• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.213-214
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• 2023

The burden of housing heating costs has increased as energy prices such as global oil prices (28.1%), LNG (38%) and minerals (100%) have soared due to the Ukraine crisis. Accordingly, an electrically conductive cement composites had developed using waste carbon materials such as waste cathode materials, waste CNTs, and waste carbon fibers, and the heat generation performance was evaluated.

• Composites Research
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• v.35 no.2
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• pp.69-74
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• 2022

In this study, the conductive paste used in a wide range such as wiring in the electronic packaging field, the automobile industry, and electronic products is manufactured under various process conditions due to the simplicity of the process, and then the thermal, mechanical, and electrical characteristics are analyzed and simulation studies are conducted to optimize the process. to establish the conditions of the conductive paste manufacturing process. First, a conductive paste was prepared by setting various types of binder resin, an essential component of the conductive paste, and characteristics such as thermal conductivity, tensile strength, and elongation were analyzed. Among the binder resins, the conductive paste applied with a flexible epoxy material had the best physical properties, and a simulation study was conducted based on the physical property data base of the conductive face. As a result of the simulation, the best physical properties were exhibited when the Ag flake volume fraction was 60%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.2
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• pp.61-67
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• 2006

Dielectric and conductive frequency spectra in 0.01 Hz-13 MHz range have been measured for the composite consisting of PZT inclusions dispersed in $LiCIO_{4}$-doped polyerhylene 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 dielectric function and we could obtain various parameters related to the above two kinds of polarizations and dicussed about the parameters.

• 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.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.199-202
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• 2002

Interfacial properties and electrical sensing for fiber fracture in carbon and SiC fibers/epoxy composites were investigated by the electrical resistance measurement and fragmentation test. As fiber-embedded angle increased, interfacial shear strength (IFSS) of two-type fiber composites decreased, and the elapsed time was long to the infinity in electrical resistivity. The initial slope of electrical resistivity increased rapidly to the infinity at higher angle, whereas electrical resistivity increased gradually at small angle. Furthermore, both fiber composites with small embedded angle showed a fully-developed stress whitening pattern, whereas both composites with higher embedded angle exhibited a less developed stress whitening pattern. As embedded angle decreased, the gap between the fragments increased and the debonded length was wider for both fiber composites. Electro-micromechanical technique can be a feasible nondestructive evaluation to measure interfacial sensing properties depending on the fiber-embedded angle in conductive fiber reinforced composites.

• Macromolecular Research
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• v.12 no.1
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• pp.53-62
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• 2004

We have prepared polymer composites of low-density polyethylene (LDPE) and ionomers (Surlyn 8940) containing polar segments and metal ions by melt blending with carbon black (CB) as a conductive filler. The resistivity and positive temperature coefficient (PTC) of the ionomer/LDPE/CB composites were investigated with respect to the CB content. The ionomer content has an effect on the resistivity and percolation threshold of the polymer composites; the percolation curve exhibits a plateau at low CB content. The PTC intensity of the crosslinked ionomer/LDPE/CB composite decreased slightly at low ionomer content, and increased significantly above a critical concentration of the ionomer. Irradiation-induced crosslinking could increase the PTC intensity and decrease the NTC effect of the polymer composites. The minimum switching current (Ι$\sub$trip/) of the polymer composites decreased with temperature; the ratio of Ι$\sub$trip/ for the ionomer/LDPE/CB composite decreased to a greater extent than that of the LDPE/CB composite. The average temperature coefficient of resistance (${\alpha}$$\sub$T/) for the polymer composites increased in the low-temperature region.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.51-56
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• 2004

Conductive polymer blends and composites are widely used for different safety application such as electrostatic charge dissipation(ESD), electromagnetic interference(EMI) shielding, electrostatic prevention and safety chemical sensor. In order to prepare a impedance-type humidity sensor that is durable at high humidities and high temperature, electically conductive polymer blends based on diallyldimethylammonium chloride(DADMAC) and epoxy were prepared in this study. The polymer blends type conductive ionomer exhibits reaction each other DADMAC and epoxy in FT-IR and DSC analysis. The blends material was traced by new peak at 1600cm-1 and appeard improvement of thermal resistance by melting point shift. Alumina substrate was deposited a pair of gold electrodes by screen printing. The blend material were spin-coated with a thin film type on the surface of alumina substrate. The polymer bleld type sensor exhibits a linear impedance increasing better than DADMAC coated humidity sensor. Also it shows good sensitivity, low hysteresis and durability against high humidity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.500-504
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• 2020

Heating films were prepared with composites of poly (methyl methacrylate) and conductive graphite. The as-prepared composite was deposited on a PET film and then fabricated using a bar coater to produce a film with uniform thickness. Copper electrodes were attached to both ends of the as-prepared film, and the heating characteristics of the film were analyzed while applying a DC voltage. The electrical conductivity and heating temperature of the heating films depended on the size, structure, content, and the dispersion characteristics of the graphite in the composite. The thermal energy was adjusted by controlling the electrical energy, based on the Joule heating theory. The electrical resistance of the film was altered in proportion to Ohm's law, and the heating temperature was changed according to the structure of the film (interelectrode spacing or electrode length) and the conductive graphite content. When the content of conductive graphite in the film increases, the electrical resistance decreases, and the heating temperature increases; however, there is no significant change above a certain content (50%).

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.64-68
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• 2020

In this study, metal copper clad laminate can be prepared using epoxy composite filled with thermally conductive fillers. In order to improve the thermal conductivity of epoxy composites, it is important factor to form conductive networks through appropriate packing of conductive fillers in epoxy composite matrix and to decrease the amount of thermally resistant junctions involving a epoxy composite matrix layer between adjacent filler units. This is because epoxy has a thermal conductivity of only 0.2-0.3W, so in order to maintain high thermal conductivity, thermally conductive fillers are connected to each other, so that the gap between particles can be reduced to reduce thermal resistance. The purpose of this study is to find way to achieve highly thermally conductive in the epoxy composite matrix filled with Al₂O₃ and Boron Nitride(BN) filler by filler loading and uniform dispersion. As a results, the use of Al₂O₃/BN hybrid filler in epoxy matrix was found to be effective in increasing thermal conductivity of epoxy composite matrix due to the enhanced connectivity offered by more continuous thermally conductive pathways and uniform dispersion without interfacial voids in epoxy composite matrix. In addition, surface treatmented s-BN improves the filler dispersion and adhesion between the filler and the epoxy matrix, which can significantly decrease the interfacial thermal resistance and increase the thermal conductivity of epoxy composite matrix.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.543-550
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• 2011

Conductive SiC-$ZrB_2$ composites were produced by subjecting a 40:60 (vol%) mixture of zirconium diboride (ZrB2) powder and ${\beta}$-silicon carbide (SiC) matrix to spark plasma sintering (SPS). Sintering was carried out for 5 min in an argon atmosphere at a uniaxial pressure and temperature of 50 MPa and $1500^{\circ}C$, respectively. The composite sintered at a heating speed of $25^{\circ}C$/min and an on/off pulse sequence of 12:2 was denoted as SZ12L. Composites SZ12H, SZ48H, and SZ10H were obtained by sintering at a heating speed of $100^{\circ}C$/min and at on/off pulse sequences of 12:2, 48:8, and 10:9, respectively. The physical, electrical, and mechanical properties of the SiC-$ZrB_2$ composites were examined and thermal image analysis of the composites was performed. The apparent porosities of SZ12L, SZ12H, SZ48H, and SZ10H were 13.35%, 0.60%, 12.28%, and 9.75%, respectively. At room temperature, SZ12L had the lowest flexural strength (286.90 MPa), whereas SZ12H had the highest flexural strength (1011.34 MPa). Between room temperature and $500^{\circ}C$, the SiC-$ZrB_2$ composites had a positive temperature coefficient of resistance (PTCR) and linear V-I characteristics. SZ12H had the lowest PTCR and highest electrical resistivity among all the composites. The optimum SPS conditions for the production of energy-friendly SiC-$ZrB_2$ composites are as follows: 1) an argon atmosphere, 2) a constant pressure of 50 MPa throughout the sintering process, 3) an on/off pulse sequence of 12:2 (pulse duration: 2.78 ms), and 4) a final sintering temperature of $1500^{\circ}C$ at a speed of $100^{\circ}C$/min and sintering for 5 min at $1500^{\circ}C$.