• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.709-716
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• 2015

In this study, structural developments of polypropylene / ionomer / clay ternary composites were investigated depending on the dispersion and localization of clay. The changes in physical properties were observed adding organoclays 1~10wt% to 90% polypropylene and 10% ionomer blends. The organoclays were localized inside of the dispersed phase under the composition of 3wt%, however, over that composition, clay particles formed stiff network structure in the dispersed phase and additional clays were localized at the interface between two phases. According to the developments of microstructure, the interaction of ternary composites changed from polypropylene-ionomer to polypropylene-ionomer and ionomer-clay which affected rheological properties. The storage modulus (G') of the composites was similar to the blends when clays were localized inside of dispersed phase but increased when clays were localized at interface. Also, the fractured morphology of the composites showed phase boundary and growing radius of dispersed phase depending on addition of fillers when clays were found inside. However, when fillers found at the interface between blends, the radius of the dispersed phase decreased and compatibilized morphology were observed. The interfacial interaction of the ternary composite was quantified depending on the structural development of dispersed phase and localization of clay particles by the rheological properties. The interaction of composites at solid state which was measured through peel adhesion strength increased by growth of interfacial interaction of each component. Furthermore, the crystallinity of the composites was decreased when the clay particles were localized at the interface.

• Composites Research
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• v.32 no.2
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• pp.96-101
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• 2019

Interfacial adhesion between fiber and resin are related to composites performance, so it is very important to evaluate them accurately. In this study, the interfacial properties of microdroplets under fatigue loading conditions were evaluated. The mechanical properties and interfacial adhesion of epoxy resin with dopamine were studied. Tensile specimens were prepared to evaluate mechanical properties and epoxy microdroplets specimens were used for the evaluation of interfacial adhesion. In addition, in the microdroplet fatigue test, the same diameter of the microdroplet was used and the experiment was performed under the same conditions. As a result, it was confirmed that mechanical and interfacial properties were improved when dopamine was applied to epoxy resin through tensile and microdroplet experiments. It is considered that dopamine improves the degree of curing of the epoxy resin and imparts hydroxyl groups to the epoxy resin to increase the mechanical properties and the interfacial adhesion between the glass fibers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.289-294
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• 2017

Films fabricated using atomic layer 2-dimensional nanosheets exhibit various physical properties depending on the size of the nanosheet. This is because the physical properties of the film depend on the interfacial properties between the sheets. Therefore, the synthesis of large-sized nanosheets is very important because it can reduce the dependency of the film on the interfacial properties. In this study, we succeeded in fabricating $TiO_x$ nanosheets with atomic layer thickness over micrometer size by using single-crystallized starting material and its chemical exfoliation. In addition, it was revealed that the mechanical agitation speed (the stirring speed of a magnetic bar) during the exfoliation step using the organic material is closely related to the nanosheet size and the colloidal concentration of the nanosheets.

• Journal of Adhesion and Interface
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• v.8 no.3
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• pp.9-15
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• 2007

The interfacial evaluation of surface modified Jute fiber/polypropylene (PP) composites before and after hydration was investigated using micromechanical test and dynamic contact angle measurement. The IFSS of alkaline and silane-treated Jute fiber/PP composites increased, whereas after hydration, the IFSS of the untreated, alkaline- and silane-treated Jute fibers/PP composites decreased due to swelled fibrils by water infiltration. The interfacial adhesion of silane treated fiber/PP composites was higher than alkaline-treated or the untreated cases. The surface energies of Jute fiber treated under various conditions were obtained using dynamic contact angle measurement. Especially after hydration, the thermodynamic work of adhesion was calculated by considering water interlayer, which indicated the stability of IFSS between silane treated Jute fiber and PP matrix showing better than others.

• Elastomers and Composites
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• v.37 no.2
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• pp.99-106
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• 2002

In this work, the surface properties and mechanical interfacial properties of the carbon blacks treated by oxygen plasma were investigated. The surface properties of carbon black by oxidation process of oxygen plasma were studied in acid-base surface value, zeta potential, and X-ray photoelectron spectroscopy (XPS). And their mechanical interfacial properties of the carbon black/rubber composites were evaluated by the composite tearing energy ($G_{III}c$). As a result, it was found that the introduction rate of oxygen-containing polar functional groups, such as carboxyl, hydroxyl, lactone, and carbonyl groups, onto the carbon black surfaces was increased by increasing the plasma treatment time. It revealed that the polar rubber, such as acrylonitrile butadiene rubber (NBR), showed relatively a high degree of interaction with oxygen-containing functional groups of the carbon black surfaces, resulting in improving the tearing energy ($G_{III}c$) of the carbon black/acrlyonitrile butadiene rubber composites.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.44-48
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• 1999

섬유 강화 고분자 복합재료에서 강화재인 섬유와 매트릭스의 계면은 복합재료의 물성에 지대한 영향을 미친다. 섬유와 매트릭스의 물성 차이 즉, 탄성율, 열팽창 계수, 경화시의 수축, 결정화도 등의 차이뿐만 아니라 하중이 가해질 때 응력 집중 (stress concentration) 현상이 계면에서 일어난다[1]. 유리섬유를 강화재로 사용한 복합재료에서 유리섬유는 표면이 hydroxyl기로 덮여 있기 때문에 친수성이 매우 크고 또한 마찰이나 정전기에 의해 손상을 받기 쉬운 단점이 있다. 따라서 매트릭스 수지와의 계면 접착력을 향상시키고 제조 공정 중에 섬유를 마찰이나 정전기로부터 보호하기 위한 처리가 필요하며 이들 "sizing" 이라고 한다[2,3].고 한다[2,3].

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.503-503
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• 2011

알루미늄 도금강판은 Al-10%Si의 Type 1과 100%Al의 Type2로 구분되어 진다. 그러나, 국내에서는 Type1만이 생산되고 있으며, Zn이 주요성분이 되는 도금강판대비 내열성이 우수하여, 고온기기나 자동차용 배기계 등에 상용되고 있다. 이러한 알루미늄 도금강판의 특성은 표면조직이나, 소재에 도금층과 반응하여 형성된 계면합금층의 특성에 따라, 내열성, 가공성, 내식성 등의 물성에 큰 영향을 미친다. 특히, 합금층은 매우 취성이 강하여 도금층의 박리 등을 유발할수 있으며, 고온에서는 합금층이 성장하여, 내열성 등 물성에 영향을 미친다. 그러나, 이러한 합금층의 결정구조나 조직에 대해서도 연구자간의 분석결과가 일치하지 않으며, 합금층의 고온에서의 거동에 대해서도 잘 이해되지 않고 있다. 본 연구에서는 이러한 합금층에 대한 문헌조사 및 내열실험을 통하여 합금층거동을 분석하고자 하였으며, 또한, 이상적인 도금구조를 갖는 건식도금 샘플을 제작하여 합금층의 내열특성을 상호 비교하였다. 본 발표에서는 이러한 결과를 제시한고자 한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.295-295
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• 2012

본 연구에서는 아크방전을 이용한 질화 티타늄의 합성 과정 중에서, 시편 청정 공정변수를 변화시킴에 따라 계면에서의 미세조직 변화와 코팅층의 물성을 평가하였다. 아크 소스에 장착된 타겟은 $120mm{\Phi}$, 99.5 %의 티타늄 타겟을 사용 하였고, 시편과 타겟 간의 거리는 약 30 cm이며, 시편은 SUS를 사용하였다. 시편을 진공용기에 장착하고 진공배기를 실시한 후 Ar 가스 분위기에서 시편에 전압을 인가한 후 아크를 발생시켜 약 5분간 시편 청정을 실시하였다. 이 시편 청정 과정에서 시편 인가전압을 0~1,000 V로 변화시켰고 시편 정청이 끝나면 시편에 인가된 전압을 차단하고 코팅하였다. 질화 티타늄의 두께는 약 $3{\mu}m$로 동일하게 코팅하였다. 시편 인가전압 변화에 따라 시편청정 공정 시 계면에서 티타늄층이 코팅되거나 모재 내부까지 침투하는 현상을 관찰하였다. 시편청정 공정변수 변화에 따른 질화 티타늄의 코팅을 통해 계면의 미세조직과 성분의 변화를 주사전자현미경, 투과전자현미경 이미지와 에너지 분산분광기 (Energy Dispersive Spectroscopy ; EDS)를 통해 확인하였으며 나노인덴터를 이용해 경도, 탄성계수 등의 물성변화를 측정하였다. 본 연구에서 얻어진 결과를 이용하여 시편 청정 공정 제어를 통한 다양한 물성변화가 가능 할 것으로 예상된다.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.579-586
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• 2018

In this study, surfactants were synthesized using fatty alcohols of 8, 10, 12 and 14 carbon chains length. The structures of the synthesized surfactants was confirmed by FT-IR and $^1H$-NMR analysis. The surface tension of the diluted surfactant was measured as 26~32 mN/m depending on the carbon length and the critical micelle concentration was measured as $10^{-3}{\sim}10^{-5}mol/L$.The minimum value per molecule of the synthesized sulfonic acid surfactant is 1.68 to $1.30nm^2$. The physical properties of the synthesized surfactants were determined by measuring the critical micelle concentration, foaming power, emulsifying stability, and contact angle.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.102-107
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• 2019

Anionic surfactants were synthesized by using an sarcosine, taurine and fatty alcohol with varying the carbon chain length. The structure of synthesized surfactants was confirmed by $^1H$ NMR analysis. The critical micelle concentration of the synthetic anionic surfactant was $10^{-2}{\sim}10^{-4}mol/L$ and the surface tension value at the critical micelle concentration was between 21 and 39 mN/m. It was confirmed by the Ross-Miles method that the synthetic surfactant with the carbon chain of 12 showed a good foaming power and stability. In addition, the surfactant using the sacosine was found to have a good affinity in soybean oil while that using taurine in benzene. The physical properties of synthesized surfactants were determined by measuring the critical micelle concentration, foaming power and emulsifying stability.