• Archives of Plastic Surgery
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• 제33권4호
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• pp.413-422
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• 2006

Purpose: This study was designed to compare the wound healing effect of silk fibroin, alginate and fibroin/ alginate blend sponge with clinically used Nu gauze in a rat skin defect model. Methods: Two full thickness excisions were made on the back of Sprague-Dawley rat. The excised wound was covered with either of the silk fibroin(SF), alginate (SA), or fibroin/alginate blend sponge(SF/SA). On the postoperative days of 3, 7, 10 and 14, the wound area was calculated by image analysis software. At the same time, a skin wound tissue was biopsied. Results: Healing time 50% ($HT_{50}$) of SF/SA sponge treated group was dramatically reduced as compared with that of control treatment. We also found that the $HT_{50}$ of SF/SA sponge was significantly decreased as compared with either those of SF or SA treatment. Furthermore, SF/SA treatment significantly increased the size of epithelialization and collagen deposition as well as the number of PCNA positive cells on epidermal basement membrane as comapred with those of control treatment. Conclusion: Our results suggest that the wound healing effect of SF/SA blend sponge is the best among other treatments including SF and SA during the whole wound healing period.

• 폴리머
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• 제32권6호
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• pp.593-597
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• 2008

배기가스에 포함된 이산화탄소를 분리하기 위해 polystyrene-block-polybutadiene(SB) 이종 블록 공중합체와 폴리페닐렌 옥사이드(PPO) 블렌드로부터 기체 분리막을 제조하였다. SB/PPO 블렌드에서 폴리스티렌 블록과 PPO는 실험 범위내에서 단상의 블렌드를 형성하였다. SB/PPO 블렌드에서 PPO 함량이 증가하여 40$\sim$50wt% 범위에서 플리부타디엔 블록은 연속상에서 불연속상으로 플리스티렌 블록과 PPO로 구성된 상은 불연속상에서 연속상으로 전이가 나타났다. 전이가 관찰되는 블렌드 조성에서 급격한 기체 투과도 감소와 선택도 증가가 관찰되었다. 또 블렌드가 50 wt% 이상의 PPO를 포함할 경우 기계적 강도가 확보되어 실험한 최대 압력인 약 10기압까지 변형없이 우수한 투과도와 선택도를 갖는 기체 분리막 제조가 가능하였다.

• 멤브레인
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• 제23권6호
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• pp.460-468
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• 2013

가압식 MF공정의 전처리공정으로 침전지가 없는 혼화/응집공정에서 적정응집제 투입농도선정 및 유기물 제거성능을 평가하였다. 전처리 공정에서 생성된 플럭이 가압펌프의 임펠러에 의해 해체됨을 확인하였으며 원수탁도가 10 NTU 이하로 유입이 될 때, 혼화/응집조와 펌프후단에서 플럭형성을 위한 최적응집제 투입량은 4 mg/L (as PACl 17%)이었다. 이때의 DOC 제거율은 평균 43%이었으며, 응집제투입량을 계속적으로 증가시켜 8 mg/L (as PACl 17%)로 투입을 하였을 때, DOC 제거율은 평균 48%를 나타내어 제거율은 크게 개선되지 않았다. 전처리가 없는 PVDF 가압식 MF공정의 TMP는 0.54 bar에서 운영이 되었으며, 혼화/응집 전처리 공정을 적용하여 운영 시 TMP는 0.41 bar로 안정적인 운영이 가능하였다.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.151-160
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• 2014

CL-SPEEK/Cs-TPA/$CeO_2$ composite membrane was prepared for polymer electrolyte membrane water electrolysis (PEMWE). In order to improve the electrochemical, mechanical, durabilities and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated and the organic-inorganic blend composite membranes was prepared by loading cesium-substituted tungstophosphoric acid (Cs-TPA) by titration method with cross-linking agent contents of 0.01mL. Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the PEMWE circumstance and to increase the duration of the membrane. CL-SPEEK/$Cs_{(1)}$-TPA/CeriaIn conclusion, 1% membrane showed the optimum results such as 0.119 S/cm at $80^{\circ}C$ of proton conductivity and 62MPa of tensile strength.

• Macromolecular Research
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• 제16권6호
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• pp.549-554
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• 2008

Proton conducting crosslinked membranes were prepared using polymer blends of polystyrene-b-poly(hydroxyethyl acrylate)-b-poly(styrene sulfonic acid) (PS-b-PHEA-b-PSSA) and poly(vinyl alcohol) (PVA). PS-b-PHEA-b-PSSA triblock copolymer at 28:21:51 wt% was synthesized sequentially using atom transfer radical polymerization (ATRP). FT-IR spectroscopy showed that after thermal ($120^{\circ}C$, 2 h) and chemical (sulfosuccinic acid, SA) treatments of the membranes, the middle PHEA block of the triblock copolymer was crosslinked with PVA through an esterification reaction between the -OH group of the membrane and the -COOH group of SA. The ion exchange capacity (IEC) decreased from 1.56 to 0.61 meq/g with increasing amount of PVA. Therefore, the proton conductivity at room temperature decreased from 0.044 to 0.018 S/cm. However, the introduction of PVA resulted in a decrease in water uptake from 87.0 to 44.3%, providing good mechanical properties applicable to the membrane electrode assembly (MEA) of fuel cells. Transmission electron microscopy (TEM) showed that the membrane was microphase-separated with a nanometer range with good connectivity of the $SO_3H$ ionic aggregates. The power density of a single $H_2/O_2$ fuel cell system using the membrane with 50 wt% PVA was $230\;mW/cm^2$ at $70^{\circ}C$ with a relative humidity of 100%. Thermogravimetric analysis (TGA) also showed a decrease in the thermal stability of the membranes with increasing PVA concentration.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권6호
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• pp.426-432
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• 2001

Perstractive fermentation is a good way to increase the productivity of bioreactors. Us-ing Propionibacteria as the model system, the feasibility of using supported emulsion liquid mem-brane(SELM) fro perstractive fermentation is assessed in this study. Five industrial solvents were considered as the solvent for perparing the SELM. The more polar a solvent, is the higher the par-tition coefficeint However, toxicity of a solvent also increases with its polarity. CO-1055(indus-trial decanol/octanol blend)has the highest partition coefficient toward propionic acid among the solvents that has no molecular toxicity toward Propionibacteria, A preliminary extraction study was conducted using tetradecane as solvent in a hydrophobic hollow fiber contactor. The results confirmed that SELM eliminates the equilibrium limitation of conventional liquid-liquid extrac-tion and allows the use of a non-toxic solvent with low partition coefficient.

• Macromolecular Research
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• 제15권5호
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• pp.459-464
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• 2007

Polymer electrolyte membranes, featuring ionic channels, were prepared from sulfonated dextran/ poly(vinyl alcohol) (sD/PVA) membranes. A stiff sulfated dextran was chosen as the route for ionic transport, since ionic sites are located along the stiff dextran main chain. The sD/PVA blend membranes were annealed and then chemically crosslinked. The characteristics of the crosslinked sD/PVA membranes were investigated to determine their suitability as proton exchange membranes. The proton conductivity was found to increase with increasing amounts of sD inside the membrane, which reached a maximum and then decreased when the sD content exceeded 30 wt%, while the methanol permeability increased with increasing sD content. The good dispersion of sD inside the membrane, which serves as an ionic channels mimic, played a significant role in proton transportation.

• 한국염색가공학회지
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• 제35권4호
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• pp.231-238
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• 2023

Microporous gel films of 29 m were prepared by the gel drawing of UHMWPE/soybean oil blend (4:6, w/w) up to 800%. The stretched films containing the optimal photoinitiator concentration, depending on the film thickness, was cross-linked under 365 nm LED-UV irradiation and the oil was extracted with n-hexane, resulting in a gel fraction of 95 % or more. With the formation of the cross-linked structure, the melt-down temperature and melt-down elongation increased by 16 ℃ and by 63% respectively. Also the thermal stability of the crosslinked UHMWPE was proved by the area shrinkage under the heat treatment decreased to 3.8 % compared to 17.4 % for the pristine film, and by the reductions in the combustion heat. The enhanced thermal stability of the crosslinked UHMWPE microporous membranes can be used for various industrial applications such as filters, electric vehicles and energy storage systems.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.175-176
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• 2003

Generally, The protone exchange membrane (PEM) contains cationic exchange groups such as SO3$\^$-/ group. The poly(styrene sulfonic acid) (PSSA) and its copolymers are widely studied because of easily synthetic method and higher conductivities. However, PSSA is not used individually because of poor physical properties such as brittleness and relatively lower Tg. So some researchers are concerned engineering plastics (EP) such as polyimides, polysulfone, polyketones, and poly(2,6-dimethyl-1,4-phenylene oxide) (MPPO) etc. (omitted)

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.103-110
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• 2005

Proton conducting solid polymer electrolyte (SPE) membranes have been used in many energy technological applications such as water electolysis, fuel cells, redox-flow battery, and other electrochemical devices. The availability of stable membranes with good electrochemical characteristics as proton conductivity at high temperatures above 80 $^{\circ}C$ and low cost are very important for its applications. However, the presently available perfluorinated ionomers are not applicable because of high manufacturing cost and high temperature use to the decrease in the proton conductivity and mechanical strength. In order to make up for the weak points, the block copolymer (BPSf) of polysulfone and poly (phenylene sulfide sulfone) were synthesized and sulfonated. The electrolyte membranes were prepared with phosphotungstic acid (HPA)/sulfonated BPSf via solution blending. This study would be desirable to investigate the interaction between the HPA and sulfonated polysulfone. The results showed that the characteristics of SPSf/HPA blend membrane was a better than Nafion at high temperature, 100 $^{\circ}C$. These membranes proved to have a high proton conductivity, $6.29{\times}10-2$ S/cm, a water content, 23.9%, and a ion exchange capacity, 1.97 meq./g dry membrane. Moreover, some of the membranes kept their high thermal and mechanical stability.