• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.670-675
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• 2010

Inorganic-organic hybrid material such as vinyl-nano sized silica ball was synthesized by acrylo-alkoxysilane and nano silica ball with different particle size. And then they were formulated into acrylic-melamine clearcoat. This material is fully characterized with various analytical methods and applied for strength measurement. The glossy effect, matting effect and anti-scratching properties of materials were investigated for further growth and maintenance. When the particle size of nano silica ball is 20~30 nm, the glossy retain effect was increased by 7% compared to bare acrylic-melamine clearcoat. When a commercially available silica Aerosil 200 (Hydrophilic fumed silica, average particle size 12 nm, Degussa) react with vinyl alkoxysilane vinyl-fumed silica complex form. The vinyl-fumed silica along with clearcoat increases only 2% increase at glossy retain. Nano-scratch test results also support the glossy retain effect of vinyl nano-sized silica ball in clearcoat.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.69-78
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• 2007

The mechanical properties of wood flour, Hwangto (325 and 1,400 mesh per 25,4 mm) and coupling agent-reinforced HDPE composites were investigated in this study. Hwangto and maleated polyethylene (MAPE) were used as an inorganic filler and a coupling agent, respectively. The addition of Hwangto and MAPE to virgin HDPE also increased the Young's modulus in the smaller degree. The addition of wood flour and Hwangto to virgin HDPE increased the tensile strength, due to the high uniform dispersion of HDPE by high surface area of Hwangto in HDPE and wood flour. MAPE also significantly increased the tensile strength. When wood flour was added, there was no notable difference on the tensile properties, in terms of Hwangto particle size. Hwangto also improved the flexural modulus and strength of reinforced HDPE composites. With different particle sizes of Hwangto, there was no considerable difference in flexural modulus and strength of reinforced HDPE composites. The addition of Hwangto showed slightly lower impact strength than that of wood flour. However, the particle size of Hwangto showed no significant effect on the impact strength of reinforced composites. In conclusion, reinforced HDPE composites with organic and inorganic fillers provide highly improved mechanical properties over virgin HDPE.

• Elastomers and Composites
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• v.43 no.4
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• pp.230-240
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• 2008

In order to synthesize polymer particle containing inorganic material, styrene and nbutylmetacrylate were copolymerized with alumina by dispersion polymerization. The ratio in weight of styrene to n-butyl methacrylate was 3:1. Poly(N-vinyl pyrrolidon) and 2,2'-azobis(isobutyronitrile) were added as stabilizer and as initiator, respectively. The change of particle size was investigated with concentration of initiator, the type of medium, the mixed solubility parameter (${\delta}_{mix}$) of medium, and coupling agent. The enhancement in concentration of initiator resulted in slight increase of particle size. The increase of polarizability in medium also yielded the increase of particle size. In case of changing the ratio of isopropanol to distilled water, we could find relationship of $[{\delta}_{mix}]^{-4.01}\;{\propto}$ particle size and $[{\delta}_{mix}]^{-0.83}\;{\propto}$ particle size distribution(PSD). The type and the concentration of coupling agent showed no effect on the particle size and PSD.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.511-515
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• 2014

The thermodynamic instability of bubbles in wet-foam colloidal suspension is due to the substantial area of their gas/liquid interface. Several physical processes lead to gas diffusion from smaller to larger bubbles, resulting in a coarsening and Ostwald ripening of wet foam. This includes a narrowing of the bubble size distribution. The distribution and microstructure of porous ceramics, the adsorption free energy and Laplace pressure of $Al_2O_3$ particle-stabilized colloidal suspension, and $SiO_2$ content were investigated for tailoring the bubble size. Wet-foam stability of more than 80% is related to the degree of hydrophobicity with contact angles of $62-70^{\circ}$ achieved from the surfactant. The contact angle replaces part of the highly energetic interface and lowers the free energy of the system. This leads to an apparent increase in the surface tension (26-33 mN/m) of the colloidal suspension.

• Polymer(Korea)
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• v.34 no.1
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• pp.8-13
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• 2010

The physical properties of polymeric foams depend on the density of foams, physical properties of base polymers, the content of open cells, and cell structures including the size and its distribution, the shape of cell, and the thickness of skin layer. The foam density is affected by the chemistry of raw materials, the concentration of crosslinking agent and the blowing agent as well as the operating parameters during production process. In this study, the basic formulations of foams are composed of polyester polyol, MDI, amine catalyst, tin catalyst, silicone surfactant, and water. Cross-linking density of polyurethane was increased by using chain extenders. Also, the mechanical properties of polyurethane foam were improved by using the inorganic fillers (silica 1,2 and talc 1,2) having different $SiO_2$ contents and particle sizes. We investigated the properties of modulus, tensile strength, compressive strength and hardness of foams obtained by changing kind of inorganic filler and chain extender, and observed the distribution of inorganic filler as well as variation of cell size within the foams by electron microscopy.

• Environmental Engineering Research
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• v.19 no.3
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• pp.229-240
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• 2014

Rain events are extremely important for phosphorus (P) dynamics in rivers since large portions of annual river P loads can be transported in particulate forms during only a few major events. Despite their importance, a precise estimation of P contribution in river sediments after rainy seasons has rarely been reported. This study estimated the longitudinal variation in the concentrations of different inorganic P fractions in bed sediments of the South Han River over a rainy season, through using the sequential extraction method. Non-apatite P was the dominant form, representing more than 60% of total inorganic P (TIP) content in sediments. Although no significant variation of TIP contents was observed, the proportion of bioavailable P in TIP pools decreased after the rainy season. The concentrations of individual inorganic P fractions ($NH_4Cl-P$, $NH_4F-P$, NaOH-P, and $H_2SO_4-P$) were significantly different across sites and after the rainy season (p < 0.05, two-way ANOVA). $NH_4F-P$ and NaOH-P concentrations in sediments increased in a downstream direction. After the rainy season, $NH_4Cl-P$ concentrations in sediments decreased whereas $NH_4F-P$ and $H_2SO_4-P$ concentrations increased. The redistribution of individual P fractions in sediments observed after rainy seasons were possibly due to the changing contribution of various sources of runoff and the variation in flow related particle size. Current estimation of P in bed sediments of the South Han River suggests a lower potential of internal P loading from sediments after the rainy season.

• Polymer(Korea)
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• v.32 no.6
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• pp.549-554
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• 2008

In order to synthesize polymer particle containing inorganic material, styrene and n-butylmethacrylate were copolymerized with alumina by dispersion polymerization. The weight ratio of styrene to n-butylmethacrylate was 3 : 1. A poly(N-vinyl pyrrolidon) was added as stabilizer. 2,2'-AzobisCisobutyronitrile) and 3-methacryloxypropyl trimethoxysilane were used as initiator and coupling agent, respectively. The weight ratio of 70 : 30 of isopropanol to distilled water was used as dispersion medium. According to the TEM measurement, we could confirm that alumina was dispersed into the polymer particle. The increase 'of concentration of alumina resulted in enhancement of particle size, but decreased its distribution. By the XRD method, it was found that the increase of alumina concentration showed the increase of intensity in peak and the increased 2$\theta$ value. From the TGA measurement, the increase of alumina concentration caused high heat resistance of the polymer. With respect to the type of initiator, the longer half life of initiator, the smaller particle size. We also found that the increase of particle stabilizer concentration made the decreased of particle size due to the accelerated generation of polymer particle in the early stage of reaction.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.163-167
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• 2016

Inverter surge resistant enameled wire was prepared with an organic/inorganic hybrid nanocomposite, and the effect of ambient temperature on the insulation lifetime of the enameled wire in the form of twisted pair was studied by a withstanding voltage tester. The organic polymer was Polyesterimide-polyamideimide (EI/AI) and the inorganic material was a Nano-sized silica (average particle size : 15 nm). The enamel thickness was 50 μm and the ambient temperature was 100, 150, 200, and 250, respectively. Transmission electron microscopy (TEM) observation showed that Nano-sized Silica were evenly dispersed in EI/AI. There were many air gaps in a twisted pair, therefore, when voltage was applied to the twisted pair, enamel erosion took place in the air gap area because of partial discharge accordi, ng to Paschen’s law. As ambient temperature increased, insulation lifetime decreased according to Arrhenius relationship, which was explained by the increasing mobility of polymer chains in EI or AI. And insulation breakdown voltage value at 10 kHz was 1,864.5 sec (31.1 min), which is 1.9 times higher than at 20 kHz, 981.6 sec (16.4 min).

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.77-84
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• 2017

In this study, Poly-urethane acrylate (PUA) was synthesized by the reaction between Polycaprolactonetriol (PCLT) and Isophorone dissocyanate (IPDI) and hybridized with inorganic materials. Tetraethylortho silicate (TEOS) and nano clay (Closite 20A) were used as inorganic particles. For the hybridization of TEOS with PUA, sol-gel method is used, in which TEOS is made into spherical particle in the firsthand. In the case of Nano clay, hybridization is carried out through the dispersion as Nano clay has a layered structure. The solution of PUA hybrid was made into a film after UV curing and its thermo and electrical properties were measured. The experimental analysis and result demonstrate that the PUA hybrid shows an improved thermal properties and lower dielectric constant than that of the non-hybrid PUA. The trend of improved properties was different depending on structure of inorganic materials.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.3
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• pp.107-114
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• 2016

Terra Alba Wallpaper was manufactured by coating inorganic terra alba paint on white base paper, and the surface of the coated layers were microscopically observed. Eco Terra Alba used the functional wall paper in this study was prepared by mixing inorganic Terra Alba and calcium carbonate. Terra Alba showed particle shape. The concentration of inorganic components, pH, and the viscosity of the coating solution were 92.0%, 7.82, 1286 cPs, respectively. The bar coater whit No 3 wire resulted in the least thickness of wet coating layer and coating thickness such $22.5{\mu}m$ with covered all the surface. Bar coater with No. 12 wire leaded to $48.4{\mu}m$ thickness. The coating layers above $43{\mu}m$ thickness showed the cracks on the wall paper surface after coating.