• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.63-65
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• 1989

Piezoelectric BaTiO$_3$-polymer composite were investigated for dielectric and piezoelectric properties with the barium titanate active particle size. Under the condition of the same density and ceramic volume ratio of composite, the dielectric and piezoelectric constant of composite are increasing as the ceramic particle size in composite are increasing. The surface layer model was quoted to explain these phenomena in our system and experimentally confirmed. The connectivity parameter of modified cube model of composite was calculated from the dielectric constant variation as their particle size. The connectivity parameter X and Y were 77.8% and 98.9% respectively. It means that the barium titanate particle distribution in composite nearly approach to the parallel mode. It was experimentally confirmed that the surface layer has low dielectric and nonferroelectric properties. Dielectric constant and thickness of surface layer were calculated from the equivalent circuit of composite.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.47-58
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• 2001

For finding both ways of recycling the wood and plastic wastes and solving the problem of free formaldehyde gas emission through manufacturing wood particle-polypropylene fiber composite board without addition of formaldehyde-based thermosetting resin adhesive, control particleboards and nonwoven web composite boards from wood particle and polypropylene fiber formulation of 50 : 50, 60 : 40, and 70 : 30 were manufactured at density levels of 0.5, 0.6, 0.7, and 0.8 g/$cm^3$, and were tested both in the physical and mechanical properties according to ASTM D 1037-93. In the physical properties, control particleboard had significantly higher moisture content than composite board. In composite board, moisture content decreased with the increase of target density only in the board with higher content of polypropylene fiber and also appeared to increase with the increase of wood particle content at a given target density. Control particleboard showed significantly greater water absorption than composite board and its water absorption decreased with the increase of target density. In composite board, water absorption decreased with the increase of target density at a given formulation but increased with the increase of wood particle content at a given target density. After 2 and 24 hours immersion, control particleboard was significantly higher in thickness swelling than composite board and its thickness swelling increased with the increase of target density. In composite board, thickness swelling did not vary significantly with the target density at a given formulation but its thickness swelling increased as wood particle content increased at a given target density. Static bending MOR and MOE under dry and wet conditions increased with the increase of target density at a given formulation of wood particle and polypropylene fiber. Especially, the MOR and MOE under wet condition were considerably larger in composite board than in control particleboard. In general, composite board showed superior bending strength properties to control particleboard, And the composite board made from wood particle and polypropylene fiber formulation of 50 : 50 at target density of 0.8 g/$cm^3$ exhibited the greatest bending strength properties. Though problems in uniform mixing and strong binding of wood particle with polypropylene fiber are unavoidable due to their extremely different shape and polarity, wood particle-polypropylene fiber composite boards with higher performance, as a potential substitute for the commercial particleboards, could be made just by controlling processing variables.

• Journal of the Korean Wood Science and Technology
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• v.29 no.2
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• pp.109-117
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• 2001

This research was carried out to develop the Hanji(Korean paper) sludge wood particle composite utilizing the waste sludges occurring from the making process of Hanji(Korean paper). In the research, four mixing ratios of white or black sludge to wood particle(10:90, 20:80, 30:70, and 40:60), three types of the resin adhesives(PMDI, urea and phenol resin) and three levels of the densities(0.60, 0.75 and 0.90) were designed to investigate the physical properties of Hanji(Korean paper) sludge wood particle composite. The linear expansion of Hanji(Korean paper) sludge wood particle composite was not always increased, compared to control boards. For thickness swelling, PMDI-bonded composites had the lowest value, and thickness swelling of composite was generally decreased with the increase of Hanji sludge. The water absorption of white sludge wood particle composite had no tendency, hut that of black sludge wood particle composite was decreased with an increase of mixing ratio of Hanji sludge.

• Journal of the Korean Applied Science and Technology
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• v.21 no.1
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• pp.69-75
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• 2004

In this study, various model composite latexes were synthesized using n-butyl acrylate and methyl methacrylate as comonomers by seeded multi-staged emulsion polymerization. Monodispersed model composite latex particles with size of 190 nm and polydispersity index of 1.05, which have various morphology including random copolymer particle, soft-core/hard-shell particle, hard-core/soft shell particle, and gradient-type copolymer particle, homopolymers particles were prepared. The designed morphology of model composite particles were confirmed.

• Journal of the Korean Wood Science and Technology
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• v.30 no.2
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• pp.121-127
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• 2002

This research was carried out to develop the Hanji(Korean paper) sludge·wood particle composite utilizing the waste sludges occurring from the making process of Hanji(Korean paper). At the research, four mixing ratios of white or black sludge to wood particle(10:90, 20:80, 30:70 and 40:60), three types of the resin adhesives(PMDI, urea and phenol resin) and three levels of the densities(0.60, 0.75 and 0.90) were designed to investigate the mechanical properties of Hanji(Korean paper) sludge·wood particle composite. In the white and black sludge·wood particle composites, bending properties(MOR, MOE) showed the decreasing tendency according to the increase of sludge additive, but it was clearly increased with the increase of specific gravity. Also tensile strength had the same tendency as in these bending properties. The internal bond strength of white sludge·wood particle composite had no tendency, but that of black sludge·wood particle composite was decreased as an increase of Hanji sludge additive.

• Journal of the Korean Applied Science and Technology
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• v.21 no.3
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• pp.259-266
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• 2004

Film properties of monodispersed model composite latexes with particle size of 190 nm, which consist of n-butyl acrylate as a soft phase monomer and methyl methacrylate as a hard phase monomer with different morphology was examined. Five different types of model latexes were used in this study such as random copolymer particle, soft-core/hard-shell particle, hard-core/soft-shell particle, gradient type particle, and mixed type particle. Tensile strength and tensile elongation at break of final films were evaluated. Those properties can be interpreted in terms of PBA/PMMA phase ratio and their morphology. The interfacial adhesion strength was also evaluated using $180^{\circ}$ peel strength measurement and cross hatch cutting test.

• Journal of Powder Materials
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• v.13 no.1 s.54
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• pp.39-45
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• 2006

The $Al/SiC_p$ particle reinforced composite fabricated by a powder-in sheath rolling (PSR) method was severely. deformed by the accumulative roll-bonding (ARB) process. The ARB process was performed up to 8 cycles at ambient temperature without lubricant. The ARBed composite exhibited an ulbricant. grained structure similar to the other ARBed bulky materials. Tensile strength of the composite increased gradually with the number of ARB cycles, but from the 6th cycle it rather decreased slightly. These characteristics of the composite were somewhat different from those of Al powder compact fabricated by the same procedures. The difference in microstructure and mechanical properties between Al powder compact and the composite was discussed.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.676-679
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• 2010

Nano composite particles were synthesized from a bulk ZrVFe alloy ingot by transferred DC thermal plasma. Effects of plasma gas flow rate on the characteristics of the produced nano composite particles were investigated. The characteristics of the synthesized powder were analyzed by field scanning electron microscopy (FE-SEM), light scattering particle size analyzer (PSA), energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), and Brunauer-Emmett-Teller (BET) surface area analyzer. As the flow rate of plasma gas increased from 20 L/min to 40 L/min, the average particle size decreased from 91 nm to 55 nm, the particle size distribution became narrower, the surface area increased from $200\;m^2/g$ to $255\;m^2/g$, the particle composition was nearly unaffected, and the particle crystallinity was improved.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.48-58
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• 2002

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.

• Journal of Adhesion and Interface
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• v.11 no.3
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• pp.112-119
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• 2010

Poly(methyl methacrylate)/poly(butyl acrylate) PMMA/PBA core-shell composite particles were prepared by the emulsion polymerization of MMA and BA in the presence of different concentration of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the measured conversion and particle size distribution, morphology, average molecular weight distribution, observation of film formation and particle formation, glass transition temperature and physical properties of polymerized core-shell composition particles for using adhesive binder. When the concentration of 0.03 wt% surfactant, the conversions of PMMA and PBA core polymerization are excellent as 95.8% for PMMA core and 92.3% for PBA core. Core-shell composite particles are obtained 90.0% for PMMA/PBA core-shell composite particles and 89.0% for PMMA/PBA core-shell composite particles. It is considered that the core and shell particles are polymerized to be confirmed FT-IR spectra and average molecular weight measured with a GPC, formation of the composite particles is confirmed by the film formation from normal temperature, and composition of inside and outside of the composite particle is confirmed by TEM photograph. The synthesized polymer has two glass transition temperatures, suggesting that the polymer is composed of core polymer and shell polymer unlike general copolymers. It is considered that each core-shell composite particle can be used as a high functionality adhesion binder by the measurement of tensile strength and elongation.