• Elastomers and Composites
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• v.47 no.2
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• pp.141-147
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• 2012

Silicone resin has no water-absorbing function because it is a strong hydrophobic polymer. However, addition of super absorbent polymer gives much better absorbency than that of conventional silicone resin. In this study, we developed novel silicone materials with water-absorbing function by choosing three types of amorphous acrylic super absorbent polymers with different particle sizes, determining the mixing ratio of the three polymers and applying the mixtures into two-component type silicone material for medical purpose. The change in the mechanical properties such as tensile strength, tear strength, compressive strength and hardness was investigated by varying the particle size and content ratio of the added super absorbent polymers while preparing the silicone resins. The absorbency of the silicone resins was measured over time. Additionally, the particle shape of the super absorbent polymers as well as the distribution within the silicone resin was observed using an optical microscope.

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.98-103
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• 2011

This study was done for the preparation of macromolecular material with UV-blocking features by adding the benzophenone group that is commonly used as a UV-absorbent and $TiO_2$ which is known to be a very stable material in chemical and physical aspects. Also, we compared the level of UV absorbency of the polymer produced from polymerization with previous materials and measured basic properties such as water content, refractive index and optical transmittance of produced contact lenses. The results of the measurement showed that the refractive index and water content of the contact lens with added UV-absorbent was 1.430~1.440 and 35.0~45.0% respectively, which was similar to that of previous contact lenses. Also, for optical transmittances of each wave length, contact lenses without the UV-absorbent was 89%, 88% and 89% respectively for UV-A, UV-B and visible light, indicating that the UV transmittance is very high though contrary with cases of contact lenses with added 2-hydroxy-4-methoxy-benzophenone and 2,4-dihydroxy-benzophenone which showed transmittances of 0% and 6% respectively for UV-A and UV-B showing a UV-blocking effect. Meanwhile, contact lenses with added $TiO_2$ showed transmittance of 6% and 51% respectively for UV-A and UV-B also showing a UV-blocking effect. The visible transmittance was 77~89% showing that it satisfies the visible transmittance required for ophthalmological materials.

• Journal of Adhesion and Interface
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• v.13 no.3
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• pp.137-144
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• 2012

Chemical functionalization of carbon nanomaterials (CNMs) is generally carried out for increasing interfacial adhesion between filler and polymer matrix for CNM-polymer nanocomposites. The chemically functionalized CNTs can produce strong interfacial bonds with many polymers, allowing CNT based nanocomposites to possess high mechanical and functional properties. Hence, increased surface adhesion can be measured indirectly by observing increased mechanical properties. However, there is a more direct way to observe interfacial bonds between polymer and CNM by measuring piezoresistivity behavior so that we can imagine the behavior of CNM particles in polymer matrix under deflection. Fuctionalization of MWCNT and rGO was carried out by oxidization reaction of MWCNT and rGO with $H_2SO_4/HNO_3$ solution. Electrical resistivities of MWCNT-PMMA and rGO-PMMA composites were decreased after functionalization because of the destructive fuctionalization process. Meanwhile, piezoresistivities of functionalized CNM-PMMA composites showed more sensitive behavior under the same deflection as compared to pristine CNM-PMMA composites. Therefore, mobility of CNM in polymer matrix was found to be improved with chemical functionalization.

• Food Engineering Progress
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• v.13 no.3
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• pp.169-175
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• 2009

Water soluble polysaccharides (WSP) and arabinogalactan of Portulaca oleracea L. (POL) were increased after extrusion and commercial cellulase treatment. Arabinose and galactose content increased more about 1.5 times than those of raw POL, and rhamnose also increased about 2.6 times in WSP. High molecular weight fraction (I) of POL depending on extrusion condition including Ext I, Ext II and Ext III degraded into low molecular weight fraction (II) about 37, 29, and 26%, respectively, ranged from 67,000-69,000 Da of molecular weight. Especially, the molecular weight and composition of WSP with extruded, were increased from 9 to 13% in low molecular weight fraction, compared to those of raw POL. Solubilization and degradation of polysaccharides were a directly propotional to specific mechanical energy in POL extrusion. WSP obtained by extrusion at Ext I and Ext II were found to be effective antioxidants in different in vitro assays with regards to 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC). However, these results suggest that WSP obtained using extrusion and subsequent enzymatic treatment may be an effective method to produce arabinogalactan from POL and be used as a functional food ingredients.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.12
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• pp.1848-1856
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• 2008

In order to enhance the functionality of a cotton fabric actually used as the clothing material for patients, the fabrics are treated with chitosan/nanosilver mixed solution. The nanosilver has excellent biocompatibility, not causing an environmental pollution as a natural polymer, provides expectation of an additional performance, does not harm human beings, and shows a strong antibacterial activity even in a small amount, and supplements chitosan, which is disadvantaged if used alone for fabric treatment. This study evaluates functional improvement of the clothing material for patients and observes through hygienic characteristics which are the most important function. In antibacterial activity of the fabrics treated with chitosan/nanosilver mixed solution against Staphylococcus aureus, higher ratio of chitosan was observed to achieve better antibacterial activity. In antibacterial activity against Klebsiella pneumoniae, higher ratio of nanosilver was observed to achieve better activity. Regarding laundry durability of antibacterial activity after repeated laundering, activity against Staphylococcus aureus was little reduced, but was greatly lowered against Klebsiella pneumoniae. Deodorization activity was excellent as the mixed ratio of chitosan was increased, and air permeability, moisture permeability and moisture regain were reduced as the mixed ratio of nanosilver was increased.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.12
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• pp.1873-1882
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• 2009

Hospital patient clothing material was treated with a mixture of chitosan in order to enhance functionality, such as the durability and dimensional stability of the cotton fabric used. Chitosan is a natural polymer with excellent biocompatibility, however there is a deteriorating adherence efficiency. The addition of a nanosilver colloidal solution in accordance with a prescribed ratio can further increase the performance of chitosan. Changes in the structural characteristics and physical properties of the chitosan/nanosilver treated fabric were observed in a comparison with fabric treated only with chitosan. The add-on ratio increased when the mixing ratio of nanosilver colloidal solution was higher; however, the crystalline structure of the treated fabric remains similar. In the case of CH3/NS1 treated fabric (where the mixing ratio of chitosan and nanosilver solution was 3:1) the K/S value, whiteness index, wet tensile strength, and wrinkle recovery angle were superior. The dimension stability, pilling resistance, and abrasion resistance of the fabric treated with a mixed solution increased in comparison to the fabric treated only with chitosan. The chitosan/nanosilver treated cotton fabric used for patient clothing material has excellent physical properties.

• Resources Recycling
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• v.29 no.6
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• pp.15-26
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• 2020

In recent years, there is an increasing interest in environmental friendly treatment of waste-plastics in terms of the generation of microplastics. Accordingly, the recycling of waste-plastics is very important because it provides advantages of volume reduction, mitigation of carbon dioxide emission, and reproduction of value-added products. In particular, in order to recycle the eco-friendly waste-plastics, it is necessary to use a physical separation methods, and among them, flotation separation, which can separate material (i.e., polymer component) in waste-plastics is well known as a very effective separation method in terms of material recycle. Therefore, in this review, the research trend of flotation separation for effective separation of mixture waste-plastics was investigated. In addition, through the reported research results, approaches to use as new functional materials from polymers, which are raw materials for waste-plastics, are summarized.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.346-347
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• 2012

최근 화석연료 대체 에너지원으로서 자동차용으로 연구 개발 및 응용되고 있는 고분자 전해질 연료전지(PEMFC: Proton exchange membrane fuel cells)에서 분리판(Bipolar Plate)은 스택 전체 무게의 80%, 스택 가격의 60% 정도로 가장 높은 비중을 차지한다. 분리판은 연료와 산화제를 공급해주는 통로 및 전지 운전 중에 생성된 물을 제거하는 통로 역할과 anode, cathode로서 전극 역할을 통해 스택 전력을 형성하는 핵심 기능과 전지와 전지 사이의 지지대 역할을 한다. 따라서 분리판은 전기전도성, 내부식성 및 기계적 특성이 우수해야함은 물론이고, 얇고 가벼우며 가공성이 뛰어나야 한다. 현재 가장 많이 사용되고 있는 금속 분리판 소재 중 스테인리스 스틸은 전기적, 기계적 특성 및 내부식성이 우수한 반면, 가격이 비싸고, 중량이 무거운 단점이 있다. 따라서 본 연구에서는 DC 반응성 마그네트론 스퍼터링법으로 전기적, 기계적 특성 및 내부 식성이 우수한 TiN, TiCN 박막을 스테인리스에 비해 중량이 1/3, 소재 단가가 1/4인 알루미늄 기판 위에 증착하여 박막 물성을 평가하였다. DC Power는 400 W, 기판과 타겟 사이의 거리는100 mm, 공정 압력은 0.5 Pa로 고정하였고, 3 inch의 지름과 순도 99.95%를 갖는 티타늄 타겟을 사용하였다. 공정 가스는 Ar을 주입하였으며, 질소와 탄소의 공급원으로는 질소($N_2$)와 메탄($CH_4$) 가스를 사용하여 챔버 내 주입혼합가스의 전체 유량을 50 sccm으로 고정시켰다. 증착된 박막의 전기적, 기계적 특성을 측정하였고, X-ray diffraction (XRD), Scanning electron microscope (SEM)을 이용하여 박막의 미세구조 및 표면 상태를 확인하였다. 또한, 내부식 특성을 평가하기 위해 potentiostatic, potentiodynamic 법을 이용하여 박막의 부식저항을 측정하였다. 증착된 TiN 박막의 경우 질소 함량의 증가에 따라 박막 증착속도는 감소하는 경향을 보였다. 이는 타겟 부근의 질소 라디칼 비율이 증가함에 따라 질화반응이 촉진된 것으로 생각된다. 또한, 증착된 TiN과 TiCN 박막은 반응성 질소 유량과 탄소 유량에 따라 각각 다른 미세구조를 가지는 것을 확인하였다. TiN과 TiCN은 NaCl형의 면심입방격자(FCC)로 같은 구조이며, 격자상수가 비슷하여 전율고용되어 TiCN을 형성하고, 탄소와 질소의 비에 따라 전기적 기계적 특성이 달라짐을 확인하였다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.1 s.55
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• pp.35-44
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• 2006

Recently, encapsulation studies have been tarried out to protect active agents using shell materials such as polymers, lipids, inorganic materials and the other protective materials. We have prepared copolymers of methylmethacrylate (MMA) and trimethoxysilylpropylmethacrylate (TMPMA), and the copolymers as shell materials were used for encapsulating active agents. Poly(MMA-co-TMPMA) spheres were very efficient for encapsulating active agents such as vitamin derivatives (such as retinol, retinyl palmitate, tocopheryl acetate and ascorbyl tetraisopalmitate) and oil soluble licorice extract etc. Mean diameters of poly(MMA-co-TMPMA) core-shell spheres containing active agents varied between about 0.1 to $10{\mu}m$ according to the experimental conditions. The loading amount of encapsulating active agents was 15 to 25% (w/w) and the loading yield was above 90%. The stability of active agents in poly(MMA-co-TMPMA) core-shell spheres prepared with an UV absorbing precursor increased by 25% compared with that of active agents in spheres prepared without an UV absorbing precursor.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.172.2-173
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• 2003

단백질, 탄수화물, 유지 등과 같은 생고분자를 소재로하여 제조하는 가식성 또는 생분해성 필름은 식품표면을 코팅하거나, 식품의 내부에 사용하여 식품을 외부의 충격으로부터 보호하고 식품의 저장수명을 증가시키는 동시에 수분, 기체 및 용질의 이동을 방지하는 기능을 한다. 이러한 가식성 필름의 소재 중 하나인 전분은 비교적 저가의 재료이고 기체투과를 방지하는 성질은 우수하지만, 탄력성이 적은 단점을 가지고 있다. 생고분자필름의 물리적 강도를 증진시키고 수증기의 투과성을 낮추는 방법으로 단백질과 탄수화물을 복합적으로 사용한다 본 실험에서는 분리 대두 단백질(SPI)과 옥수수 전분을 혼합하여 가식성의 생분해성 필름을 제조하고 이들의 이화학적 특성에 대해 연구하였다. SPI 필름은 SPI 5g에 증류수 100$m\ell$을 가해 glycerol 2g을 첨가해 제조하였으며, 옥수수 전분필름은 옥수수 전분 6g에 증류수 100$m\ell$을 가해 glycerol 1.2g을 첨가해 제조하였다. SPI와 옥수수 전분의 혼합필름은 SPI와 옥수수 전분의 양을 1：1 비율로 혼합하여 제조하였다. SPI 필름, 옥수수 전분 및 SPI와 옥수수 전분 용액의 혼합필름의 각각의 수증기 투과도는 7.49$\times$$10^{-11}$, 2.69$\times$$10^{-11}$, 4.24$\times$$10^{-11}$ g.m/m$^2$.s.Pa이었다. 본 실험으로 SPI의 단일재료로만 필름을 제조하였을 때보다 SPI 용액에 옥수수 전분용액을 혼합해 필름을 제조하면 탄력성을 유지하면서 수증기 투과도를 낮출 수 있다는 결과를 얻을 수 있었다.현미밥의 유리아미노산 분석 결과 필수아미노산을 포함한 다량의 아미노산이 존재하였으며 혈압강하 기능성 성분인 GABA(${\gamma}$ -amino butyric acid) 함량은 현미가 4.7 mg/100 g, 발아현미 20.8 mg/100 g이었으며, 동결건조 후 분석한 발아현미밥의 GABA 함량은 5.7 mg/100 g이었다. 발아현미밥의 관능검사 결과는 색, 윤기, 맛, 부착성, 응집성, 탄력성이 A가 유의적으로 높았으며, 외관의 경우도 A가 더 높은 평가를 받았다. 또한 전반적으로 A가 B에 비해 유의적인 차이를 나타내진 않았지만 더 나은 선호도를 나타내었다.좋게 평가되었다.＊값은 63-68사이로, a＊값은 0.13에서 -0.89사이를 b＊값은 2-5값 사이에서 변화하여 제조한 죽의 색이 옅은 황색임을 알 수 있었다. 고형분 함량, 퍼짐성과 pH에 대한 $R^2$은 각각 0.4280, 0.5433과 0.2406임을 볼 때 버섯, 당근, 대파의 비율에 따라 제조한 쇠고기 야채 쌀죽의 고형분 함량, 퍼짐성과 pH는 설정된 범위내에서 그 유의성이 인정되지 않아 큰 영향을 미치지 않음을 알 수 있었다. 관능검사 결과, 색과 향에 대한 반응표면 회귀식의 $R^2$은 각각0.6000과 0.7825이고 P-value는 각각 0.4290과 0.0942로서 5% 수준에서 유의한 상관성이 없음을 확인할 수 있었다. 맛과 점성에 대한 $R^2$은 0.8717과 0.8068이고 P-value는 각각 0.0195 (p ＜0.05)와 0.0612로서 야채의 배합비에 따라 맛에 있어서 유의확률 5%수준에서 그 유의성이 인정되었으며, 전체적인 기호도에 대한 유의성은 $R^2$이 0.8463이고 P-value는 0.034