• Journal of Biomedical Engineering Research
• /
• v.11 no.1
• /
• pp.131-140
• /
• 1990

To improve antithrombogenicity of polymer that used in vascular graft and artificial organs, seeding of human endothelial cells on the polyurethane was studied. Human endothelial cells were ismlated from human umbilical veins, using type I collagenase, and identified with goat anti vWF antibodies. Human endothilial cell seeding was tried upon the polyurethane which has good mechanical property and resists stresses. The hydrophobic polyurethane surface was changed hydrophilic by corona discharf:e treatment. Surface hydrophilicity was measured with Wilhemly plate method and the goniometer. To evaluate matrix protein adsorption, fibronectin adsorption test was done. To eveluate cell adhesion, human endothelial cell attachment forces were measured rising a perfusion chamber of , ism diamter. Less cells were detached from the hydrophilically treated polyurethane. This showed that corona discharge on the polyurethane could improve matrix adsorption and endothelial cell attachment.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.197-198
• /
• 2009

고분자 전해질막으로 사용할 수 있는 소수성/친수성 랜덤 멀티블럭 공중합체를 합성하였다. 공중합체는 수산화기를 각 말단에 가지고 있는 소수성 올리고머, 친수성 올리고머 및 반응성이 좋은 커플링 단량체로 친핵성 치환 반응을 활용하여 합성 하였다. 높은 반응성의 커플링 단량체의 존재로 비교적 낮은 온도에서 합성이 됨으로서 고온에서의 에테르-에테르 교환반응에 의한 랜덤화를 억제할 수 있었으며, 높은 중합도의 공중합체를 합성 할 수 있었다. 각 수산화기로 같은 말단으로 조정된 올리고머는 투입 비율의 조정으로 쉽게 이온교환용량을 조정할 수 있었다. 솔루션 캐스팅 방법으로 강도를 가지고 잘 휘어지며 투명한 전해질막을 제조할 수 있었다. 전해질막은 이온전도도, 물흡수율, 부피 변화율, 연료 투과성 등의 측정이 되었다.

• Fibers and Polymers
• /
• v.6 no.2
• /
• pp.113-120
• /
• 2005

Helium-oxygen plasma treatments were conducted to modify poly(trimethylene terephthalate) (PIT) and poly(ethylene terephthalate) (PET) warp knitted fabrics under atmospheric pressure. Lubricant and contamination removals by plasma etching effect were examined by weight loss $(\%)$ measurements and scanning electron microscopy (SEM) analysis. Surface oxidation by plasma treatments was revealed by x-ray photoelectron spectroscopy (XPS) analyses, resulting in formation of hydrophilic groups and moisture regain $(\%)$ enhancement. Low-stress mechanical properties (evaluated by Kawabata evaluation system) and bulk properties (air permeability and bust strength) were enhanced by plasma treatment. Increasing interfiber and interyarn frictions might play important roles in enhancing surface property changes by plasma etching effect, and then changing low-stress mechanical properties and bulk properties for both fabrics.

• Elastomers and Composites
• /
• v.51 no.2
• /
• pp.128-137
• /
• 2016

The effect of the surface area of silicas on their reinforcing performance to styrene-butadiene rubber (SBR) compounds was systematically investigated. The feasibility of the Brunauer-Emmett-Teller surface area ($S_{BET}$) as a parameter representing the characteristics of the silicas was discussed compared to the mesopore volume, c value, oil absorption, and uptake of silane. The increase in $S_{BET}$ of silicas caused a considerable increase in Mooney viscosity, minimum torque, and hysteresis loss of the silica-filled SBR compounds, while significantly enhancing their abrasion property. These changes were explained by the attrition between the hydrophilic silica surface and the hydrophobic rubber chains. As expected, the change in $S_{BET}$ did not induce any remarkable changes in the cure, processing, tensile, and dynamic properties of the silica-filled SBR compounds because the crosslinking density of the rubber chains mainly determined these properties.

• Nuclear Engineering and Technology
• /
• v.43 no.3
• /
• pp.205-216
• /
• 2011

Recently, many research studies have investigated the enormous critical heat flux (CHF) enhancement caused by nanofluids during pool boiling and flow boiling. One of the main reasons for this enhancement is nanoparticle deposition on the heated surface. However, in real applications, nanofluids create many problems when used as working fluids because of sedimentation and aggregation. Therefore, artificial surfaces on silicon and metal have been developed to create an effect similar to that of nanoparticle deposition. These modified surfaces have proved capable of greatly increasing the CHF during pool boiling, and good results have also been observed during flow boiling. In this study, we demonstrate that the wetting ability of a surface, i.e., wettability, and the liquid spreading ability (hydrophilic surface property), are key parameters for increasing the CHF during both pool and flow boiling. We also demonstrate that when the fuel surface in nuclear power plants is modified in a similar manner, it has the same effect, producing a large CHF enhancement.

• Journal of the Korean Society of Industry Convergence
• /
• v.12 no.4
• /
• pp.193-202
• /
• 2009

In the preparation of anion charged asymmetric ultrafiltration membranes by the conventional phase inversion method, several variables could be adjusted to control membrane permeations. The anion charged materials and its original polymer have good solubility in N-methyl-2-pyrrolidone. The membranes having a hydrophilic property were less fouled the membrane prepared from the original polymer. The preparation conditions, operation conditions, and hydrophilicity of polymer have played an important role in determining the permeation properties of membranes.

• Journal of the Korean Chemical Society
• /
• v.64 no.6
• /
• pp.354-359
• /
• 2020

This research was conducted to analyze the compatibility of used monomers and produce the high functional contact lens material containing silicone monomers. Silicone monomer (Sil-OH), Trimethylsilylmethacrylate (TSMA) were used as additives for the basic combination of Polyhedral Oligomeric Silsesquioxane (POSS), methyl methacrylate (MMA) and methyl acrylate (MA). And also, the materials were copolymerized with ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent, AIBN (thermal polymerization initiator) as the initiator. It is judged that the fabricated lenses of all combinations are optically excellent and thus used monomers have good compatibility. Measurement of the optical and physical characteristics of the manufactured hydrophilic lens material were varied in each case. Especially TSMA with POSS increases the oxygen permeability and Sil-OH with POSS increases the wettability by the addition of Sil-OH. These materials were considered to have compatibility each other, so it can be used in functional contact lens material.

• Korean Journal of Ecology and Environment
• /
• v.34 no.1 s.93
• /
• pp.20-29
• /
• 2001

The amount, chemical composition and optical property of extracellular dissolved organic carbon (EOC) by phytoplankton were examined using axenic cultures of Microcystis aeruginosa, Anabaena flos-aquae, and Oscillatoria agardhii. The extracellular organic matter was categorized into five fractions (hydrophobic acids; AHSs, hydrophobic neutrals; HoNs, hydrophilic acids; HiAs, hydrophilic bases; HiBs, and hydrophilic neutrals; HiNs) using three adsorbent resins(XAD-8, cation, and anion). The release pattern and chemical composition of EOC varied with algal species and their growth phases. Percentage of extracellular release increased with age in all cultures. HiAs were the dominant component of EOC in all cultures, whereas the proportion of HiAs decreased with age in all cultures. In contrast, the proportions of HiBs and HiNs increased as cultures aged. In particular, the HiN fraction increased from 0% to 44% of EOC in M. aeruginosa and from 3.0% to 28% in A. flos-aquae, respectively. The proportion of AHSs was higher in the cultures of A. flos-aquae(7.5${\sim}$16%) and O. agardhii (8.7${\sim}$16%) than M. aeruginosa(0.2${\sim}$2.5%). The proportions of AHSs increased with culture age in M. aeruginosa and O. agardhii, but decreased in A. flos-aquae. The specific UV absorbance also varied among species; 1.9 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L$^{-1}$ for M. aeruginosa, 3.7 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L$^{-1}$ for A. flos-aquae, and 13.0 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L^{-1}$ for O. agardhii. The results of this study indicates that DOC excreted by three blue-green algae differed with species and the growth phase.

• Textile Coloration and Finishing
• /
• v.21 no.1
• /
• pp.38-45
• /
• 2009

First of all, the properties imparted to PET fabrics are resistance to and recovery from creasing or wrinkling when wet or dry; high resistance to stretch in the filament yarns but not in the staple; high abrasion resistance; good texture and appearance; resistance to heat ageing; good chemical resistance and good resistance, behind glass, to sunlight. But, the low moisture regain of PET fabric conduces to static troubles in textile processing. Furthermore, garments made from PET may, during wear, develop electric charges which attract to the fabric particles of soil(dirt, swarf, dust) flying in the air, so that the cuffs of shirts, for example, become soiled quickly and are not easily laundered clean. The sericin constitutes 25$\sim$30％ of silk protein and surrounds the fibroin fiber with sticky layer that supports the formation of a cocoon. The useful biochemical properties of sericin protein are oxidation resistant, antibacterial, UV resistant, hydrophilic property, and good affinity with hydrophobic material. These properties can be used as an improving reagent or a coating agent for natural and synthetic fibers, fabrics, and other intermediate products. The sericin is also applied to cross-link, and can be blended with other materials. In this study, we modified the surface of PET fabric by mixture of sericin finishing agent; sericin, polyuretane binder and 1,2,3,4-butanetetracarboxylic acid (BTCA) cross-link agent. Also, we investigated the finshing effect; moisture regain, stiffness, handle, drape and electrostatic. The moisture regain of PET fabric treated with sericin finishing agent was higher than that of untreated PET fabric. As a result of evaluating influence about handle of PET fabrics treated with sericin finishing agent, it was confirmed that the sericin finishing agent could be use as a linen like finishing agent.

• Macromolecular Research
• /
• v.13 no.5
• /
• pp.446-452
• /
• 2005

The interactions between the surface of scaffolds and specific cells play an important role in tissue engineering applications. Some cell adhesive ligand peptides including Arg-Gly-Asp (RGD) have been grafted into polymeric scaffolds to improve specific cell attachment. In order to make cell adhesive scaffolds for tissue regeneration, biodegradable nonporous poly(L-lactic acid) (PLLA) films were prepared by using a solvent casting technique with chloroform. The hydrophobic PLLA films were surface-modified by Argon plasma treatment and in situ direct acrylic acid (AA) grafting to get hydrophilic PLLA-g-PAA. The obtained carboxylic groups of PLLA-g-PAA were coupled with the amine groups of Gly-Arg-Asp-Gly (GRDG, control) and GRGD as a ligand peptide to get PLLA-g-GRDG and PLLA-g-GRGD, respectively. The surface properties of the modified PLLA films were examined by various surface analyses. The surface structures of the PLLA films were confirmed by ATR-FTIR and ESCA, whereas the immobilized amounts of the ligand peptides were 138-145 pmol/$cm^2$. The PLLA surfaces were more hydrophilic after AA and/or RGD grafting but their surface morphologies showed still relatively smoothness. Fibroblast adhesion to the PLLA surfaces was improved in the order of PLLA control