• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.524-532
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• 2018

In this study, two types of amino acids-based anionic biosurfactants such as potassium cocoyl glutamate (CTK) and sodium cocoyl glutamate (CTN) were synthesized from coconut oils and the structure elucidation of CTK and CTN was carried out by using FT-IR, $^1H-NMR$ and $^{13}C-NMR$ spectrophotometries. Measurements of interfacial properties such as static and dynamic surface tensions and emulsification activity showed that both CTK and CTN were surface-active and effective in lowering the interfacial free energy. In particular, the CTK surfactant was found to be more efficient in reducing the interfacial free energy since the larger number of CTK molecules was preferentially adsorbed at the air-water interface due to the higher hydrophobicity and larger mobility of CTK than those of using CTN, indicating possible uses in cosmetics and household products formulation.

• Korean Journal of Materials Research
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• v.8 no.1
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• pp.13-18
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• 1998

SMC(Sheet molding compound)욕조 생산시 발생하는 폐 FRP를 보강재로서 재활용하기 위하여 불포화 폴리에스테르 매트릭스 수지에 보강하고 보강재와 매트릭스 수지의 계면 결합력을 증진시키기 위하여 보강재를 실란계 커플링제[3-methylacryloxyviny1 silane (MAOS)]로 전 처리하여 복합재를 제조하고 기계적 물성 및 계면현사에 대하여 관찰하였다. 보강률이 20wt%인 복합재의 굴곡강도 및 굴곡탄성률이 각 각 110MPa, 8.0GPa로 가장 우수하였으며 커플링제(MAOS)의 노동가 0.50wt%인 복합재의 굴곡강도 및 굴곡탄성률은 약 10%정도 향상되어 각 각 120MPa, 9.2GPa을 나타내었다. 또한 주사전자현미경 관찰 결과 보강재를 커플링제(MAOS)로 처리한 복합재의 보강재와 매트릭스 수지는 물리, 화학적을 잘 결합하여 보강재와 매트릭스 수지의 계면에서 pull out현상이 확인되지 않았으며 크랙도 발생하지 않았다.

• Polymer(Korea)
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• v.29 no.3
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• pp.221-230
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• 2005

Interfacial interactions and interphases played a key role in multicomponent materials irrespectively of the number and type of their components or their actual structure. They were equally important in particulate filled polymer, polymer blends, fibers-reinforced advanced composites, nanocomposites or biomimetic materials. Recognition of the role of the main factors influencing interfacial adhesion and proper surface modification could lead to significant progress in many fields of research and development, as well as in related technologies. Although the role and importance of interfaces and interphases were the same for all multicomponent materials, the surface modification could be always selected according to the objectives targeted, as well as to the characteristics of the particular system. In this wort therefore, several types of surface modification were performed to improve the interfacial interactions between two components in composite system and their results for the composites were investigated.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.476-482
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• 2013

In this work, the effects of electrochemical oxidation of carbon fiber surfaces on mechanical interfacial properties of carbon fibers-reinforced polarized-polypropylene matrix composites were studied with various current densities during the treatments. Surface properties of the fibers before and after treatments were observed by SEM, AFM, XPS, and contact angle measurements. Mechanical interfacial properties of the composites were measured in terms of critical stress intensity factor ($K_{IC}$). From the results it was found that $O_{1s}$ peaks of the fiber surfaces were strengthened after electrochemical oxidation which led to the enhancement of surface free energy of the fiber, resulting in good mechanical performance of the composites. It can be concluded that electrochemical oxidation of the carbon fiber surfaces can control the interfacial adhesion between the carbon fibers and polarized-polypropylene in this composites system.

• Composites Research
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• v.16 no.2
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• pp.62-67
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• 2003

Interfacial properties and damage sensing for the carbon fiber/epoxy-amine terminated (AT)-polyetherimide (PEI) composite were performed using microdroplet test and electrical resistance measurements. As AT-PEI content increased, the fracture toughness of epoxy-AT-PEI matrix increased, and interfacial shear strength (IFSS) increased due to the improved fracture toughness by energy absorption mechanisms of AT-PEI phase. The microdroplet in the carbon fiber/neat epoxy composite showed brittle microfailure mode. At 15 phr AT-PEI content ductile microfailure mode appeared because of improved fracture toughness. After curing, the change in electrical resistance $\Delta\textrm{R}$) with increasing AT-PEI content increased gradually because of thermal shrinkage. Under cyclic stress, in the neat epoxy case the reaching time until same stress was faster and their slope was higher than those of 15 phr AT-PEI. The result obtained from electrical resistance measurements under curing process and reversible stress/strain was correspondence well with matrix toughness properties.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.791-796
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• 2013

In this study, the mechanical properties of a carbon fiber/polypropylene composite were evaluated according to the carbon fiber surface treatment. Carbon fiber surface treatments such as silane coupling agents and plasma treatment were performed to enhance the interfacial strength between carbon fibers and polypropylene. The treated carbon fiber surface was characterized by XPS, SEM, and single-filament tensile test. The interlaminar shear strength (ILSS) of the composite with respect to the surface treatment was determined by a short beam shear test. The test results showed that the ILSS of the plasma-treated specimen increased with the treatment time. The ILSS of the specimen treated with a silane coupling agent after plasma treatment increased by 48.7% compared to that of the untreated specimen.

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.312-319
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• 2013

This study is to do with the synthesis of glycidyl succinate cationic gemini surfactant. The gemini surfactant was synthesized with using 2-methyl disodium succinate, epichlorohydrine and N,N-dimethyl dodecyl amine. The target material was confirmed by FT-IR, $^1H$-NMR and was tested their properties. Surface active properties such as surface tension, evaluated cmc, emulsing properties, foaming properties were measured respectively at given conditions. The surface tensions for the aqueous solution of gemini surfactant were 33~34 dyne/cm and their cmc values evaluated by surface tension method were $10^{-4}{\sim}10^{-3}mol/L$. Emulsing properties of gemini surfactant was better in organic solvent and foaming power was confirmed good stability.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.85.1-85.1
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• 2016

현대 과학기술에는 표면/계면 및 나노물질의 구조와 물성을 분석하는 다양한 방법들이 존재한다. 이들 분석장비들의 분해능과 감도의 향상으로 이전에는 보지 못한 물성들이 속속 발견되고 있다. 이러한 흐름 속에서 분석장비들의 다기능 시대가 열리고 있다. 예전에는 성분, 형태, 구조, 전자구조 등을 분석하기 위해 각각에 해당하는 분석장비들이 동원되었다. 하지만 21세기에 접어들어 분석장비들이 두 종류 이상의 분석이 가능하도록 개발되었다. 예를 들면, TEM으로 형태를 보는 것 외에도 TED와 EELS로 구조와 성분을 동시에 확인할 수 있게 되었다. 전통적인 성분 및 전자구조 분석법의 하나인 광전자분광법도 microscopy 기능을 탑재하는 변신이 있었다. 본 발표에서는 빛과 전자를 시료에 조사하여 물질의 성분, 형태, 구조, 전자구조 등을 동시에 분석이 가능한 분석법들에 대해 소개하고자 한다. 그 중, SPEM(Scanning Photoelectron Emission Microscopy)은 포항가속기연구소에 설치되어 있으며, PEEM(Photoelectron Microscopy)과 LEEM(Low Energy Electron Microscopy)은 수차보정장치를 갖춘 사양으로 최근 한국기초과학지원연구원에 설치되었다. 위에 언급한 장비를 활용하여 얻은 데이터를 바탕으로 나노물질의 표면 및 계면의 특성을 분석하는 방법 및 최근 연구 결과를 소개하고자 한다.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.6
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• pp.1-8
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• 1992

본 고에서는 균질화법의 정식화를 이용하여 복합재료의 거시적 균질화된 재료상수를 구하고, 이 재료상수를 이용하여 거시구조물의 변형과 응력을 구하고, 이로부터 다시 미시구조의 응력분포와 변형도를 구하는 방법을 기술하였다. 주기성을 가정한 균질화법은 복합재료 구조물의 물성평가와 거동예측에 대한 매우 적절한 수치해석 방법이다. 균질화법은 이러한 선형변형의 문제뿐만 아니라, 내압을 존재하는 빈공간 소재의 물성, 기지재료와 강화재료 계면의 미끄러짐 등으로 인한 미세 파손현상 등의 예측이 가능하다. 그외에도 탄소성 대변형 거동 이론과 균질화법을 함께 적용하여, squeeze casting에서 발생하기 쉬운 계면분리나 파단 등의 미소결함과 같은 2차 성형성의 예측도 가능하다.

• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.45-52
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• 2002

기존의 점착제 합성방법에서 탈피하여 용액형 점착제(Solution)의 장점과 입자형 점착제(Emulsion)의 장점을 동시에 보유한 NAD (Non-Aqueous Dispersion Polymer)를 합성하였다. NAD는 메탄올 분위기에서 6개월 이상의 분산 안정성을 유지하였다. NAD는 용액에서 입자형 고분자의 형태를 이루고 있음을 도공 공정에서 확인하였다. 또한 기존의 아크릴 점착제의 장점과 고무계점착제의 장점을 결합한 고분자량의 점착제, GP (Graft Polymer)를 합성하였다. GP는 자체가 매우 높은 분자량을 보유하여 가교제의 첨가 없이도 우수한 물성을 나타내었다. GP는 일반적으로 고 분자량의 고분자에서 나타나는 Weissenberg effect 현상을 나타내었다. 이들의 점착제로 응용시 각각의 물성을 비교하여 나타내었다.