• 수산해양기술연구
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• 제43권4호
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• pp.281-290
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• 2007

This study was aimed not only to develop the gill net and trap made of biodegradable monofilaments in order to prevent a ghost fishing and to protect marine ecosystem, but also to analyze their spinning process and physical properties. Results showed that the spinning speed of biodegradable polybutylene succinate(PBS) monofilament was estimated to be approximately 100m/min when spinning temperature and cooling water temperature were adjusted at $180^{\circ}C$ and $3^{\circ}C$, respectively. The breaking loads of PBS monofilaments were estimated to be $35.3kg/mm^2$ at ${\phi}0.2mm$, $46.5kg/mm^2$ at ${\phi}0.3mm$, and $49.7kg/mm^2$ at ${\phi}0.4mm$ in the dry condition, respectively. However, its breaking loads in the wet condition were reduced by 2.4-5.5%, compared to those in the dry condition. The knotted strength of PBS monofilament at ${\phi}0.2mm$ was estimated to be 98.6% of PE in the dry condition. The breaking load of PBS monofilament at ${\phi}0.3mm$ was evaluated to be 81.8% of PA, and its softness showed 3 times less than that of PA in the wet condition. The breaking load of PBS monofilament at ${\phi}0.4mm$ was 95.3% of PA, and its softness showed 1.6 times less than that of PA in the wet state. However, the load elastic elongations of two kinds of monofilaments were estimated to be 1% higher than that of PA.

• 접착 및 계면
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• 제10권2호
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• pp.106-112
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• 2009

본 연구에서 처음으로 생분해성 라이오셀 직물과 poly(butylene succinate) (PBS)로 이루어진 바이오복합재료가 성공적으로 제조되었다. 0, 30, 40, 50 그리고 60 wt%의 서로 다른 함량의 라이오셀직물을 포함하는 라이오셀/poly(butylene succinate) 바이오복합재료는 sheet interleaving 방식으로 압축성형에 의해 제조되었다. 바이오복합재료의 층간전단강도, 인장 및 굴곡 특성, 열변형 온도, 열팽창 거동 및 열안정성에 미치는 라이오셀직물 함량의 영향을 조사하였다. 특성들은 직물함량에 크게 의존하였으며, 그 결과들은 서로 일치하였다. 라이오셀직물을 수지에 도입하는 것이 poly(butylene succinate)의 여러 가지 특성 향상에 두드러진 역할을 하는 것으로 확인되었다. 라이오셀직물이 중량비로 50%일 때, 바이오복합재료의 가장 우수한 층간전단강도, 인장, 굴곡 및 열적 특성이 얻어졌다.

• 청정기술
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• 제11권2호
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• pp.57-67
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• 2005

에폭시 수지는 ECH(Epichlorohydrin)와 BPA(Bisphenol-A)를 원료로 가성소다 존재 하에 탈수응축 반응을 통해 생성되며 반응 부산물로 소금물이 폐수로 발생되는데 이를 Brine이라 부르며 글리시돌과 같은 에멀젼 상태의 ECH 유도체와 수지성 폴리머를 함유하는 알카리성 폐수이다. 이러한 폐수는 폐수처리 과정에서 반응기 내부와 배관 내벽에 폴리머 입자가 침적 및 응고되어 plugging을 일으키는 등 전체적으로 후처리 공정에서 fouling 현상이 발생되고 있는데 이는 미생물의 분해 활성도를 급격히 떨어뜨려 폐수처리 효율이 낮아지는 문제점을 야기 시키고 있다. 본 연구에서는 무기 응집제와 유기 고분자 응집제를 이용하여 에폭시 수지 생산 공정에서 발생하는 brine 폐수에 존재하는 ECH 유도체와 수지성 폴리머를 반고상 슬러지 형태로 응집 및 침전시킴으로써 fouling 현상을 일으키는 요인을 제거하고자 최적의 응집반응 조건을 도출하였고 경제성 분석 등 이를 실제 공정에 적용할 수 있는 방안을 제시하고자 하였다.

• Fibers and Polymers
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• 제7권4호
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• pp.372-379
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• 2006

The surface topography, tensile properties, and thermal properties of ramie fibers were investigated as reinforcement for fully biodegradable and environmental-friendly 'green' composites. SEM micrographs of a longitudinal and cross sectional view of a single ramie fiber showed a fibrillar structure and rough surface with irregular cross-section, which is considered to provide good interfacial adhesion with polymer resin in composites. An average tensile strength, Young's modulus, and fracture strain of ramie fibers were measured to be 627 MPa, 31.8 GPa, and 2.7 %, respectively. The specific tensile properties of the ramie fiber calculated per unit density were found to be comparable to those of E-glass fibers. Ramie fibers exhibited good thermal stability after aging up to $160^{\circ}C$ with no decrease in tensile strength or Young's modulus. However, at temperatures higher than $160^{\circ}C$ the tensile strength decreased significantly and its fracture behavior was also affected. The moisture content of the ramie fiber was 9.9 %. These properties make ramie fibers suitable as reinforcement for 'green' composites. Also, the green composites can be fabricated at temperatures up to $160^{\circ}C$ without reducing the fiber properties.

• 폴리머
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• 제37권3호
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• pp.294-301
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• 2013

Polymersomes made of biodegradable triblock copolymers based on poly(fumaric acid-co-sebacoyl chloride)/PEG (PEG-co-P(FA/SC)-co-PEG) were prepared and studied in aqueous solutions. TEM confirmed the formation of vesicles in aqueous media. Aggregation behavior of the copolymers was studied by fluorescence spectroscopy of 8-anilino-1-naphthalenesulfonic acid, and the critical aggregation concentration (c.a.c.) of the copolymer was found to be ${\sim}26.2{\mu}M$ indicating desirable stability of the vesicles. Dynamic light scattering revealed that the size of the vesicles was distributed within the range of 170-270 nm. Turbidity measurements confirmed the relative short-term stability of the polymersomes. Carboxyfluorescein, a hydrophilic compound, was simply encapsulated in the vesicles during polymersome preparation. The release of encapsulant from the polymersomes at 25 and $37^{\circ}C$ lasted about 3 weeks, and the rate of release followed a first-order kinetics. The release is speculated to be primarily carried out through diffusion. These results confirm that these polymersomes are promising as controlled-release carriers of various drugs.

• Advances in materials Research
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• 제11권3호
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• pp.191-209
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• 2022

Very slow degradation of synthetic based polymers has created a severe environmental issue that increased awareness towards research in polymers of biodegradable property. Soy protein isolate (SPI) is a natural biopolymer used as matrix in green composites but it has limitations of low mechanical properties and high water sensitivity. To enhance mechanical properties and reduce water sensitivity of Jute-SPI composites, SPI was modified with pine rosin which is also a natural cross-linking agent. 30% glycerol on the weight basis of a matrix was used as a plasticizer. The fibre volume fraction was kept constant at 0.2 whereas the pine rosin in SPI ranged from 5% to 30% of the matrix. The effects of pine rosin on mechanical, thermal, water sensitivity and surface morphology have been characterized using various techniques. The mechanical properties and water absorbency were found to be optimum for 15% pine rosin in Jute-SPI composite. Therefore, Jute-SPI composite without pine rosin and with 15% pine rosin were chosen for investigation through characterization by Fourier transforms infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), X-Ray diffraction (XRD) and Scanning electron microscope (SEM). The surface morphology of the composite was influenced by pine rosin which is shown in the SEM image. TGA measurement showed that the thermal properties improved due to the addition of pine rosin. Antimicrobial test showed antimicrobial property in the composite occurring 15% pine rosin. The research paper concludes that the modification of SPI resin with an optimum percentage of pine rosin enhanced mechanical, thermal as well as water-resistant properties of jute fibre reinforced composites.

• 청정기술
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• 제19권4호
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• pp.401-409
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• 2013

폐플라스틱에 의한 환경오염 증가로 생분해성 고분자에 대한 관심이 커지고 있다. 본 연구에서는 생분해성 고분자인 폴리 L-락타이드(polylactic acid, PLA)와 폴리 L-락타이드(polylactic acid, PLA)/폴리 부틸렌 숙신산(polybutylene succinate, PBS)(90/10)수지를 기지재료로 하고 유기 크로사이트(cloisite ) 20을 나노 클레이(clay) 20으로 사용하여 이축압출기에서 Clay-20 함량별 로 압출시켜 나노복합체를 제조하였다. 사출성형기로 사출성형시편을 제조하여 나노복합체의 열적, 기계적, 형태학적 및 라만 분광학 특성을 시차열량분석기(differential scanning calorimeter, DSC), 인장시험기, 주사전자현미경(scanning electron microcopy, SEM), 라만-현미경 분광광도계로 조사하였고, 또한 가수분해특성을 조사하였다. 시차열량분석기와 주사전자현미경 시험 결과에서 PLA/Clay-20과 PLA/PBS/Clay-20 나노복합체의 결정화도가 Clay-20 함량이 증가함에 따라 증가하였고, Clay-20과 PLA 및 PLA/PBS 수지가 서로 상용성이 있는 것으로 확인되었다. 또한 Clay-20 함량이 증가함에 따라 두 나노복합체의 인장강도는 감소하지만 신도, 충격강도, 인장탄성률 및 굴곡탄성률이 증가하였다. 특히 Clay-20이 5 wt% 첨가된 PLA/Clay-20과 PLA/PBS/Clay-20 나노복합체의 충격강도는 순수 PLA와 PLA/PBS (90/10) 보다 2배 이상으로 증가하였다. Clay-20 3 wt% 첨가된 PLA/Clay-20 나노복합체의 가수분해속도는 순수 PLA 가수분해속도보다 두 배 정도 빨랐다. 이는 유기화 처리된 Clay-20 나노입자 표면의 친수성으로 계면에서 가수분해가 쉽게 일어나기 때문인 것으로 판단된다. 본 연구에서 적당량의 Clay-20 첨가로 PLA의 기계적특성 개선과 생분해 특성 조절 가능성을 확인하였다.

• 펄프종이기술
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• 제47권5호
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• pp.112-119
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• 2015

The pulp mold attract the increasing concern as recyclable, biodegradable, and eco-friendly packaging materials. In order to broaden the applicability of the pulp mold as substitutes of the expanded styrofoam, the properties of various raw materials for the pulp mold were evaluated and the way for improving water resistance properties of the pulp mold were also tested by applying some additives. The higher value in the fines contents and in the water retention value were shown for the TMP (thermomechanical pulp), which resulted in the bulkier pulp mold with the higher moisture absorption property. In case of water resistance properties, the pulp mold made of white ledger stock showed the higher value in water contact angle and very slow water absorption rate. The addition of oil palm EFB fiber showed the improvement in the water resistance of the pulp mold made of UBKP. The effects of various additives on the improvement in the water resistance properties of the pulp mold were tested by using AKD, PVAm, epoxy resin. The application of AKD leaded to the higher increase in the water resistance. The results in this study showed the effects of AKD for the pulp mold could be improved and optimized by the application with fixing agent and by the ageing treatment after production.

• 한국물환경학회지
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• 제21권2호
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• pp.125-131
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• 2005

Natural organic matter(NOM) is defined as the complex matrix of organic material and abundant in natural waters. It affects the performance of unit operations for water purification. Several kinds of analytical indicators such as DOC, specific ultraviolet absorbance(SUVA), apparent molecular weight (AMW), fractionation and high performance size exclusive chromatography(HPSEC) have been used to understand characteristics and variations of NOM. This study aims to evaluate the characteristics of NOM in the Geum River system comprising with stream flows and reservoirs. It was identified that SUVA denoting the portion of humic substance in water ranged within 1.60~3.36. Using resin adsorbents, dissolved organic carbon(DOC) was fractionated into three classes: hydrophobic bases(HOB), hydrophobic acids(HOA) and hydrophilic substances(HI). HI dominates in all samples, collectively accounting for more than 62% of the DOC. HOA was the second dominated fraction and it varied considerably but accounted for about 30% of the DOC. The distribution of high molecular weight(HMW) measured by HPSEC being used to determine the molecular weight distribution of aquatic humic substances was 40.1% and 38.7% in reservoir and stream flow, respectively. The distribution of low molecular weight(LMW) in stream flow was 13.2% higher than that in reservoir. And apparent molecular weight less than 1KDa, which include the molecular weight of hydrophilic organic matter, occupied with 69.2% and 68.2% in stream flow and reservoir, respectively. While the molecular weight of 1 to 100 KDa including humic substances ranged with 18.6% and 21.6% in stream flow and reservoir, respectively. Seasonal variation of refractory dissolved organic carbon was similar to that of SUVA.

• 한국키틴키토산학회지
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• 제23권4호
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• pp.256-261
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• 2018

Recently, the number of cardiovascular disease-related deaths worldwide has increased. Therefore, the importance of percutaneous cardiovascular intervention and drug-eluting stents (DES) has been highlighted. Despite the great clinical success of DES, the re-endothelialization at the site of stent implantation is retarded owing to the anti-proliferative effect from the coated drug, resulting in late thrombosis or very late restenosis. In order to solve this problem, studies have been actively carried out to excavate new drugs that promote rapid re-endothelialization. In this study, we introduced hydrophilic drug, tauroursodeoxycholate (TUDCA), that improves the proliferation of endothelial progenitor cells and promotes apoptosis of vascular smooth muscle cells. In addition, we utilized shellac, which is a natural resin from lac bug to coat TUDCA on the surface of the metal. When using conventional coating method including biodegradable polymers and organic solvents, phase separation between polymer and drug occurred in the coating layer that caused incomplete incorporation of drug into the polymer layer. However, when using shellac as a coating polymer, no phase separation was observed and drug was fully covered with the polymer matrix. In addition, by adjusting the composition of coating solution and modifying the hydrophilicity of the metal surface using oxygen plasma, the surface roughness decreased due to the increased affinity between coating solution and metal surface. This result provides a method of depositing a hydrophilic drug layer on the stent.