• 한국재료학회지
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• 제28권2호
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• pp.82-88
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• 2018

Stable slurries of YSZ in aqueous suspension with added polymer dispersants, namely, poly-methacrylic acid ammonium salt (PMMA), poly-acrylic acid (PAA) and poly-acrylic-co-maleic acid (PAMA), were mixed with the monomolecular dispersants citric acid and oxalic acid. The dispersion properties of the suspension were investigated using PSA, viscosity, sedimentation, and FT-IR. The polymer dispersants and monomolecular dispersants were attached to the YSZ surface by the carboxylic group, as shown by the FTIR results. A stabilized aqueous suspension was obtained when the polymer dispersant and citric acid were mixed and compared to the use of citric acid alone as a dispersant agent. When the polymer dispersant and citric acid were mixed and milled through attrition milling, there was a smaller particle size compared to when the polymer dispersant alone was used as a dispersant agent. This study determined that the particle size of the mixed dispersant was affected by the properties of the monomolecular dispersant and that the stability of the suspension was affected by the polymer dispersant. However, when slurries of YSZ were mixed with oxalic acid, the particle bridging behavior was the result of the high degree of viscosity and the small sedimentation height.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.23.2-23.2
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• 2010

Researches on the drying of particle/polymer suspensions receive attentions in technical applications such as manufacturing display and batteries. In this study, the effect of polymers on drying behavior of silica/poly(vinyl alcohol) suspension was investigated in terms of suspension stability and stress development during drying. The effect of polymer adsorption was studied by changing pH. More strongly flocculated suspension with lower pH became more dispersed and close-packed film after drying. Evaluation of potential energy allows us to suggest that the adsorbed polymers which bridge the particles introduce steric repulsion and lead flocculated suspension to dispersed film. When the effect of adsorption kinetics was studied by changing the mixing time, the adsorption amount, characteristic stress and dried film density showed a similar behavior in the form of with a single characteristic time. It implies that the drying process can be determined by simple characteristic equation with a single time constant.

• Korea-Australia Rheology Journal
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• 제15권4호
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• pp.179-185
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• 2003

Associating polymers act as flocculants in colloidal suspensions, because the hydrophobic groups (hydrophobes) can adsorb onto particle surfaces and create intermolecular cross-linking. The steady-shear viscosity and dynamic viscoelasticity were measured for suspensions flocculated by multichain bridging of associating polymers. The effects of surfactant on the suspension rheology are studied in relation to the bridging conformation. The surfactant molecule behaves as a displacer and the polymer chains are forced to desorb from the particle surfaces. The overall effect of surfactant is the reduction of suspension viscosity. However, the additions of a small amount of surfactant to suspensions, in which the degree of bridging is low, cause a viscosity increase, although the number of chains forming one bridge is decreased by the forced desorption of associating polymer. Since the polymer chains desorbed from one bridge can form another bridge between bare particles, the bridging density over the system is increased. Therefore, the surfactant adsorption leads to a viscosity increase. The surfactant influences the viscosity in two opposing ways depending on the degree of bridging.

• Korean Chemical Engineering Research
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• 제56권3호
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• pp.370-375
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• 2018

본 연구에서는 생리활성물질 (+)-dihydromyricetin의 입자크기 감소를 위하여 친수성 고분자 물질을 첨가하여 분별침전을 수행하였다. 고분자 물질(HPMC 2910, PVP K90, PVA)이 첨가된 분별침전을 통해 (+)-dihydromyricetin 입자크기를 감소시킬 수 있었다. 특히 분별침전 시 HPMC 2910 (0.1%, w/v)을 첨가할 경우, 대조군에 비하여 입자크기가 $38-68{\mu}m$ (32-40%) 정도 감소하여 입자크기 감소에 가장 효과적이었다. 또한 (+)-dihydromyricetin침전물의 입자크기는 친수성 고분자 물질 첨가에 따른 침전용액의 제타전위 절대값에 반비례함을 알 수 있었다.

• Macromolecular Research
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• 제10권4호
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• pp.215-220
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• 2002

The electrorheological (ER) and dielectric behaviors of the polypyrrole(PPy)-coated poly(ethyl methacrylate)(PEMA) suspensions in mineral oil were investigated. PPy was coated on PEMA particles to enhance the particle polarization, which would lead to the enhanced ER response. Various PPy-coated PEMA particles were synthesized by controlling the oxidant amount during the pyrrole polymerization, and the ER responses of their suspensions were investigated. The ER response initially increases with the oxidant amount, passes through a maximum, and then decreases with the oxidant amount. The initial increase in the ER response with oxidant amounts is due to the enhanced particle polarization with the increased particle surface conductivity. The dielectric properties of the corresponding suspensions support that the ER enhancement arises from the enhanced particle polarization. The decrease in the ER response at large oxidant amounts seems to arise from the increased conduction between the PPy-coated PEMA particles.

• 한국환경과학회지
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• 제13권9호
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• pp.799-806
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• 2004

The filtration tests were made in cell with a low concentrated suspension. The suspension with a concentration of $C_{M}$=1.14～2.67$\cdot$$10^{-3}$ g/g consists of paper paint and water. The particles in the suspension have a particle size x<1${\mu}m$. The used depth filters consists of glass fibres, which are coated by polymer. The filtration in depth filters accorded in different mechanism, which were explained by physical models. The model which would be allows to make a promise of the filtration reaction. This filter media allows to get a high filtration time and a good separation rate. The Particle distribution is measured by a photon correlation spectroscopy(PCS). PCS measures particle sizes 0.03 ${\mu}m$${\mu}m$ in the suspension. The filtered suspension has a very low concentration Co{\le}5{\times}10_{-4}$ g/g of solid in sample. The PCS also informs us about the number of the particles in the suspension. The makes it possible to calculate the concentration of the in sample.

• 폴리머
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• 제28권1호
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• pp.18-23
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• 2004

역상 현탁중합법을 이용하여 폴리(아크릴산 포타슘-co-아크릴아마이드) 고흡수성 수지를 입자형태로 제조하였다. 제조된 고분자의 평균 입자 지름은 50～300 $\mu\textrm{m}$ 범위 내에서 계면활성제의 양이 증가함에 따라 감소하였다. 중량측정법을 이용하여 흡수 및 증발 과정에서의 동적, 평형 팽윤 특성을 살펴보았다. 수용액 내에서의 흡수에 따른 입자의 팽윤도는 가교밀도뿐만 아니라 입자의 크기, 외부수용액의 염 농도, 공중합체 조성 등에 크게 영향을 받는 것으로 나타났다. 입자 크기, 첨가된 가교제의 농도, 그리고 외부의 이온농도가 감소함에 따라 흡수되는 물의 양이 증가하였다. 수분증발거동은 흡수거동과는 달리 입자의 크기나 공중합체의 조성, 가교제 양 등에 많은 영향을 받지 않았다.

• 폴리머
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• 제27권5호
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• pp.493-501
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• 2003

의치상 레진 (틀니)의 기본 물질로 사용되는 폴리(메틸 메타아크릴레이트) (PMMA) 입자를 폴리(비닐 알코올) (PVAL)을 안정제로 사용하여 현탁중합법으로 중합하였고, PVAL 농도와 교반속도, 공단량체의 도입에 따른 PMMA의 입자 크기 변화 및 분자량의 변화를 관찰하였다. 또한 합성된 PMMA 수지와 메틸 메타아크릴레이트 단량체를 이용하여 고체/액체 비 (P/L ratio)를 2:1 로 하여 병상물을 제조하고, 일정한 가압성형 조건하에서 제작된 시편으로 수지의 입자 크기 및 분자량에 따른 PMMA에 기초한 틀니용 수지의 기계적 물성 변화를 관찰하였다. 그 결과 평균입자 크기가 100 $\mu$m 이하에서는 분자량이 커질수록 기계적 물성이 높게 나타났으며, 그 이상인 영역에서는 분자량에 상관없이 입자 크기가 증가할수록 기계적 물성의 저하 현상이 관찰되었다. 아울러 중합시 교반속도와 PVAL의 농도를 조절하여 크기와 분자량을 조절 가능하였는데, P/L 부피비가 2인 조건에서 제조된 열경화성 틀니용 수지로 이용되는 입자의 평균크기는 100 $\mu$m 정도가 적절하며, 분자량은 3.0${\times}$$10^{5}$ 전후가 적절함을 알 수 있었다.다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2009년도 추계학술발표회 논문집
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• pp.79-84
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• 2009

Understanding the polymer adsorption in particle/binder/solvent system is important to achieve successful film products. While most of the reported work has dealt with the suspension microstructure, a few studies have focused on film formation. We investigated the effect of adsorption on film formation through measurement of adsorption amount in suspension and stress development in drying film with respect to mixing time ($t_m$). All of the adsorption amount (PVA), characteristic stress ($\sigma_{ch}$) exhibited similarities expressed by the form of $1-e^{t_m/{\tau}}$. The porous and non-unifonn dried film at short tm became close-packed and uniform with longer $t_m$. We found that polymer adsorption plays the key role in film fonnation as it introduces steric repulsion in suspension and suppresses the flocculation during solvent evaporation. We also found that the mixing time for the saturated polymer adsorption is the important variable to acquire the consolidated and uniform film microstructure.

• 한국자기학회지
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• 제5권5호
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• pp.667-671
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• 1995

The viscometric technique is used to study the effects of microstructure on the viscosity (viscosity vs. concentration or shear rate) of magnetic particle suspensions. In this characterization, measurement of suspension viscosity is used to obtain the dependence of viscous energy dissipation on microstructural state of dispersions. Microstructural shape effects which are related to particle orientation are then indirectly obtained. Empirical formulas from mean field theory and the Mooney equation, which are applicable at high concentration of magnetic particles, are used to relate viscosity to particle concentration. The validity and physical meaning of these equations are discussed.