• 한국건설순환자원학회논문집
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• 제9권2호
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• pp.127-134
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• 2021

PMHS와 PVA를 혼합한 소수성 유액을 시멘트 모르타르에 혼입하여 수화생성물과 미세구조의 변화를 관찰하고, 압축강도와 휨강도를 실험적으로 평가하고자 하였다. 소수성 유액은 메타카올린과 PVA 섬유를 추가하고 교반속도와 순서를 조정하여 쉘형태의 유액을 제조하였으며, 모르타르배합시 혼입하여 내부 공극의 충진과 수화생성물의 변화를 도모하고자 하였다. 소수성 유액이 혼입된 모르타르는 미세공극이 충진되고 수화생성물표면이 유액에 의해 도막이 생성되는 것이 관찰되었다. OPC와 비교하여 유액이 혼입된 모르타르의 전체 기공면적과 기공률이 감소하는 것으로 분석되었으며, 일부 변수에서 기공지름의 중간값의 감소가 나타났다. 유액을 1% 혼입한 경우에 압축강도의 증가가 나타났으며, 2% 혼입시에는 강도의 감소가 발생하였다.

• 접착 및 계면
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• 제3권1호
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• pp.13-19
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• 2002

We have studied on the surface and adhesion properties for acrylic terpolymers, having both hydrophobic and hydrophilic side chains, synthesized via solution polymerization. In order to develop a waterborne material. we tried to synthesize these terpolymers via emulsion polymerization. The polymeric emulsion synthesized was mainly composed of methyl methacrylate (MMA), methoxy-polyethyleneglycol methacrylate (MPEGMA) having hydrophilic side chains and methoxypolypropyleneglycol methacrylate (MPEGMA) having hydrophobic side chains. The viscosities of this series increased with an increase in the content of the co-monomer such as MPEGMA and (MPEGMA). This behavior resulted in the increase in the diameter and heterogeneity of the emulsion particle via AFM observation. Furthermore. the tensile adhesion strength and 90-degree peel strength of the adhesive of these polymeric emulsions were measured. In the case of polymeric emulsion composed of the same content of both hydrophilic and hydrophobic component, the adhesion property showed the highest value. However, since the adhesion properties as a practical applicable adhesive were poor, some improvements were required. When the composition above was modified with butyl acrylate (BA), the improvement effect on adhesion strength was accepted. In particular, 90-degree peel strength increased up to a maximum of 400% of the original value.

• 공업화학
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• 제8권1호
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• pp.29-38
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• 1997

고농축에멀션중합방법을 이용하여 친수성-친유성 고분자복합소재를 합성하였다. w/o 형태의 고농축에멀션의 연속상은 styrene이며, 분산상은 수용성 acrylamide용액으로 분산상의 부피분율이 0.74 이상이다. 중합온도에서 에멀션의 안정성에 미치는 주요 요인들로는 친유성액체와 친수성액체의 물리화학적 특성인 극성, pH, 이온세기 및 계면활성제의 종류와 농도가 있다. 친유성액체와 친수성액체 사이의 계면장력이나 친수성액체와 계면활성제 수용액사이의 계면장력에 있어 계면장력의 값이 큰 경우는 높은 에멀션의 안정성을 나타낸다. 계면활성제의 HLB가 3.0~9.0 경우와 계면활성제의 농도가 CMC가 이상에서 에멀션이 높은 안정성을 나타낸다. 전자현미경을 이용한 조사에 의하며 복합재료는 분산상의 Poly acrylamide입자가 망상구조의 얇은 polystyrene필림에 의해 분리된 구조로 이루어져 있음을 보여주고 있다. 고농축에멀션에서부터합성된 고분자복합재료막은 물-에탄온 혼합물에서 물에 대해서 높은 선택성을 나타내었으며, 또 에탄올의 농도가 증가할수록 막의 선택도는 증가하였으나 투과속도는 감소함을 나타내었다.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.424-431
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• 2009

Treatment for water repellency on the carbon supports of GDL which composed a part of MEA has been suggested as a solution to prevent flooding. PTFE is a fluoropolymer that has hydrophobic property and a PTFE emulsion was selected as waterproof agent in this investigation. Carbon paper was coated by PTFE emulsion with different particle size of 5~500 nm and 3~$5\;{\mu}m$ as various concentration. PTFE coated carbon paper has difference in weight variation changed proportionally at PTFE concentration and coating times. Then gas permeability of the coated carbon paper with emulsion of 3~$5\;{\mu}m$ PTFE was changed vastly. Characteristics of carbon paper coated with different PTFE emulsion were analyzed by FE-SEM, FT-IR spcetroscopy and were evaluated by weight variations, gas permeability and water contact angle.

• 한국구조물진단유지관리공학회 논문집
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• 제25권1호
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• pp.25-32
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• 2021

고내구성 친환경 콘크리트를 개발하기 위하여 폴리메틸 하이드로실록산과 폴리비닐알코올을 교반, 혼합하여 발수 및 소수성화합물을 제조하였다. 시멘트페이스트에 혼합물을 첨가한 후 BSE와 EDS 분석을 통하여 수화반응 특성과 화학조성의 변화 정도를 분석하였으며, MIP 분석에 의해 미세공극을 평가하였다. PMHS 유액을 혼입한 시멘트는 수화반응성이 높아지고 모세공극률이 낮아지는 것으로 분석되었으나, 시멘트 페이스트내에서의 유액의 분산 정도에 따라 공극률의 편차가 발생하는 것으로 나타났다. 메타카올린을 혼입한 유액의 경우에는 PMHS 유액만을 사용한 경우와 수화도와 공극률에서 거의 차이가 없는 것으로 나타났다. 그러나 시멘트 표면을 PMHS 유액으로 도포한 경우의 접촉각은 OPC와 비교하여 크게 증가하는 것으로 나타났으며, 특히 PVA 섬유를 같이 사용한 경우에는 과소수성 표면으로 변화되는 것으로 분석되었다.

• Macromolecular Research
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• 제11권3호
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• pp.198-201
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• 2003

Aqueous emulsion of polyurethane (PU) ionomers were reinforced with hydrophobic nanosilica to give composites. The aqueous emulsion was stable and the particle size increased as the content of hydrophobic nanosilica was increased. The reinforcing effect of nanosilica in mechanical properties of these composites were examined by dynamic mechanical and tensile tests, and the Shore A hardness was measured. Enhanced thermal and water resistance and marginal reduction in transparency of these composites were observed compared with pristine polymer. These results were similar with those of our previous studies on waterborne PU/organoclay nanocomposites.

• 한국식품영양과학회지
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• 제37권11호
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• pp.1465-1471
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• 2008

지용성의 토코페롤이 갖고 있는 많은 생리활성 기능을 수용액 상태에서도 발현할 수 있도록 유지 용해성을 갖는 토코페롤을 친수성 및 친유성 계면활성제를 이용하여 수분산 기법으로 최적의 토코페롤 유화액을 제조하고 최적의 유화 critical micellization concentration(CMC)을 선정하고자 표면장력 및 유화액의 저장안정성을 측정하였다. 실험에 사용한 토코페롤의 분자량은 $340{\sim}360$ 정도였으며 유화모델은 O/O/W/W형으로 선정하였다. 유화안정성과 표면장력과의 상관관계를 살펴보면, 유화액의 표면장력이 $40{\sim}46\;dyne/cm$에서 안정성을 확인할 수 있었으며, 표면장력이 40 dyne/cm이하로 떨어졌을 경우에는 유화안정성이 낮아졌다. 토코페롤의 유화안정성 실험 결과, 20%, 30%, 40% 수용성 토코페롤 유화액 모두에서 hydrophobic 계통의 유화제로 polyglycerine polyricinoleate를 적용한 유화 에멀젼에서 유화안 정성이 높았으며, hydrophilic 계통의 유화제에서는 polyglycerine monostearate> polyglycerine monooleate> polyoxyethylene(20) sorbitan monooleate$\geq$ polyoxyethylene(20) sorbitan monolaurate 순으로 유화안정성을 나타내었다.

• 한국응용과학기술학회지
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• 제23권1호
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• pp.1-11
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• 2006

The W/O emulsion was formed by mixing hydrophobic nonion surfactants of span 80 and tween 60 with kerosine, and by adding sodium silicate aqueous solution. Precipitating the W/O emulsion by sodium bicarbonate resulted in spherical silica particles. Shape and size distribution of silica particles were observed. The particles were spherical and they have narrow size distribution. Particle sizes were 9.29, 7.39 and $5.73\;{\mu}m$ at homogenizer speed of 2500, 3000, and 3500 rpm, respectively. The particle size was decreased by increasing agitation speed due to the formation of emulsion droplet. At fixed agitation speed, absorbed paraffin oil weight were measured and the $SiO_2/Na_2O$ mole ratio effects on particle size were investigated. Particle size was decreased by increasing the mole ratio of $SiO_2/Na_2O$.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.145-148
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• 2012

Spherical silica aerogel powders were fabricated via an emulsion polymerization method from a water glass. A water-in-oil emulsion, in which droplets of a silicic acid solution are emulsified with span 80 (surfactant) in n-hexane, was produced by a high power homogenizer. After gelation, the surface of the spherical silica hydrogels was modified using a TMCS (trimethylchlorosilane)/n-hexane solution followed by solvent exchange from water to n-hexane. Hydrophobic silica wet gel droplets were dried at 80 ℃ under ambient pressure. A perfect spherical silica aerogel powder between1 to 12 ㎛ in diameter was obtained and its size can be controlled by mixing speed. The tapping density, pore volume, and BET surface area of the silica aerogel powder were approximately 0.08 g·cm-3, 3.5 ㎤·g-1 and 742 ㎡·g-1, respectively.

• Macromolecular Research
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• 제9권1호
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• pp.51-65
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• 2001

Two-stage emulsion polymerizations of hydrophobic monomers on hydrophilic seed polymer particles were carried out to make core-shell composite particles. It was found that the loci of polymerization in the second stage were the surface layer of the hydrophilic seed latex particles, and that it has resulted in the formation of either eccentric core-shell particles with the core exposed to the aqueous phase or aggregated nonspherical composite particles with the shell attached on the seed surface as many small separated particles. The driving force of these phenomena is related to the gain in free energy of the system in going from the hydrophobic polymer-water interface to hydrophilic polymer-water interface. Thermodynamic analysis of the present polymerization system, which was based on spreading coefficients, supported the likely occurrence of such nonspherical particles due to the combined effects of interfacial free energies and phase separation between the two polymer phases. A hypothetical pathway was proposed to prepare hydrophilic core-hydrophobic shell composite latex particles, which is based on the concept of opposing driving and resistance forces for the phase migration. It was found that the viscosity of the monomer-swollen polymer phase played important role in the formation of particle morphology.