• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1219-1220
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• 2013

• Composites Research
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• 제35권6호
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• pp.419-424
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• 2022

Using non-biodegradable polymers is a severe environmental problem as they are not recyclable and generate a large amount of waste. Biopolymers, such as starch-based composites, have been considered one of the most promising replacement materials. These eco-friendly materials have the advantage of being low-cost, biodegradable, and obtained from renewable sources. However, as starch tends to be brittle and hydrophilic, it can make these materials unusable when exposed to water and limit its processability for further applications. In this work, a biobased modified starch was grafted using two bioderived materials, lauryl methacrylate (LMA) and tetrahydrofurfuryl methacrylate (THFMA), by radical polymerization. A polylactic acid (PLA) composite based on the modified starch (m-St) was fabricated to enhance its toughness. These samples were characterized by Fourier transform infrared, ¹H NMR and ¹³C NMR analysis, optical and scanning electron microscopy. The starch was successfully grafted, thus improving the compatibility with the PLA matrix. The mechanical properties of these films were also studied. Results from mechanical tests showed a slight enhancement of the mechanical performance of these composites when m-St was added to the PLA matrix. Such behavior is related to the improved dispersion of m-St 1:2 on PLA, confirmed by SEM images showing enhanced compatibility between modified starch and PLA matrix. This indicated excellent properties of the produced composite film for further eco-friendly applications.

• Earthquakes and Structures
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• 제23권6호
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• pp.527-534
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• 2022

EDCC (Eco-Friendly Ductile Cementitious Composites) is a recently created class of engineered cementitious composites that exhibit extremely high ductility and elastoplastic behavior under pure tension. EDCC contains reduced amounts of cement and very large volumes of fly ash. Due to these properties, EDCC has become one of the solutions to use in seismic upgrading. This paper discloses previous studies and research that discussed the seismic upgrading of unreinforced, non-grouted, unconfined, and non-load bearing masonry walls which are called URM infill walls using the EDCC technique. URM infill wall is one of the weak links in the building structure to withstand the earthquake waves, as the brittle behavior of the URM infill walls behaves poorly during seismic events. The purpose of this study is to fill a knowledge gap about the theoretical and experimental ways to use the EDCC in URM infill walls. The findings reflect the ability of the EDCC to change the behavior from brittle to ductile to a certain percentage behavior, increasing the overall drift before collapse as it increases the energy dissipation, and resists significant shaking under extensive levels with various types and intensities.

• Composites Research
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• 제22권4호
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• pp.41-49
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• 2009

천연섬유복합재료는 저비용, 경량, 재생성, 친환경적인 재료로 최근 제조되고 있다. 또한 이들 재료는 생체분해성과 비연마 특성을 갖고 있다. 천연섬유의 친환경적이고 생체분해성으로 인해 천연섬유복합재료는 기존의 섬유를 대체할 잠재적인 대체재로 관심을 받고 있다. 천연섬유의 화학적, 기계적, 물리적 특성은 다양한 섬유의 셀룰로스양에 따라 명확한 특정이 구분되며, 이러한 복합재료의 기계적인 물성치는 기지재와 섬유간의 접착에 의해 주로 영향을 받고 있다. 천연섬유표면의 여러 화학적인 물리적인 개질방법은 섬유와 기지의 접착력 향상에 영향을 주어 결국 복합재료의 기계적인 물성치를 향상시킬 수 있다. 본 논문은 최근 개발되고 있는 천연섬유복합재료의 섬유종류, 고분자기지, 제조기술, 섬유의 처리, 섬유 기지간 계면등에 관한 최근의 연구결과들을 정리하여 소개한 것이다.

• Advances in nano research
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• 제15권4호
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• pp.315-328
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• 2023

The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

• Composites Research
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• 제31권6호
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• pp.398-403
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• 2018

최근 플라스틱 폐기물로 인한 환경오염, 미세플라스틱의 생태계 교란 및 인체축적이 큰 문제로 떠오르고 있다. 이를 대체하기 위하여 친환경 수지 및 천연섬유 기반의 복합재료가 개발되어 왔으나 합성섬유 기반의 복합재료에 비하여 기계적 물성이 크게 떨어진다는 단점이 있다. 본 연구에서는 천연섬유인 황마섬유(jute fiber)의 기계적 물성을 향상시키기 위하여 해초로부터 친환경 나노섬유를 추출 후 첨가제로 사용하였다. 핸드 레이업 공정을 이용하여 복합재료를 제조하였으며, 인장, 굽힘, 낙추충격시험을 통하여 나노섬유가 천연섬유 복합재료의 기계적 물성 향상에 효과적임을 확인할 수 있었다.

• Composites Research
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• 제36권1호
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• pp.32-36
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• 2023

최근 탄소 중립 등 지속 가능한 발전을 위한 지구환경 문제가 대두되면서 기존 풍력터빈의 소재인 유리섬유 복합재의 폐기 시 처리 방안이 문제가 되고 있다. 이를 해결하기 위해 본 연구에서는 기존의 유리섬유 복합재를 대체할 수 있는 친환경 복합재인 아마섬유 기반 복합재를 활용하여 30kW 풍력터빈 블레이드를 제조하고 적합성을 평가하였다. 먼저 친환경 천연 아마섬유 복합재의 풍력터빈 블레이드 소재로 활용 가능성을 검증하기 위해 기계적 강도 시험을 수행하였으며, 그 결과 선행 아마섬유 복합재 물성 연구 대비 좀 더 우수한 강도가 측정된 것을 확인하였다. 또한 제작된 30kW 급 아마섬유 복합재 블레이드를 활용하여 아마섬유 복합재 블레이드의 정적강도를 측정하는 정적강도 성능평가 시험을 통하여 적합성을 확인하였다.

• Composites Research
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• 제34권1호
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• pp.57-62
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• 2021

조선해양산업에서 친환경 선박 및 경량화 기자재에 관한 관심이 높아짐에 따라 파이프 등의 기자재에 복합재료를 적용하고 있다. 본 연구에서는 친환경 및 내열/난연 성능을 요구하는 파이프 단열재 커버에 적용하기 위해 친환경 소재인 바잘트 섬유강화 퓨란복합재료(BFC, basalt fiber reinforced furan composite)를 제조하였다. BFC 소재의 낮은 물성을 강화시키기 위해 후경화 조건의 최적화 연구를 수행하였고, BFC 소재의 기계적강도, 내열/난연 특성 강화, 친화경 특성에 대한 실험과 평가를 진행하였다. 최종적으로 연구 결과 조선해양기자재인 파이프 단열재 커버에 BFC 소재의 적용이 가능함을 확인하였다.

• 전기학회논문지
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• 제67권9호
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• pp.1181-1188
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• 2018

In order to develop new insulating materials for GIS Spacer using environmentally friendly insulating gas, three kinds of dispersed liquid nano composites of solid epoxy /nano layered silicate filled material were prepared. And the epoxy/nano/micro silica composite was prepared by mixing epoxy/nano 3 phr dispersion/4 kinds of filler contents(40,50,60, 70wt%). The electrical insulation breakdown strengths of the nano and nano/micro mixed composites were evaluated by using 8 kinds of samples including the original epoxy. The mechanical tensile strength of the epoxy / nano / micro silica composite were evaluated, also. The TEM was measured to evaluate the internal structure of nano/micro composites. As a result, it was confirmed that the layered silicate nano particles was exfoliated through the process of inserting epoxy resin between silicate layers and the layers. In addition, dispersion of nano / micro silica resulted in improvement of electrical insulation breakdown strength with increase of filling amount of dense tissue with nanoparticles inserted between microparticles. In addition, the tensile strength showed a similar tendency, and as the content of microsilica filler increased, the mechanical improvement was further increased.

• 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.