• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.558-565
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• 2019

In this study, dimethyl silicone oil and liquid paraffin were combined and subsequently emulsified; the resulting mixture was innovatively incorporated into desulfurized gypsum to resolve its drawback of a poor water resistance. The waterproof mechanism of the composite emulsion and liquid paraffin emulsion with mass fractions of 1%, 2%, 3%, and 4% were investigated. The effect of the desulfurized gypsum on the waterproof performance and basic mechanical properties were also investigated. The configuration of the composite waterproofing agent was characterized by FTIR and ¹HNMR. The results showed that, compared with the traditional liquid paraffin emulsion-based waterproofing agent, the softening coefficient of the silicone oil paraffin composite emulsion-based water-repellent agent was increased by 60% and attained a value of 0.89. Combined with the waterproof mechanism and microscope morphology analysis of gypsum hydration products, the improvement in the water resistance of water resistance was primarily attributed to the formation of a silicone hydrophobic membrane between the crystals of the gypsum block; this ensured that water could not penetrate the crystal.

• Polymer(Korea)
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• v.25 no.5
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• pp.617-624
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• 2001

The core-shell composite latexes were synthesized by stage emulsion polymerization of methyl methacrylate (MMA) and styrene (St) with ammonium persulfate after preparing monomer pre-emulsion in the presence of anionic surfactant. However, in preparation of core-shell composite latex, several unexpected results are observed, such as, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve the disadvantages, We study the effect of initiator concentrations, surfactant concentrations, and reaction temperature on the core-shell structure of polymethyl methacrylate/polystyrene and polystyrene/polymethyl methacrylate. Particle size and particle size distribution were measured using particle size analyzer, and the morphology of the core-shell composite latex was determined using transmission electron microscope. Glass temperature was also measured using differential scanning calorimeter. To identify the core-shell structure, pH of the two composite latex solutions were measured.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.682-689
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• 2018

In this paper, the stability criteria of cosmeceuticals emulsion containing Broussonetia kazinoki extracts was established using the central composite design model. As optimization conditions of the emulsification using the central composite design model, concentrations of the emulsifier and emulsion stabilizer were used as a quantitative factor while emulsion stability index (ESI) and polydispersity index (PDI) were used as a reaction value. The targeted values of ESI and PDI were estimated as over 60% and the minimum number, respectively. Optimized concentrations of the emulsifier and emulsion stabilizer were 3.73 and 3.07 wt%, respectively, from the emulsification optimization based on ESI and PDI values. The estimated reaction values of ESI and PDI were 60% and 0.585, respectively. As concentrations of the emulsifier and emulsion stabilizer increased, the stability of the emulsion prepared tended to increase. The emulsifier was one of the most influential factors for ESI than the emulsion stabilizer. On the other hand, the PDI value was similarly affected by both the emulsion and emulsion stabilizer. The ESI of the cosmeceuticals emulsion prepared under experimental conditions deduced from the central synthesis planning model showed at least about 45% of the stability. However, all of the emulsions were separated after 4 weeks from the initial preparation. When the concentration of the emulsifier was more than 3.72 wt%, the ESI value was over 60%. Also the layer separation rate decreased with increasing the emulsion stabilizer concentration.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3303-3306
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• 2014

A facile and effective approach has been developed to prepare hybrid hollow microspheres, via consecutive processes of pickering mini-emulsion polymerization for core-shell formation, and calcination of the sacrificial core. The resulting hollow composite particles have mono-layered shells. The morphology and size characteristics of synthesized composite particles were investigated, using dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements.

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.593-601
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• 1987

A thermodynamic model to predict the stability of the water-in-oil type emulsion and the size of the droplets in stable emulsions was developed. Using this model, the effects of various factors government the droplet size in the metal salt solution-kerosene-span 80 system for the preparation of Al2O3-ZrO2 composite powders were investigated. It was shown that the given emulsion systems were thermodynamically unstable in every case but could be kinetically meta stable. When radius ofthe droplet was below nm, the increase in entropy change due to the configurational contribution of small droplets dominated the total free energy change for emulsification. The optimum conditions under which smaller deoplet was obtained were proposed and the validity of the model was proved with diameters of the droplet and composite powders experimentally determined.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.487-494
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• 1990

$Al_2O_3$-20w/o $ZrO_2$ composite powders were prepared by the emulsion-coprecipitation method and the effects of preparative conditions on powder characteristics were investigated. In the preparation of $Al_2O_3$-$ZrO_2$ composite powders, toluene was used instead of kerosene as the oil phase in emulsions. After coprecipitation, the emulsion was easily broken into a single liquid phase by adding methanol, and then precipitates could be effectively collected by filteration. The fact that all $ZrO_2$ phases present at room temperature in composite powders calcined at $1100^{\circ}C$ after washed by methanol had a tetragonal structure confirmed that methanol-washing enhanced the dispersibility of fine $ZrO_2$ particles in $Al_2O_3$ matrix. $Al_2O_3$-$ZrO_2$ composite powders were spherical particles of 0.2${\mu}{\textrm}{m}$ diameter. Pellets sintered at $1650^{\circ}C$ for 2hrs showed the relative theoretical density of 97.3% and the fracture toughness of 5.01MN/$m^{3/2}$.

• 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 Ceramic Society
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• v.25 no.3
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• pp.284-292
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• 1988

Alumina-zirconia composite powders for the purpose of improving fracture toughness and thermal shock resistance of alumina were prepared by the emulsion-kerosene drying method. The average particle size of composite powders was less then 1 $\mu\textrm{m}$ and their shapes were spherical. It was shown that the average particle size of composite powders decreased with the concentration of metal-salt in solution and the amount of span 80 added when preparing emulsions. The structure of all zirconia in composite powders heat-treated at 1200$^{\circ}C$ was a tetragonal form at room temperature. This result implied that fine zirconia particles were homogeneously dispersed in the alumina matrix.

• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.562-568
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• 2021

An O/W (oil in water) emulsion, wheat germ oil raw material, was produced by using natural wheat germ oil and composite sugar-ester. The effects of variables such as the hydrophile-lipophile balance (HLB) value, added emulsifier amount, and emulsification time on the average particle size, emulsification viscosity and ESI of O/W wheat germ oil emulsion were investigated. The parameters of the emulsification process produced by the central composite design model of the response surface methodology (CCD-RSM), which is a reaction surface analysis method, were simulated and optimized. The optimum process conditions obtained from this paper for the production of O/W wheat germ oil emulsion were 8.4, 6.4 wt%, 25.4 min for the HLB value, amount of emulsifier, and emulsion time, respectively. The predicted reaction values by CCD-RSM model under the optimum conditions were 206 nm, 8125 cP, and 98.2% for mean droplet size (MDS), viscosity, and ESI, respectively, based on the emulsion after 7 days. The MDS, viscosity and ESI of the emulsion obtained from actual experiments were 209 nm, 7974 cP and 98.7%, respectively. Therefore, it was possible to design an optimization process for evaluating the stability of the emulsion of wheat germ oil raw material by CCD-RSM.

• Elastomers and Composites
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• v.50 no.2
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• pp.110-118
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• 2015

In this study, diethylaminoethyl methacrylate-styrene-butadiene terpolymer (DEAEMA-SBR), in which diethylaminoethyl methacrylate (DEAEMA) was introduced to the SBR molecule as a third monomer, was synthesized by cold emulsion polymerization. It is expected that amine group introduced to a rubber molecule would improve dispersion of silica by the formation of hydrogen bond (or ionic coupling) between the amine group and silanol groups of silica surface. The chemical structure of DEAEMA-SBR was analyzed using proton nuclear magnetic resonance spectroscopy (H-NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Then, various properties of DEAEMA-SBR/silica composite such as crosslink density, bound rubber content, abrasion resistance, and mechanical properties were evaluated. As a result, bound rubber content and crosslink density of DEAEMA-SBR/silica compound were higher than those of the SBR 1721 composite. Abrasion resistance and moduli at 300% elongation of the DEAEMA-SBR/silica composite were better than those of SBR 1721 composite due to the high bound rubber content and crosslink density. These results are attributed to high affinity between DEAEMA-SBR and silica. The proposed study suggests that DEAEMA-SBR can help to improve mechanical properties and abrasion resistance of the tire tread part.