• Journal of Adhesion and Interface
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• v.13 no.2
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• pp.58-63
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• 2012

CFRP chip is the byproduct from carbon fiber reinforced plastic (CFRP) processing. CFRP chip is not simply a waste mainly composed of fine carbon fiber and epoxy resin. CFRP chip keeps matrix to maximize their reinforcing effect. To obtain a uniform length of carbon fiber in CFRP chip, chip was chopped ina mortar. CFRP chip should be purified to get better interface adhesion. Epoxy resin on the carbon fiber was removed by $H_2O_2$ surface etching treatment. Optimal dispersion and fabrication conditions of CFRP chip embedded in phenolic resin were determined by thermal stability for fire retardant applications. CFRP chip-phenolic composite exhibits better mechanical and thermal properties than neat phenolic resin. Surface condition of CFRP chip-phenolic composite was evaluated by static contact angle measurement. Contact angle of CFRP chip-phenolic composite was greater than neat phenolic due to heterogeneous condition of fine carbon fibers. From the evaluation for fire retardant (ASTM D635-06) test, thermal stability of CFRP chip-phenolic composite was found to be improved with higher concentration of CFRP chip.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.49-56
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• 2012

Rupture disks are a kind of safety device in high pressure equipment and they are used to control rupture pressure in the solid rocket motor. In this paper, a series of rupture experiments was performed using rupture disks made of AISI 316L and rupture pressure of rupture disks was calculated through various assumptions in relation between elasto-plastic material properties and true stress-strain curve. Experiment and FEA indicated rupture pressure is determined by size of rupture disks. As a result of elasto-plastic analysis, only multi-linear stress-strain curve was able to calculate meaningful estimations. Experimental results also showed rupture location are decided by the size of rupture disks. Experimental and FEA results will be applied to control rupture pressure of disks.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.1
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• pp.89-94
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• 2014

The high Young's modulus and tensile strength of carbon nanotubes has attracted great attention from the research community given the potential for developing super-strong, super-stiff composites with carbon nanotube reinforcements. Over the decades, the strength and stiffness of carbon nanotube-reinforced polymer nanocomposites have been researched extensively. However, unfortunately, such strong composite materials have not been developed yet. It has been reported that the efficiency of load transfer in such systems is critically dependent on the quality of adhesion between the nanotubes and the polymer chains. In addition, the waviness and orientation of the nanotubes embedded in a matrix reduce the reinforcement effectiveness. In this study, we carried out performed micromechanics-based numerical modeling and analysis by varying the geometry of carbon nanotubes including their aspect ratio, orientation, and waviness. The results of this analysis allow for a better understanding of the load transfer capabilities of carbon nanotube-reinforced polymer composites.

• Composites Research
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• v.24 no.6
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• pp.1-6
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• 2011

A new water-soluble and self-doped poly(styrenesulfonic acid-graft-aniline), PSSA-g-PANI, for dispersing carbon nanotubes (CNTs) in water was synthesized and its ability to stabilize aqueous CNT dispersions was examined. It was observed that the PANI in PSSA-g-PANI, which has benzoid and quinoid structure, was strongly adsorbed onto the nanotube surface via a strong ${\pi}-{\pi}$ interaction, and thus only gentle sonication causes exfoliation of CNT ropes to small bundles and the long-term stability of their resulting dispersions was much better than commercial surfactants. Furthermore, when thin films of PSSA-g-PANI/CNT are prepared from aqueous dispersion and their electrical conductivities are measured by the four probe technique, it is observed that their conductivities are in the range of 1.5-2.5 S/cm.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.170-174
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• 2008

We have studied, using Raman and photoluminescence (PL) spectroscopy, material property changes of single-walled carbon nanotubes (SWCNTs) dispersed in sodium dodecyl sulfate(SDS) aqueous solution by ultrasonication. Radial breathing mode Raman intensities of the dispersed SWCNTs shows different behavior depending on their chiralities as the sonication time increases. As the amount of SWCNTs dispersed in 1wt% SDS solution increases, both a downshift of the G-band Raman frequency and an enhancement in the PL intensity were observed.

• Membrane Journal
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• v.23 no.5
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• pp.375-383
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• 2013

Nanomaterials having large surface area, uniform dimensions or pores can be utilized in various membrane applications Amongst them, many studies have been focused on nanocarbon materials: graphene, graphene oxide and carbon nanotubes. Carbon nanotubes, one-dimensional structure, have excellent characteristics in thermal, chemical and mechanical strength properties. However, carbon nanotubes was mainly used to reinforce mechanical properties of polymer materials in previous applications. In contrast to previous studies, we focused on modified carbon nanotubes/polyethylene glycol diacrylate (PEGDA) composite membrane preparation for improvement of permeability and selectivity on gas separation.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.363-369
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• 2016

Enhancing mechanical strength of concrete has been fascinated using carbon-based nanomaterials such as CNT and graphene. The key to improving strength is a dispersion of nanomaterials. A novel method is required to investigate the dispersion inner concrete nondestructively. In this study, the optical optical properties such as refractive index and absorption coefficient are measured in nano-cement mortar specimens containing MWCNT and GO using THz electro-magnetic waves. From the results, the properties of nano-cement mortar are confirmed to be 1.0% to 2.5% higher in refractive index, and -14% to 28% higher in absorption coefficient than those of cement mortar at the average values. Using these characteristics, visualizing the dispersion of nano-concrete structures seems possible in future.

• Composites Research
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• v.33 no.3
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• pp.91-100
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• 2020

Polyphenylene sulfide (PPS) is a semi-crystalline engineering thermoplastic resin that has outstanding thermal stability, mechanical strength, inherent flame retardancy, chemical resistance, and electrical properties. Due to these outstanding properties, it is preferred as a matrix for composite materials. Many studies have been conducted to produce composites with carbon fibers and glass fibers to improve mechanical properties and provide functionality of PPS. In this review paper, we report a brief introduction to the fabrication and applications of PPS composites with carbon nanotubes, graphene, carbon fibers, and glass fibers.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.77-77
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• 2010

그래핀(Graphene)은 한 겹(layer)의 2차원 판상 구조에 탄소원자들이 육각형의 기본 형태로 배열되어 있는 나노재료로서, 우수한 역학적 강도와 화학적, 열적 안정성 및 흥미로운 전기 전자적 성질을 가지고 있는 것으로 알려져 있다. 최근, 이러한 특징적이고도 우수한 물성으로 인하여 기초물성 연구에서부터 차세대 응용까지 고려한 각종 연구들이 활발하게 진행되고 있다. 일반적으로 그래핀을 얻는 방법에는 물리 화학적 박리, 열화학증기증착법(TCVD), 탄화규소의 흑연화, 흑연산화물의 환원 등의 방법들이 알려져 있다. 그 중 TCVD법이 두께의 균일성이 높은 그래핀을 합성하는데 가장 적절한 것으로 알려져 있다. 그러나 TCVD법은 탄소를 포함하는 원료가스를 분해하기 위하여 고온의 공정을 필요로 하게 되지만, 향후 산업적 응용을 고려한다면 대면적 그래핀의 저온합성법 개발은 풀어야 할 시급한 과제로 인식되고 있다. 현재는 메탄을 원료가스로 사용하여 $900^{\circ}C$ 이상에서 그래핀을 합성하는 추세이고, 최근 아세틸렌등의 활성원료가스를 이용하여 $900^{\circ}C$ 이하에서 저온 합성한 연구결과들도 속속 보고되고 있다. 본 연구에서는 고주파 플라즈마를 이용하여 비교적 저온에서 탄소원료가스를 효율적으로 분해하고, 확산플라즈마 영역에 TCVD 챔버를 결합한 하이브리드 화학증기증착법을 이용하여 그래핀의 저온합성을 도모하였다. 원료가스로는 메탄을 사용하였고, 기판으로는 전자빔증착법으로 증착한 니켈 박막 및 구리포일을 사용하였다. 실험결과, 그래핀은 $600^{\circ}C$ 부근의 저온에서도 수 층으로 이루어진 그래핀이 합성된 것을 확인하였다. 합성한 그래핀은 분석의 용이함 및 향후 다양한 응용을 위하여 실리콘산화막 및 투명고분자 기판 위에 전사(transfer)하였다. 합성된 그래핀의 구조평가를 위해서는 광학현미경과 Raman분광기를 주로 사용하였으며, 원자힘현미경(AFM), 주사전자현미경(SEM), 투과전자현미경(TEM) 등도 이용하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.183.2-183.2
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• 2013

저항이 낮고 투과도가 일정한 투명전도막(TCF)의 내구성을 향상 및 유지 시키는 연구는 상업화에 가장 필요한 연구 분야이다. 그 중 탄소나노튜브(CNT)와 실버나노와이어(AgNW)를 섞어 만든 CNT-AgNW는 우수한 광투과성과 내화학성 및 균일한 전기 전도성을 갖고 있고 그 기반의 투명전도막은 기존의 ITO 및 CNT 박막보다 우수한 유연성을 갖기 때문에 차세대 플렉시블 디스플레이 소재로서 많은 관심을 모으고 있다. 본 연구는 PET를 이용한 CNT-AgNW로 제작된 투명전도막 위에 물성 및 두께 따른 하드오버 코팅을 통한 내구성 개선 및 유지를 연구하였다. 하드오버 코팅 물질로는 실로콘계 하이브리드 투명 하드코팅 소재를 기본으로 하고 용매 및 용질의 합성 온도를 제어하고 코팅막의 두께(Thin, Thick)를 조절을 통해 내구성 개선을 증진시키려 하였다. 연구결과 물성 향상에 가장 많은 영향을 끼치는 것은 CNT-AgNW 코팅층과 하드오버 코팅층과의 젖음성으로, 그 젖음성이 증가할수록 투과도 및 전기전도도가 향상되는 것을 관찰하였다. 분석 결과, 용매의 비점 및 비중, 용질의 합성 온도가 하드오버코팅 젖음성에 가장 많은 영향을 주는 것을 확인하였다. 또한 항온 항습($85^{\circ}C/85%$) 환경에서 240시간 이상 내구성 테스트 결과 하드오버코팅 물질 중 고온합성 및 고비점 용매를 이용하고 thick 조건이 Thin조건보다 투명전도성 평가 지수(${\sigma}DC/{\sigma}OP$)가 향상 되었다. 또한 Thin에서 면저항(${\Omega}/{\square}$) 변화율이 10% 이상을 보인 반면, Thick에서는 10% 이내의 변화율 유지를 확인하였다.