• Journal of Pharmaceutical Investigation
• /
• v.28 no.1
• /
• pp.1-5
• /
• 1998

The effect of synthetic polymer membranes on the permeation rate of dideoxynucleoside-type anti-HIV drugs through hairless rat skin was studied using ethylene/vinyl acetate copolymer (EVA) and ethylene/methyl acrylate copolymer (EMA) membranes fabricated by solvent casting method. In vitro skin permeation kinetics study of DDC (2',3'-dideoxythymidine), DDI (2',3'-dideoxyinosine) and AZT (3'-azido-3'-deoxythymidine) across the (membrane/skin) composite was conducted for 24 hours at $37^{\circ}C$ using the Valia-Chien skin permeation system. The results showed that skin permeation rate of each drug across the (skin/membrane) composite was mainly dependent on the property of the membrane. Proper selection of the polymeric membrane which resembles hydrophilicity/lipophilicity of the delivering drug was important in controlling the skin permeation rate.

• Polymer(Korea)
• /
• v.29 no.1
• /
• pp.19-24
• /
• 2005

Polymer blends containing polypropylene (PP) with compatibilizers were prepared using twin screw extruder. Physical properties were investigated using universal test machine (UTM) and Izod impact tester. In the PP/acrylonitrilebutadiene-styrene (ABS) blends, mechanical strength was increased with the addition of PP-g-styrene acryloritrile (PP-g-SAN) compatibilizer, and the ductility was increased with the addition of ethylene-ethyl acrylate-maleic anhydride (E-EAMAH-g-SAN) compatibilizer. For the PP/ABS/ polycarbonate (PC)/Nylon-6,6 blends, impact strength was increased with the addition of ethylene glycidylmethacrylate (E-GMA compatibilizer) up to 0.5 phr. In the case of the PP/ABS/PC/Nylon-6,6/poly(methyl methacrylate) (PMMA)/poly(oxymethylene) (POM)/poly(vinyl acetate) (PVC)/poly(butylene terephthalate) (PBT) blends, mechanical properties were increased by the complex compatibilizing effects of PP-g-SAN, E-EA-MAH-g-SAN and E-GMA, respectively.

• Fashion & Textile Research Journal
• /
• v.10 no.3
• /
• pp.371-376
• /
• 2008

Poly(ethylene-co-vinylacetate) (EVA) microspheres were prepared by thermally induced phase separation (TIPS) in toluene. The microsphere formation occurred by the nucleation and growth mechanism in metastable region. The effects of the concentration and component of the polymer and cooling rate on microsphere formation were investigated. The microsphere formation and growth were followed by the cloud point of the optical microscope measurement. The microsphere size distribution, which was obtained by particle size analyzer, became broader when the polymer concentration was higher, the content of vinyl acetate in EVA copolymer was higher, the cooling rate of EVA copolymer solution were lower. The content of disperse dye in EVA microsphere was obtained by TGA thermal analysis, the dye content of EVA15 and EVA18 were 3.5 and 2.0 wt% respectively.

• Journal of Radiation Industry
• /
• v.4 no.1
• /
• pp.73-77
• /
• 2010

In recent day, there is much interest in the biocidal activity of silver since silver is known to be safe and effective as disinifectant and biocidal material against coliforms and viruses. In this study, hydrogels containing silver acetate as antibacterial agent have been prepared using gamma rays irradiation. The hydrogels are composed of poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG), carrageenan and silver acetate. The concentration of solution was 9 wt%. The ratio of PVP : PEG : carrageenan was 6 : 1 : 2. The concentration of the silver acetate were 0, 0.01, 0.03, 0.05 and 0.07% and Gamma irradiation dose was 25 kGy. The Gamma irradiation dose in hydrogels with 0.01% silver acetate were 20 kGy, 35 kGy, 50 kGy, 65 kGy, and 80 kGy. The results showed that 0.01% silver acetate concentration of hydrogels by 25 kGy irradiation dose showed the highest antibacterial activity against E. coli and Staphylococcus aureus. Moreover, antibacterial activity of various Gamma irradiation dose in hydrogels treated 0.01% silver acetate showed highest 35 kGy irradiation dose against Staphylococcus aureus.

• Applied Biological Chemistry
• /
• v.11
• /
• pp.67-76
• /
• 1969

The reduced pressure storage of apple, American Summer Pairman, was investigated comparing with the other storage methods and the following results were obtained. 1. The reduced pressure storage was better to extend the storage life and freshness of apples than the controlled atomoshere storage. 2. Decreasing the pressure of chamber atmosphere to about 20 cmHg showed the best result among several pressure conditions. 3. As for the surface treatment of the apples, poly-ethylene film wrapping showed to be the most favorable method in a short-term experiment. In a long-term experiment, however, poly-ethylene film wrapping seemed to cause apples rot. Poly-vinyl acetate coating seemed to keep the apples from color changing, but it caused an unpleasant odor and a peculiar taste. No significant effect was observed in Gibberellin. 4. Total sugar and reduced sugar of apples were decreased after a certain period of increasing. Acid and Vitamin C, however, gradually decreased from the beginning of storage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.453-453
• /
• 2009

Wafer 태양전지와 Back sheet 및 기타 소재를 사용하는 기존의 Photovoltaic Module은 투과성이 존재하지 않으므로 본 논문에서는 태양전지 모듈의 투과특성을 발휘할 수 있는 Glass to Glass (GtG) Type의 Photovoltaic module에 대해 그 투과 특성 및 효율과의 관계를 분석하였다. 먼저 Module용 소재 중 Poly vinyl butyral (PVB) 및 Ethylene vinyl acetate(EVA) sheet의 Transmittance와 Haze 특성을 분석하였다. GtG 타입의 Photovoltaic Module은 약 90%정도의 투과율을 갖는 강화유리 및 Haze가 없는 PVB sheet를 사용하여 1m $\times$ 1m 크기로 제작하였다. GtG 타입으로 제조한 모둘 중 Cell 16EA를 사용한 모듈은 Cell 25EA를 사용한 모듈에 비해서 36% 투과율이 증가하였으나 효율 면에서 38%감소하였다. 최종적으로 GtG 타입 Module의 효율과 투과율에 관련된 식을 각각 정립하였다.

• Korean journal of food and cookery science
• /
• v.19 no.4
• /
• pp.439-446
• /
• 2003

This study was performed to investigate the change in the chemical components of red pepper powder using different packaging materials and various storage conditions. Red pepper powders with 11 and 15% initial moisture content were packed with five different materials and stored at different temperatures (0, 20, and 30 C) for a one year period. Over the storage period, each combination was periodically sampled, and examined for composition changes. The five packaging materials were: linear low density polyethylene(LLDPE), nylon/LLDPE(Ny/LLDPE), saran coated ethylene vinyl acetate copolymer/linear low density polyethylene(B650), nylon/Tie/nylon/ethylene-vinyl alcohol copolymer/nylon/Tie/LLDPE(RDX-2787) and oriented polypropylene/alumimum/LLDPE(OPP/Al/LLDPE), and the three storage conditions were (28.3${\pm}$1.0)$^{\circ}C$ with (15.5${\pm}$2.8)% relative humidity, (18.6${\pm}$0.5)$^{\circ}C$ with (46.6${\pm}$4.9)% RH, and (0${\pm}$2)$^{\circ}C$ with (80${\pm}$10)% RH, respectively. The moisture contents of all samples changed according to the relative storage humidity, except those of the samples packed with OPP/Al/LLDPE, which remained constant throughout the storage period. The capsaicinoids content of the red pepper powder did not change significantly for 6 months, but gradually decreased after that until about 85% of the original amount remained at the final stage of storage. The ASTA color values of all samples decreased gradually throughout the storage period. The higher the storage temperature, the more severe the deterioration. The color deterioration seemed greatly related to the existence of oxygen, as the deterioration was especially severe in the samples packed with LLDPE and B650, where the oxygen transmission rate were highest among the five packaging materials.

• Elastomers and Composites
• /
• v.52 no.2
• /
• pp.105-113
• /
• 2017

The curing behavior, mechanical properties, hot-air aging resistance, abrasion properties,thermal properties, etc., of EVM/EPM/APP (ammonium polyphosphate)/DPER (dipentaerythritol)/EG (expandable graphite) and EVM/EPM/ATH (aluminium trihydroxide) flame retarding systems in ethylene vinyl acetate rubber (EVM) blends with EPM (ethylene propylene rubber) were sequentially examined. For both flame retarding systems, the torque values increased with the content of EPM rubber and with the vulcanization time. As the content of EPM rubber increased, the scorch time became shorter, whereas the optimum cure time followed an increasing trend. For the EVM/EPM/APP/DPER/EG flameretarding system, as the content of EPM rubber increased, the hardness did not change,whereas the tensile strength and elongation at break decreased. A hot-air aging resistance test at $150^{\circ}C$ showed that the heat resistance decreased with the EPM content regardless of the kinds and contents of flame retardants. As the EPM content increased, the abrasion rate became higher and the abrasion resistance of the EVM/EPM/APP/DPER/EG flame retarding systems exceeded that of the EVM/EPM/ATH flame retarding counterparts. In comparison with the EVM/EPM/ATH flame retarding systems, the thermal stability of the EVM/EPM/APP/DPER/EG flame retarding system showed an increasing tendency.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.47 no.1
• /
• pp.110-122
• /
• 2023

The COVID-19 pandemic increased people's time at home and caused an 80% increase in noise disputes between floors. The purpose of this study is to propose suitable materials for making indoor shoes (insoles) to minimize noise between floors. Subjects without back pain and leg-related disease (e.g. arthritis, etc.) from three different age groups (childhood, adolescence, and adulthood) were recruited for the study. Five polymer insole materials were considered: Chloroprene Rubber (CR foam), Ethylene Propylene Diene Monomer (EPDM foam), Natural Latex foam, Ethylene Vinyl Acetate (EVA foam), and Polyurethane (PU foam). From these materials, 20 combinations were prepared and randomly tested for noise and vibration. The results revealed a significant difference in noise and vibration levels based on the type of material used and the age of the subject. Nevertheless, all materials under consideration successfully reduced noise and vibration; in particular, type A-C greatly decreased. The CR foam material was especially effective at noise and vibration reduction (p<.01). This study suggests that adding insoles into socks that children wear at home could reduce noise vibration and disputes between floors.

• Applied Chemistry for Engineering
• /
• v.8 no.6
• /
• pp.979-984
• /
• 1997

Test specimens of polymer-cement concrete composites were prepared using styrene-butadiene rubber(SBR) latex, ethylenevinyl acetate(EVA) and polyacrylic ester(PAE) emulsions as polymer dispersions in cement modified system at constant slump($10{\pm}0.5cm$), then compressive and flexural strengths water absorption, pore size distribution, and microstructures were investigated. Compressive and flexural strengths of these composites were remarkably improved with an increase of polymer-cement ratio. These composites had a desirable pore size distribution against frost damage due to a small capillary pore volume. Continuous polymer film was able to form in higher than 15% of polymer cement ratio.