• 한국산학기술학회논문지
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• 제19권6호
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• pp.147-153
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• 2018

이중유화법을 통하여 BSA 수용액을 봉입하는 PLGA 마이크로캡슐 입자를 제조하였다. 마이크로캡슐 입자 외부의 수용액 상에서는 입자 표면의 경화를 위하여 유화제를 금속염으로 대체하였다. 제조한 마이크로캡슐 입자에 대하여서 모폴로지, 입자직경 BSA 봉입효율 및 in-vitro 방출실험을 수행하였다. 전자현미경(SEM) 촬영을 통하여 마이크로캡슐 입자는 매끄러운 표면의 특성을 지녔으며 $1-7{\mu}m$ 범위의 직경을 갖는 것이 확인되었다. 마이크로캡슐 입자의 모폴로지는 주로 일차 유화액 내 내부 수용액 대비 고분자 용액의 부피 비 그리고 입자 외부 수용액에서의 금속염의 농도에 직접적인 영향을 받았다. 또한 이러한 요소는 단백질 봉입효율과 in-vitro 방출에도 일부 영향을 미쳤다. 본 실험에서 제조한 마이크로캡슐 입자는 in-vitro 방출 실험에서 초기에 높은 유속의 방출 현상을 보였다. 그렇지만 본 연구에서 제조한 마이크로캡슐 입자는 다른 연구의 결과에 비해 긴 기간 동안의 방출을 보였다. 이상의 결과를 통해 2가의 금속염이 마이크로캡슐 입자의 제조에서 유화제를 대체할 수 있는 좋은 방편이 될 수 있다는 결론을 내릴 수 있었다.

• Membrane and Water Treatment
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• 제7권2호
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• pp.101-113
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• 2016

In this study, to improve the water flux of porous hydrophobic membranes, various water-soluble polymers including neutral, cationic and anionic polymers were adsorbed using 'salting-out' method. The adsorbed hydrophobic membrane surfaces were characterized mainly via the measurements of contact angles and scanning electron microscopy (SEM) images. To enhance the durability of the modified membranes, the water-soluble polymers such poly(vinyl alcohol) (PVA) were crosslinked with glutaraldehyde (GA) and found to be resistant for more than 2 months in vigorously stirred water. The water flux was much more increased when the ionic polymers used as the coating materials rather than the neutral polymer and in this case, about 70% of $0.31L/m^2{\cdot}h$ (LMH) to 0.50 LMH was increased when 300 mg/L of polyacrylamide (PAAm) was used as the coating agents. Among the cationic coating polymers such as poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA), poly(acrylic acid-comaleic acid) (PAM) and poly(acrylic acid) (PAA), PSSA_MA was found to be the best in terms of contact angle and water flux. In the case of PSSA_MA, the water flux was enhanced about 80%. The low concentration of the coating solution was better to hydrophilize while the high concentration inclined to block the pores on the membrane surfaces. The best coating condition was found: (1) coating concentration 150 to 300 mg/L, (2) ionic strength 0.15, (3) coating time 20 min.

• 대한치과보철학회지
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• 제35권1호
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• pp.221-243
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• 1997

The objective of this study was to characterize the mechanical properties of $Y_{2}O_{3}$-containing glass infiltrated ceramic core material, which was made by pressureless powder packing method. A pure alumina powder with a grain size of about $4{\mu}m$ was packed without pressure is silicon mold to form a bar shaped sample, and applied PVA solution as a binder. Samples were sinterd at $1350^{\circ}C$ for 1 hour. After cooling, $Y_{2}O_{3}$-containing glass($SiO_{2},\;Y_{2}O_{3},\;B_{2}O_{3},\;Al_{2}O_{3}$, ect) was infiltrated to the sinterd samples at $1300^{\circ}C$ for 2 hours and cooled. Six different proportions $Y_{2}O_{3}$ of were used to know the effect of the mismatch of the thermal expansion coefficient between alumina powder and glass. The samples were ground to $3{\times}3{\times}30$ mm size and polished with $1{\mu}m$ diamond paste. Flexural strength, fracture toughness, hardness and other physical properties were obtained, and the fractured surface was examined with SEM and EPMA. Ten samples of each group were tested and compared with In-Ceram(tm) core materials of same size made in dental laboratory. The results were as follows : 1. The flexural strengths of group 1 and 3 were significantly not different with that of In-Ceram, but other experimental groups were lower than In-Ceram. 2. The shrinkage rate of samples was 0.42% after first firing, and 0.45% after glass infiltration. Total shrinkage rate was 0.87%. 3. After first firing, porosity rate of experimental groups was 50%, compared with 22.25% of In-Ceram. After glass infiltration, porosity rate of experimental groups was 2%, and 1% in In-Ceram. 4. There was no statistical difference in hardness between two materials tested, but in fracture toughness, group 2 and 3 were higher than In-Ceram. 5. The thermal expansion coefficients of experimental groups were varied to $4.51-5.35{\times}10^{-6}/^{\circ}C$ according to glass composition, also the flexural strengths of samples were varied. 6. In a view of SEM, many microparticles about $0.5{\mu}m$ diameter and $4{\mu}m$ diameter were observed in In-Ceram. But in experimental group, the size of most particles was about $4{\mu}m$, and a little microparticles was observed. The results obtained in this study showed that the mismatch of the thermal expansion coefficients between alumina powder and infiltrated glass affect the flexural strength of alumin/glass composite. The $Y_{2}O_{3}$-containing glass infiltrated ceramic core made by powder packing method will takes less time and cost with sufficient flexural strength similar to all ceramic crown made with slip casting technique.