• Carbon letters
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• 제14권1호
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• pp.58-61
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• 2013

In this work, the effect of catalysts on the mechanical properties of carbon fibers-reinforced epoxy matrix composites cured by cationic latent thermal catalysts, i.e., N-benzylpyrazinium hexafluoroantimonate (BPH) was studied. Differential scanning calorimetry was executed for thermal characterization of the epoxy matrix system. Mechanical interfacial properties of the composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor ($K_{IC}$), and specific fracture energy ($G_{IC}$). As a result, the conversion of neat epoxy matrix cured by BPH was higher than that of one cured by diaminodiphenyl methane (DDM). The ILSS, $K_{IC}$, $G_{IC}$, and impact strength of the composites cured by BPH were also superior to those of the composites cured by DDM. This was probably the consequence of the effect of the substituted benzene group of BPH catalyst, resulting in an increase in the cross-link density and structural stability of the composites studied.

• Carbon letters
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• 제12권1호
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• pp.53-56
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• 2011

This study aimed to investigate the influence of mesoporous carbons on the thermal insulation properties of epoxy/mesoporous carbon composites. The mesoporous carbon (CMK-3) was prepared by conventional templating method using SBA-15. The epoxy/mesoporous carbon composites were prepared by mixing the synthesized CMK-3 with diglycidylether of bisphenol A (DGEBA). As experimental results, the curing reactivities of the DGEBA/CMK-3 composites were found to decrease with the addition of the CMK-3. Also, the thermal conductivities of DGEBA/CMK-3 composites were found to decrease with increasing CMK-3 content. This could be interpreted in terms of the slow thermal diffusion rate resulting in pore volume existing in the gaps in the interfaces between the mesoporous carbon and the DGEBA matrix.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.111-115
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• 2005

Recently, natural fibers draw much interests in composite industry due to low cost, light weight, and environment-friendly characteristics compared with glass fibers. In this study, mechanical properties were evaluated for two extreme cases of jute fiber orientations, i.e. the unidirectional yarn composites and the felt fabric composites. Samples of jute fiber composites were fabricated by RTM process using epoxy resin, and tensile, compression, and shear tests were conducted. As can be expected, unidirectional fiber specimens in longitudinal direction showed the highest strength and modulus. Compared with glass/epoxy composites of the similar fabric architecture and fiber volume fraction, the tensile strength and modulus of jute felt/epoxy composites reached only 40% and 50% levels. However, the specific tensile strength and modulus increased to 80% and 90% of the glass/epoxy composites. The main reason for the poor mechanical properties of jute composites is associated with the weak interfacial bonding between fiber and matrix. The effect of surface treatment of jute fibers on the interfacial bonding will be examined in the future work.

• 한국해양공학회지
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• 제28권1호
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• pp.64-68
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• 2014

This study was conducted to investigate the durability of carbon fiber/epoxy composites (CFRP) in a saline water environment. The carbon fiber/epoxy composites were modified to use nanoparticles such as carbon nanotubes and titanum oxide. These hybrid composites were exposed to a saline water environment for a certain period. The weight gain according to the immersion time, a quasi-static tensile test, and micro-graphic characterization were used to investigate the samples exposed to the saline water environment. The weight gains increased with increasing immersion time. The weight gains of the hybrid composites were lower than that for pure CFRP throughout the entire immersion time. The tensile strengths decreased with increasing immersion time. The tensile strengths of the hybrid composites were higher than that of the pure CFRP throughout the entire immersion time. The pure CFRP was observed to be more degraded than the hybrid composites in the saline water environment. Therefore, it was concluded that the addition of nanoparticles to CFRP could lead to improved durability in a saline water environment.

• 폴리머
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• 제38권6호
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• pp.782-786
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• 2014

세라믹 방열 복합체의 특성 비교를 위해 casting method로 제작하였으며, 이들의 광학적 이미지와 단면 FE-SEM 분석을 실시하였다. 각각의 복합체의 열전도성 특성을 비교 분석하였으며, silicon carbide(SiC)의 분산도 문제를 해결하기 위해 wetting process를 도입하여 SiC/epoxy 복합체를 제작하였다. 기존의 방법에서 발견된 복합체 내공극과 분산도 문제가 wetting process를 통해 향상되었으며, 충전제 함량에 따른 열전도성 특성을 분석하였다. SiC 복합체의 함량에 따른 공극률 해석을 통해 70 wt% SiC 복합체에서 가장 높은 열전도도 값을 보였으며, 이들의 단면 FE-SEM 분석을 통해 복합체 내의 충전제 분산도를 확인하였다.

• Advanced Composite Materials
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• 제17권4호
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• pp.333-341
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• 2008

A novel manufacturing method for hybrid composites filled with carbon nanotubes (CNTs) and aramid fibers is proposed. To disperse the CNTs in the epoxy matrix with the presence of aramid fibers, CNT/polyethyleneoxide (PEO) composites are prepared and utilized because PEO is miscible in the epoxy resin. After thin films are made of the CNT/PEO composite and placed together with the aramid fibers, the epoxy resin is infused to them. The PEO is dissolved in the epoxy and then the CNTs are dispersed in the PEO/epoxy matrix between aramid fibers before the pre-heated matrix is cured. It is found that the PEO is completely miscible with the epoxy resin and CNTs are dispersed well in the space between the aramid fibers.

• 동력기계공학회지
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• 제18권6호
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• pp.174-179
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• 2014

The wear behavior of epoxy matrix composites filled with nano sized silica particles is discussed in this paper. Especially, the variation of the coefficient of friction and the specific wear rate under the various applied load and sliding velocity were investigated for these materials. Wear tests of pin-on-disc mode were carried out and followed by scanning electron microscope observations. The presence of silica filler in epoxy composites was demonstrated significant influence on the friction and wear behavior of epoxy nanocomposites. With the incorporation of silica filler into the epoxy matrix, reduction of the coefficient of friction and specific wear rate were identified. Wear mechanism was discussed by analyzing the worn surface by scanning electron microscope as well.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.52-55
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• 2002

This paper examines the effective thermal conductivity of 3-D braided glass/epoxy composites. 3-D braided composites have a number of advantage over conventional laminate composites, including through-thickness reinforcement, and high damage tolerance and processability. The thermal properties of composites depend primarily on the microstructure of the braided preform and properties of constituent materials. A thermal resistance network model based on structure of the braided preform is proposed by using thermal-electrical analogy. In order to affirm the applicability theses solutions, thermal conductivities of 3-D braided glass/epoxy composites are measured

• Structural Engineering and Mechanics
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• 제64권3호
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• pp.287-292
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• 2017

In the present research, an available flexural stiffness degradation model was modified and a new comprehensive model called "X-NFSD" was developed. The X-NFSD model is capable of predicting the flexural stiffness degradation of composite specimen at different states of stresses and at room temperature. The model was verified by means of different experimental data for chopped strand mat/epoxy composites under displacement controlled bending loading condition at different displacements and states of stresses. The obtained results provided by the present model are impressively in very good agreement with the experimental data and the mean value of error of 5.4% was achieved.

• 한국재료학회지
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• 제9권8호
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• pp.763-767
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• 1999

자동차, 항공기 및 기타 산업에서 복합재료의 사용은 증가되어 왔고 활발한 연구가 진행되고 있다. 이러한 복합재료중의 하나인 Carbon-epoxy 복합재료의 열 특성에 관하여 알아보았다. 반복적인 냉각과 가열이 부가되는 열 피로에서 복합재료의 탄성계수의 변화를 관찰하여 봄으로써 복합재료가 가지고 있는 여러 열 특성에 관하여 연구하였다. 일반적으로 복합재료는 온도가 증가하면 탄성계수가 감소한다고 알려져 있다. 이러한 결과와는 달리 본 연구에서 수행한 실험에서는 열 피로가 부가되었을 때에는 어느 정도 온도까지는 탄성계수가 증가하다가 다시 감소하는 특이한 현상을 관찰할 수 있었다.