• 펄프종이기술
• /
• 제36권5호
• /
• pp.53-61
• /
• 2004

[ $Poly(_{D}-ldactide)\;(_{D}-PLA)$ ] was synthesized to have low molecular weight for miscible blends with a high molecular $poly(_{L}-lactide)\;(_{L} -PLA)$. The blends were prepared by dissolving the two components of $_{L}-PLA\;and\;_{D}-PLA\;(w/w)$ in chloroform (l00/0, 90/10, 70/30, 50/50, 30/70, 0/100). The miscibility of these miscible blends was characterized by gel-permeation chromatography (GPC), differential scanning calorimetry (DSC), and the selective degradability by enzymes (proteinase K, subtilisin and $\alpha$-chymotrypsin). The coating efficiency of PLA blends onto paper was determined and the degrading activity cellulases by on these blends. The miscibility, coating efficiency and enzymatic degradability of these blends were decreased according to increasing of $_{D}-PLA$ blending part. Such results were attributed to the extent of coating application of PLA, with better miscibility (compatibility), coating efficiency and degradability due to a higher $_{L}-PLA$ content.

• Bulletin of the Korean Chemical Society
• /
• 제31권9호
• /
• pp.2557-2560
• /
• 2010

To assay for antioxidant capacity of natural products considered important in producing human health benefits, a practical and economical method using pellet techniques was developed. A standard visualizing reagent, 1,1diphenyl-2-picryl-hydrazyl (DPPH), was mixed with a water-miscible polyvinyl alcohol (PVA), serving as a solid phase support for the DPPH reagent. A DPPH pellet was prepared by dropping a small volume of the DPPH solution onto PET film, and drying in an oven. The PVA-based DPPH pellet was dissolved into water, in which the water-miscible PVA plays as a non-ionic surfactant to help the DPPH reagent to be dissolved into the solvent. Using the DPPH assay, the antioxidant capacity of water-soluble extracts of black soybean, barley, green tea, and green gram was examined. Among the natural products tested, green tea showed the highest antioxidant capacity. This PVA-based DPPH antioxidant assay can be further applied in the natural food, raw plant material, and health product inspection field.

• 폴리머
• /
• 제24권5호
• /
• pp.682-689
• /
• 2000

고분자의 구조설계를 통해서 단상의 블렌드를 제조하기 위해서는 고분자 반복 단위간의 열역학적 정보가 필수적으로 요구된다. 본 연구에서는 블렌드를 구성하는 각 성분간의 상호작용 에너지를 결정하고 이를 이용하여 단상의 블렌드를 제조하는 방법을 제시하였다. 이를 위하여 폴리카보네이트들과 여러 종류의 폴리메타크릴레이트간의 상용성을 조사하였으며, 이를 바탕으로 고분자 구조를 조절하여 단상의 블렌드를 제조하였다. 또한 단상의 블렌드에 포함된 각 고분자간의 상호작용 에너지는 LCST 거동에 의한 상분리 온도와 상태방정식을 이용하여 정량화 하였다.

• Advanced Composite Materials
• /
• 제17권4호
• /
• pp.333-341
• /
• 2008

A novel manufacturing method for hybrid composites filled with carbon nanotubes (CNTs) and aramid fibers is proposed. To disperse the CNTs in the epoxy matrix with the presence of aramid fibers, CNT/polyethyleneoxide (PEO) composites are prepared and utilized because PEO is miscible in the epoxy resin. After thin films are made of the CNT/PEO composite and placed together with the aramid fibers, the epoxy resin is infused to them. The PEO is dissolved in the epoxy and then the CNTs are dispersed in the PEO/epoxy matrix between aramid fibers before the pre-heated matrix is cured. It is found that the PEO is completely miscible with the epoxy resin and CNTs are dispersed well in the space between the aramid fibers.

• Macromolecular Research
• /
• 제12권1호
• /
• pp.94-99
• /
• 2004

We have performed Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) studies on blends of poly(vinyl phenol) (PVPh) with poly(n-alkylene 2,6-naphthalates) containing alkylene units of different lengths. The results indicate that each poly(ethylene 2,6-naphthalate) (PEN) and poly(trimethylene 2,6-naphthalate) (PTN) blend with PVPh is immiscible or partially miscible, but blends of poly(butylene 2,6-naphthalate) (PBN) with PVPh are miscible over the whole range of compositions in the amorphous state. FTIR spectroscopic analysis confirmed that significant degree of intermolecular hydrogen bonding occurs between the PBN ester carbonyl groups and the PVPh hydroxyl groups. The large difference in the degree of mixing in these blend systems is described in terms of the effect that chain mobility has on the accessibility of the ester carbonyl functional groups toward the hydroxyl groups of PVPh, which in turn impacts the miscibility of these blends.

• KSBB Journal
• /
• 제9권3호
• /
• pp.312-318
• /
• 1994

Ac-Tyr-OH의 에스테르화 반응은 water/water­m miscible organic solvent를 이용하여 단일상계 (one phase system) 조건 하에서 ${\alpha}$-chymotrypsin의 촉 매작용으로 진행하였으며, 그 결과는 다음과 같다. Ac- Tyr-OH(1OmM)이 함유된 에탄올(lOml)[ 4 % %(v/v) buffer 함유] 용액에서 ${\alpha}$-chymotrypsin의 촉매작용에 의한 에스테르화 반응에 영향을 마치는 흡착물질 chitin, chitosan, Sephadex G-25 및 G-50, CM 및 DEAE-Sephadex, CM 및 DEAE cellulose 중 chitin을 첨가하였을 경우, 에스테르화 수율이 62%로 가장 높았다. 그리고 에스테르화 수 율에 마치는 최적반응조건은 chitin/${\alpha}$-chymotry psm의 비가 20(w/w), 온도 $35^{\circ}C$, pH 8.0 빛 유기 용매에 첨가된 수용액의 농도는 2%(v/v)였다. 또한, water/water-miscible organic solvent system 에서 chitin의 첨가는 효소의 안정성에 기여하는 것으로 나타났다. 최적반응조건 하에서 에스테르화 반응의 수율, Km 및 Vmax 값은 각각 93%, 3.093mM 및 1.088mM/mg/hr이었다.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회(1)
• /
• pp.501-503
• /
• 2005

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
• /
• pp.157-160
• /
• 2006

• Fibers and Polymers
• /
• 제4권4호
• /
• pp.188-194
• /
• 2003

Phase behavior and spinodal phase separation kinetics in binary blends of a random copolymer of vinylidene fluoride and trifluoroethylene (75/25) [P(VDF/TrFE)] and poly(l,4-butylene adipate) (PBA) have been investigated by means of optical microscopic observation and time-resolved light scattering. The blends exhibited a typical lower critical solution temperature (LCST)∼${34}^{\circ}C$ above the melting temperature of the P(VDF/TrFE) crystals over the entire blend composition range. P(VDF/TrFE) and PBA were totally miscible in the temperature gap between the melting point of P(VDF/TrFE) and the LCST. Temperature jump experiments of the 3/7 P(VDF/TrFE)/PBA blend were carried out on a light-scattering apparatus from a single-phase melt state (${180}^{\circ}C$) to a two-phase region (205∼${215}^{\circ}C$). Since the late stage of spinodal decomposition (SD) is prevalent in the 3/7 blend, SD was analyzed using a power law scheme. Self-similarity was preserved well in the late stage of SD in the 3/7 blend.

• 폴리머
• /
• 제26권6호
• /
• pp.737-744
• /
• 2002

결정성 폴리부틸렌나프탈레이트 (PBN)와 비결정성 폴리비닐페놀 (PVPh)로 구성된 2 성분계 고분자 블렌드의 열역학적 상용성을 시차주사열분석 (DSC)과 푸리에변환 적외선 (FTIR) 분광분석으로 조사하였다. PBN/PVPh 블렌드의 DSC 측정 결과로부터 블렌드 전 조성에서 단일 유리전이온도 (T$_{g}$ )가 확인되었으며, 블렌드 내의 PVPh 조성이 증가함에 따라 PBN 결정질의 용융점(T$_{m}$ ) 강하가 관찰되었다. 고분자 블렌드의 단일 T$_{g}$ 및 T$_{m}$ 강하 현상은 PBN/PVPh 블렌드가 분자 수준에서의 열역학적 상용성이 있음을 보여준다. PBN의 에스테르 카르보닐기와 PVPh의 히드록실기 사이에 강한 분자 간 수소결합이 형성됨을 FTIR 분석에 의하여 확인할 수 있었다.