{\circ}C$ for 1hour.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.933-938
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• 2000

Concrete has been used for many years as a composite material that has excellent mechanical properties and durability for construction. However, concrete is a poor electrical conductor, especially under dry conditions. Concrete that is excellent in both mechanical and electrical conductivity properties may have important applications in the electrical, electronic, military and construction industry(e.g. for de-icing road from snow). The purpose of this investigation is to improve the electrical conductive of cement mortar preparared with coke dust, graphite, carbon black and carbon fiber as filler. From the test result, as the content of electrically conductive material increased, fluidity and strength decreased but resistivity decreased. The resistivity of electrical conductive cement mortar is effect by water/cement, and aggregate. Cement mortar containing carbon fiber has the best electrical properties considering strength. From this study, it is enough to assure the use of carbon fiber, carbon black and graphite as a conductive filler for electrical conductive cement mortar.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.203-214
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• 2022

Thermoelectric (TE) heating and cooling devices, which are able to directly convert thermal energy into electrical energy and vice versa, are effective and have exhibited a potential for energy harvesting. With the increasing consumer demands for various wearable electronics, organic-based TE composite materials offer a promise for the TE devices applications. Conductive polymers are widely used as flexible TE materials replacing inorganic materials due to their flexibility, low thermal conductivity, mechanical flexibility, ease of processing, and low cost. In this review, we briefly introduce the latest research trends in the flexible TE technology and provide a comprehensive summary of specific conductive polymer-based TE material fabrication technologies. We also summarize the manufacture for high-efficiency TE composites through the complexation of a conductive polymer matrix/inorganic TE filler. We believe that this review will inspire further research to improve the TE performance of conductive polymers.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.258-262
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• 2001

The contact resistivity was correlated with IFSS and microfailure modes in conductive fiber/cement composites electro-pullout and AE. As IFSS increased, the number of AE signals increased and the contact resistivity increased latter to the infinity. In dual matrix composite (DMC) test and AE, the number of signals with high amplitude and energy in g]ass fiber composite is significantly larger than that of no-fiber composite. Many vertical and diagonal cracks were observed in glass fiber and no-fiber composite under tensile test, respectively. Electro-micromechanical technique and AE can be used efficiently for sensitive nondestructive (NDT) evaluation and to detect microfailure mechanisms in various conductive fibers reinforced brittle and nontransparent cement composites.

• Journal of the Korean institute of surface engineering
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• v.53 no.4
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• pp.160-168
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• 2020

A polymer-based carbon nanomaterial composite was fabricated and characterized for the application of a thermal conductive adhesive. Low-dimensional carbon nanomaterials with excellent thermal conductivity such as carbon nanotube (CNT) and graphene were selected as a filler in the composite. Thermal, electrical and adhesive properties of the composite were investigated with respect to the morphology and content of the low-dimensional carbon nanomaterials. As a result, the composite-based adhesive fabricated by the loading of surface-treated MWCNTs of 0.4 wt% showed uniform dispersion, moderate adhesion and effective heat dissipation properties. Finally, it was confirmed through the thermal image analysis of LED module that the temperature reduction of 10℃ was achieved using the fabricated composite adhesive with MWCNT-6A. Expecially, heat dissipation performance of the optimized composite adhesive was evident at the hot spot in the module compared to other samples mixed with graphene or different MWCNT loading ratios.