• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.97-100
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• 2007

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• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.452-455
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• 2001

고분자/실리케이트 나노복합체란 고분자 매트릭스에 층상 구조의 점토 광물을 나노 스케일의 시트상의 기본 단위로 박리(exfoliation)ㆍ분산시켜 얻어진 복합체를 말한다. 실리케이트를 구성하는 두께 1nm 정도의 판으로 박리ㆍ분산시키기 때문에 5wt% 정도의 첨가량만으로도 고분자의 획기적인 물성 개선이 가능하다는 장점을 가지고 있다[1]. (중략)

• Polymer(Korea)
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• v.27 no.4
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• pp.370-376
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• 2003

Poly(DL-lactide-co-glycolide) nanoparticles were prepared by the modified spontaneous emulsification solvent diffusion method. Polymer solution was prepared by two water-soluble organic solvents, such as ethanol and acetone. Because of its biocompatible nature, PEG-PPG diblock copolymer was used as surfactant and stabilizer. The influence of several preparative variables on the nanoparticle formation, such as type and concentration of stabilizing agent, stirring methods, water/oil phase ratio and polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles, particle size and distribution were evaluated by the light scattering particle analyzer. As results, the particle size was 50-200 nm and dispersibility was monodisperse. It was found that the appropriate selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide a good yield and favorable physical properties of PLGA nanoparticles.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.95-101
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• 2012

To manufacture of a completely biodegradable and compostable biomass -based blend polymer film, two types of cellulose acetates(DS=2.4 and DS=2.7) were blended with 5 - 50 wt% of low average molecular weight polylactide(PLA) by mixing each polymer solution having same viscosity in 10 wt% methanol/dichloromethane. Their surface morphology, thermal and mechanical properties were studied. The chemical structures of blend films were confirmed by the fourier transform IR spectroscopy with attenuated total reflection(FT-IR ATR) spectrophotometer. Scanning electron microscope(SEM) photos of blend films of both CAs with less than 5 % of PLA showed homogeneous morphology. On the contrary, the other blends with higher than 20 wt% of PLA content showed a large phase separation with spherical domains. The thermal property of blend films was also analyzed with thermogravimetric analysis(TGA) and differential scanning calorimeter(DSC). The tensile strength of CA/PLA blend films was increased up to $820kg_f/cm^2$ for TAC/PLA and $600kg_f/cm^2$ for DAC/PLA.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.380-381
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• 2003

지방족 폴리에스터계 고분자인 폴리락타이드 (polylactide, PLA), 폴리글리콜라이드 (polyglycolide, PCA)는 생체친화성이고 생분해성을 나타낸다. 그리고, 전기방사는 크게는 수 마이크로에서 작게는 수십 나노크기의 지름을 가지는 초극세 섬유인 나노섬유의 제조 기술로서 기존의 섬유 방사방식과는 근본적으로 다른 새로운 방사기술로 산업적인 응용 가능성이 무한한 미래지향적 기술로 최근 주목을 받고 있다. 본 연구에서는 이러한 우수한 생분해성과 생체적합성을 가진 PCA와 PLA 고분자를 블렌드 하여 부직포로 얻을 수 있는 전기방사를 이용하였다. (중략)

• Polymer(Korea)
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• v.30 no.1
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• pp.28-34
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• 2006

A series of methoxypoly(ethylene glycol) $(MPEG)-poly(\varepsilon-co-L-lactide)$ (PCLA) diblock copolymers were synthesized by ring-opening polymerization of a mixture of $\varepsilon-caprolactone$ and L-lactide with different ratios in the presence of $Sn(Oct)_2$. The characterization of MPEG-PCLA diblock copolymers were examined by $^1H-NMR$, GPC, DSC, and XRD. Kinetic study on ring-opening polymerization of monomer mixtures was carried out in various conditions such as a variation with polymerization time, amount of catalyst, and temperature. The highest conversion obtained in 1.2 ratic of initiator venn catalyst at $110\;^{\circ}C$. The biodegradable characterization of MPEG-PCLA diblock copolymers in aqueous solution was carried out by using GPC for $1\~14$ weeks. The biodegradability of MPEG-PCLA diblock copolymers increased as the L-lactide content of diblock copolymers increased. In conclusion, we confirmed the dependence of polymerization rate according to various conditions. In addition, we can control the biodegradability of MPEC-PCLA diblock copolymers by changing the ratio of PCL and PLA block segment.

• Polymer(Korea)
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• v.28 no.3
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• pp.211-217
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• 2004

The sol to gel transition of aqueous solution of block copolymers consisting of methoxy poly (ethylene glycol) (MPEG) and biodegradable polyesters such as $\varepsilon$-caprolactone and L-lactide was investigated as a function of temperature. MPEG-PCL was prepared by ring opening polymerization of $\varepsilon$-caprolactone in the presence of HClㆍEt$_2$O as monomer activator at room temperature. Also, MPEG-PLLA was prepared by ring opening polymerization of L-lactide in the presence of stannous octoate at 115$^{\circ}C$. The properties of block copolymers were investigated by $^1$H-NMR, IR, and GPC as well as the observation of thermo sensitive phase transition in aqueous solution. As the hydrophobic block length increased, the sol to gel transition temperature increased and curve of that steepen to lower concentration. To confirm the gel formation at body temperature, we observed the formation of gel in the mice body after injection of 20 wt% aqueous solution of each block copolymer. After surging, we investigated the gelation in mice. The results obtained in this study confirmed the feasibility as biomaterials of injectable implantation for controlled release of drug and protein delivery.

• Polymer(Korea)
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• v.31 no.3
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• pp.201-205
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• 2007

Biodegradable polymers such as polylactide, polyglycolide and poly (lactide- co-glycolide) (PLGA) have been extensively investigated because of easily controlled drug release rate, completely degradable materials without the toxic by-product, and good biocompatibility. But, according to the bulk erosion property of PLGA in vitro test, it had the disadvantage that first-order release reduced releasing amount slowly after excessive initial burst. In this study we used PLGA powder obtained through recrystallization to revise bulk erosion property of PLGA. The PLGA used in this study was prepared by vacuum drying method and to estimate release profiles of BCNU loaded PLGA wafer. We also evaluated the release profile of drug with the water soluble additive. It was found that the drug loaded PLGA recrystallized by vacuum drying method exhibited the initial burst and the constant rate of drug release compared to that prepared by a conventional method.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.529-532
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• 2008

본 연구에서는 생체 적합성이 뛰어난 HA와 생분해성고분자인 PLLA와의 낮은 혼합성을 개선하기 위하여 HA를 화학적으로 개질하여 PLLA와의 특정 상호 작용력을 부여함으로서 HA/PLLA 복합체의 기계적 물성을 높이는 연구를 수행하였다. TGA분석으로부터 개질된 HA은 6wt% lactic acid 와 7 wt% DLA가 반응하였으며 HA에 비하여 유기용매에 대한 분산안정성이 증가하는 것으로 나타났다. 용매-비용매 방법으로 제조된 HAAD/PLLA 복합체는 DSC측정으로부터 개질된 HA의 DLA 사슬과 PLLA의 LLA사이에 스테레오 콤플렉스를 형성에 의하여 HA가 PLLA사이에 균일하게 분산되었고 상분리 구조의 미개질 HA/PLLA 복합체에 비하여 기계적 물성이 증가하는 것으로 나타났다.

• Clean Technology
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• v.19 no.4
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• pp.401-409
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• 2013

BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.