• 폴리머
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• 제31권5호
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• pp.385-392
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• 2007

Poly (N-vinylpyrrolidone) (PVP) groups were grafted onto a poly(3-hydroxybutyrate-co-3-hydroryvalerate) (PHBV) backbone in order to modify its properties and synthesize a novel biocompatible copolymer. The crystallization behavior of PHBV and grafted PHBV was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). During the cooling-induced crystallization process, the crystallization temperature and the crystallization rate of the grafted PHBV decreased with increasing PVP weight fraction. On the heating scans of all grafted PHBV samples, a new crystallization exothermic peak appeared at almost the same temperature, suggesting the operation of a recrystallization process, while the melting temperature ($T_m$) and the apparent enthalpy of fusion (${\Delta}H_f$) were not affected by graft modification. During the isothermal crystallization process at the same temperature, the presence of side PVP groups decreased the spherulitic growth rate and the spherulitic band spacing with increasing PVP weight fraction in samples.

• 폴리머
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• 제26권6호
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• pp.792-802
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• 2002

본 연구에서는, 방사선($^{60}$Co ${\gamma}$-rays) 가교를 이용하여 poly(vinyl alcohol)(PVA)/poly(N-vinylpyrrolidone)(PYP)/글리세린/키토산의 혼합물로부터 하이드로겔을 제조하였다 하이드로겔이 상처 치료용 드레싱으로 사용될 수 있는지 예측하기 위해 겔화율, 팽윤도, 겔강도 같은 기계적 성질을 측정하였다. PVV와 PVP의 조성비는 6 : 4, 키토산은 0.3 wt%, 글리세린은 0~5 wt%, PVA/PVP/글리세린/키토산 수용액의 고형분의 농도는 15 wt%이었다. 하이드로겔의 기계적 성질에 조사선량이 미치는 영향을 예측하기 위해 PVA/PVP/글리세린/키토산 혼합물에 25~60 kGy의 감마선을 조사하였다. 겔화율과 겔강도는 글리세린 조성비가 작을수록 조사선량이 커질수록 증가하였다. 팽윤도는 글리세린 조성비가 클수록, 조사선량이 작을수록 증가하였다. PVA/PVP/글리세린/키토산 하이드로겔에서 글리세린은 겔 모양의 변형을 막는다. 제조된 하이드로겔이 상업용 바셀린 거즈보다 치료 효과가 우수하였다.

• 폴리머
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• 제25권2호
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• pp.270-278
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• 2001

의료용 고분자로 널리 알려진 poly(vinylalcohol)(PVA)와 poly(N-vinylpyrrolidone)(PVP)를 이용하여 상처치료용 하이드로겔을 제조하였다. PVP 하이드로겔의 기계적 강도를 향상시키기 위해 PVA/PVP 혼합용액에 \"freezing and thawing (동결융해)\"을 반복한 후 방사선 ($^{60}$Co${\gamma}$-rays)을 조사하여 하이드로겔을 얻었다. PVA와 PVP의 조성비 (30 : 70 ~ 100 : 0), 동결융해의 반복횟수, PVA 분자량을 변화시키면서 PVA/PVP 하이드로겔의 겔화율, 팽윤도, 겔강도를 측정하였다. PVA/PVP 하이드로겔은 방사선 조사로만 제조되었을 때 보다 동결융해 반복 후 방사선조사했을 때 겔화율과 겔강도가 향상되었다. 이외에 동결융해의 반복정도에 따른 물성의 특징을 논의하였다.특징을 논의하였다.

• Advances in environmental research
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• 제3권2호
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• pp.107-116
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• 2014

This study aimed to synthesize dispersed and reactive nanoscale zero-valent iron (nZVI) with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), nontoxic and biodegradable stabilizer. The nZVI used for the experiments was prepared by reduction of ferric solution in the presence of PVP/VA with specific weight ratios to iron contents. Colloidal stability was investigated based on the rate of sedimentation, hydrodynamic radius and zeta potential measurement. The characteristic time, which demonstrated dispersivity of particles resisting aggregation, increased from 21.2 min (bare nZVI) to 97.8 min with increasing amount of PVP/VA (the ratios of 2). For the most stable nZVI coated by PVP/VA, its reactivity was examined by nitrate reduction in a closed batch system. The pseudo-first-order kinetic rate constants for the nitrate reduction by the nanoparticles with PVP/VA ratios of 0 and 2 were 0.1633 and $0.1395min^{-1}$ respectively. A nitrogen mass balance, established by quantitative analysis of aqueous nitrogen species, showed that the addition of PVP/VA to nZVI can change the reduction capacity of the nanoparticles.

• Transactions on Electrical and Electronic Materials
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• 제12권5호
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• pp.222-225
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• 2011

Lead zirconate titanate (PZT) films were fabricated on Pt/Ti/$SiO_2$/Si substrate by the sol-gel method using a sol containing poly(N-vinylpyrrolidone) (PVP). PVP in alkoxide solutions can suppress the condensation reaction in gel films during heat treatment, and increase the viscosity of alkoxide solutions. Single-phase PZT films as thick as 1 ${\mu}m$ were deposited by repetitive coating with successive third-step heat treatments at 150$^{\circ}C$, 350$^{\circ}C$ and 650$^{\circ}C$. After heat treatment, the films were crack free, and optically transparent. As a result, we demonstrated a PZT film with a PVP molar ratio of 0.5, which has a permittivity of 734, a dielectric loss of 0.042, a $P_r$ of 40.5 ${\mu}C/cm^2$ and an $E_c$ of 156 kV/cm.

• 공업화학
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• 제24권4호
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• pp.416-422
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• 2013

알지네이트에 은이온을 첨가하기 위하여, 질산은 수용액을 이용하여 은-알지네이트를 제조하였다. 본 연구에서는 은-알지네이트를 Poly vinylpyrrolidone (PVP) 수용액과 블렌드하였고, 전기방사는 블렌드 용액을 이용하여 수행하였다. 은-알지네이트/PVP 혼합 용액의 항균효과는 colony counting test로 대장균과 포도상 구균에 대해 확인하였다. 은-알지네이트/PVP 혼합용액의 전기방사 조건은 조성물의 농도를 다양하게 하여 방사거리 22 cm, 방사속도 0.01 mL/min, 전압 26 kV 조건하에서 수행하여 나노섬유를 제조하였다. 은-알지네이트 나노 섬유의 형태와 크기는 SEM과 Image J를 통해 확인하였으며, 전기방사된 SA5P15 섬유들의 평균 직경은 124 nm를 보였으며, 균일하게 방사되는 것을 확인하였다. SA5P15의 균 감소율은 24 시간 후 99.9%를 보였다.

• 폴리머
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• 제25권5호
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• pp.728-735
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• 2001

본 연구에서는, $^{60}cO$ 방사선 (${\gamma}$-rays) 가교를 이용하여 PVA/키토산과 PVP/키토산의 혼합물로부터 하이드로겔을 제조하였다. 하이드로겔이 상처 치료용 드레싱으로 사용될 수 있는지 예측하기 위해 겔화율, 팽윤도, 겔강도같은 기계적 성질을 측정하였다. PVA와 키토산 및 PVP와 키토산의 비는 97 : 3 ~ 90 : 10이고, PVA/키토산 및 PVP/키토산 용액의 고형분의 농도는 15wt% 이었다. 하이드로겔의 기계적 성질에 조사선량이 미치는 영향을 예측하기 위해 PVA/키토산 및 PVP/키토산 혼합물에 25~70kGy의 감마선을 조사하였다. 겔화율과 겔강도는 키토산 조성비가 작을수록, 조사선량이 커질수록 증가하였다 팽윤도는 키토산 조성비가 클수록, 조사선량이 작을수록 증가하였다.

• 접착 및 계면
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• 제20권2호
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• pp.66-70
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• 2019

소수성 폴리프로필렌 섬유의 표면을 상압 플라즈마 공정을 이용하여 표면처리하였다. 친수성으로 개질된 섬유를 수용성 폴리비닐프롤리돈 (poly(N-vinylpyrrolidone, PVP) 코팅액에 딥코팅하여 PVP 막을 형성하였다. 섬유 표면에 코팅된 PVP 막은 15 kGy 선량의 전자 빔 조사를 통해 가교되어, 폴리프로필렌 섬유의 표면이 PVP 하이드로젤로 균일하게 코팅된 것을 확인하였다. PVP 하이드로젤 코팅막의 두께는 코팅액의 농도를 조절하여 제어할 수 있었다. 단계적인 표면처리, PVP 코팅, 그리고 하이드로젤 막의 형성에 따른 특성은 접촉각, 전자현미경, 광학현미경 등을 통해 분석되었다.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1869-1874
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• 2010

By reducing PVP with $H_2NOH$.HCl and NaOH 2:2:1 mass ratios in aqueous ethanol, poly-N-vinyl pyrrolidone oxime [PVPO] was prepared with 92% yield. Applying the sol-gel concept, orthosilicic acid [OSA] was made by hydrolyzing TEOS with ethanol in 1:0.5 molar ratios using 1 N KOH aqueous solution as a catalyst. The OSA + PVPO + $_L$-Valine ($\alpha$-amino acid) were mixed with pure ethanolic medium in 1:2:2 mass ratios and refluxed at $78^{\circ}C$ and 6 pH for 6.5 h. A white residue of poly-N-vinyl pyrrolidone oximo-L-valyl-siliconate [POVS] appeared after 5 h. The heating of reaction mixture was stopped and the contents were brought to NTP. The residue formation of POVS was intensified with lowering a temperature and completely solidified within 5 h, was filtered using a vacuum pump with Whatmann filter paper no. 42. The residue of POVS was washed several times with 20% aqueous cold ethanolic solution and dried in vacuum chamber at $25^{\circ}C$ for 24 h. The MP was noted above $350^{\circ}C$. Structural and internal morphology were analyzed with IR and $^1H$-NMR, and SEM respectively. A drug loading and transporting ability of the POVS in water and at pH = 5 and 8 was determined chromatographically.

• Korea-Australia Rheology Journal
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• 제20권3호
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• pp.109-116
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• 2008

The effect of intermolecular aggregation induced by hydrophobic and electrostatic interactions on shear and elongational flow properties of aqueous acrylic thickener solutions is discussed. Complex shear modulus is determined at frequencies up to $10^4$ rad/s employing oscillatory squeeze flow. Extensional flow behavior is characterized using Capillary Break-up Extensional Rheometry. Aqueous solutions of poly(acrylic acid)(PAA)/poly(vinylpyrrolidone-co-vinylimidazole) (PVP-VI) mixtures exhibit unusual rheological properties described here for the first time. Zero-shear viscosity of the mixtures increases with decreasing pH and can exceed that of the pure polymers in solution by more than two orders of magnitude. This is attributed to the formation of complexes induced by electrostatic interactions in the pH range, where both polymers are oppositely charged. PAA/PVP-VI mixtures are compared to the commercial thickener Sterocoll FD (BASF SE), which is a statistical co-polymer including (meth) acrylic acid and ethylacrylate (EA) forming aggregates in solution due to "sticky" contacts among hydrophobic EA-sequences. PAA/PVP-VI complexes are less compact and more deformable than the hydrophobic Sterocoll FD aggregates. Solutions of PAA/PVP-VI exhibit a higher zero-shear viscosity even at lower molecular weight of the aggregates, but are strongly shear-thinning in contrast to the weakly shear-thinning solutions of Sterocoll FD. The higher ratio of characteristic relaxation times in shear and elongation determined for PAA/PVP-VI compared to Sterocoll FD solutions reflects, that the charge-induced complexes provide a much stronger resistance to extensional flow than the aggregates formed by hydrophobic interactions. This is most likely due to a break-up of the latter in extensional flow, while there is no evidence for a break-up of complexes for PAA/PVP-VI mixtures. These flexible aggregates are more suitable for the stabilization of thin filaments in extensional flows.