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용융블렌드를 이용한 PLA/PEG 블록 공중합체의 제조
윤철수,지동선,Yoon, Cheol-Soo,Ji, Dong-Sun 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.5
PLA/PEG blends composed of poly(lactic acid) (PLA) and poly (ethylene glycol) (PEG) were prepared via melt blending for bioabsorbable filament sutures. The effects of blend composition and blending time on the alcoholysis or esterification in the PLA/PEG blends were investigated. Their properties due to PLA/PEG block copolymer were characterized by $^1$H-NMR, GPC, and DSC analyses. Consequently, PLA/PEG block copolymers were formed during the melt blending by alcoholysis or esterification from a new peak due to -CH$_2$(c') appeared at 4.3 ppm. In addition, the molecular weights of the blends processed in Haake Rheomix for 10$\sim$30 minutes at 220 $^{\circ}C$ under screw speed 20 rpm decreased with increasing PEG contents and blending time. Their thermal properties such as melting temperature and heat of fusion due to PLA in the blends decreased with increasing PEG contents and blending time. However, their melting temperature and heat of fusion due to PEG increased with an increase of PEG content under constant blending time.
열유도상분리법에 의한 미세다공성 폴리에틸렌 중공사막의 제조에 관한 연구
지동선,공용운 단국대학교 1999 산업기술연구 Vol.1 No.-
The solid-liquid phase separation of the high density polyethylene(HDPE) hollow fiber membrane prepared via thermally induced phase separation process was thermodynamically investigated. As the amount of liquid paraffin(LP) used as a diluent increased, the equilibrium melting temperature given Hoffman-Weeks plots decreased. The value of Flory-Huggins interaction parameter obtained from the melting point depression in the HDPE/LP blends was -0.43. The phase was not separated in the melt state since it had good miscibility. However, the solid-liquid phase separation occurred at lower temperatures. The temperatures of crystallization and phase separation decreased with increase in the cooling rate. As the amount of liquid paraffin and draft ratio increased, the flux of polyethylene hollow fiber membrane increased. It was found that the optimum blend ratio for microporous polyethylene hollow fiber membrane of HDPE/LP blends was determined to be 40/60. The flux of polyethylene glycol solution under the same applied pressure and time was less than that of pure water for HDPE/LP 40/60 and 50/50(wt%).
智東宣 단국대학교 1992 論文集 Vol.26 No.-
One factor influencing the comfort of fabrics for clothing is their resistance to the passage of water vapor. In this evaluation on the water vapor permeability of woven fabrics by response surface analysis, the water vapor transfer resistance of woven fabrics is a dependent variable, and three parameters of fabrics(i.e. thickness, porosity, and open free area) are simultaneously independent variables. The second order regression model on the water vapor transfer resistance(R_F) can be fitted from the method of least squares by response surface analysis. And the estimated value of water vapor transfer resistance of worsted fabrics made of ring spun yarns was approximately 0.82cm at the stationary point.
지동선,김현성 단국대학교 1999 산업기술연구 Vol.1 No.-
The optimum conditions of loess dyeing were investigated to improve the color fastness and antibacteria properties of wool fabric dyed with the loess at various conditions such as loess, H_2SO_4. Na_2SO_4, concentration, time and temperature. With the increase in concentrations of loess and H_2SO_4, the dyeing temperature, and the dyeing time, the K/S values of the samples increased. But with the increase in concentration of Na_2SO_4, used as a retarder, the K/S values of the samples decreased. It was found that the optimum conditions of loess dyeing in order to give the color fastness to dry cleaning were loess 3∼5 % o.w.f., H_2SO_4 2∼3 %(v/v), Na_2SO_4, 5 % o.w.f., dyeing temperature 90℃, and dyeing time over 35 minutes. The results of antibacteria tests suggested that the antibiosis of wool fabric dyed with the loess is better than that of the undyed.