• Composites Research
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• 제34권6호
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• pp.345-349
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• 2021

The continued environmental pollution caused by fossil fuel consumption has prompted researchers around the world to develop environmentally friendly energy technologies. Electrochemical energy storage is the significant area of research in this development process, and the research significance of supercapacitors in this field is increasing. Herein, a simple electrodeposition synthetic route was explored to develop the MoP layered cathode material. The layered structure provided a highly ion-accessible surface for smooth and faster ion adsorption/desorption. After Fe was doped into MoP, the morphology of MoP changes and the electrochemical performance was significantly improved. Specific capacitance value of the binder-free FeMoP electrode was found to be 269 F g^-1 at 2 A g^-1 current density in 6 M aqueous KOH electrolyte. After adding Fe to MoP, an additional redox contribution was observed in the redox conversion from Fe³⁺ to Fe²⁺ redox pair, and the charge transfer kinetics of MoP was effectively improved. This research can provide guidance for the development of supercapacitor electrode materials through simple electrodeposition technology.

• Advances in nano research
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• 제14권3호
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• pp.261-271
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• 2023

The present study follows three main goals. First, an analytical solution with high accuracy is developed to assess the effects of embedding pre-strained shape memory alloy (SMA) wires on the critical buckling temperatures of rectangular sandwich plates made of soft core and graphite fiber/epoxy (GF/EP) face sheets based on piecewise low-order shear deformation theory (PLSDT) using Brinson's model. As the second goal, this study compares the effects of SMAs on the thermal buckling of sandwich plates with those of carbon nanotubes (CNTs). The glass transition temperature is considered as a limiting factor. For each material, the effective ranges of operating temperature and thickness ratio are determined for real situations. The results indicate that depending on the geometric parameters and thermal conditions, one of the SMAs and CNTs may outperform the other. The third purpose is to study the thermal buckling of sandwich plates with advanced hybrid SMA/CNT/GF/EP composite face sheets. It is shown that in some circumstances, the co-incorporation of SMAs and CNTs leads to an astonishing enhancement in the critical buckling temperatures of sandwich plates.

• Advances in nano research
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• 제14권6호
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• pp.541-555
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• 2023

The extensive use of polymeric matrix composites in the athletic sector may be attributed to its high strength-to-weight ratio, production economy, and a longer lifespan than conventional materials. This study explored the impact of carbon nanotubes on the properties of different composite field sports equipment components. The test specimens were fabricated using the compression molding technique. The insertion of carbon nanotubes increases mechanical properties related to the process parameters to account for an improvement in the stick sections' overall performance. The dynamic response of functionally graded reinforced nanocomposite wire structure is examined in this paper on the bases of high-order hyperbolic beam theory lined to the size-dependent nonclassical nonlocal theory under the external mechanical load due to the physical activities. Finally, the impact of different parameters on the stability of nanocomposite structures is discussed in detail.

• Advances in nano research
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• 제14권6호
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• pp.557-573
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• 2023

The rapid growth of zinc-oxide (ZnO) nanostructures (NSs) on woven carbon fiber (WCF) is reported in this study employing a microwave-aided chemical bath deposition process. The effects of different process parameters such as molar concentration, microwave duration and microwave power on morphologies and growth rate of the ZnO on WCF were studied. Furthermore, an attempt has been taken to study influence of different type of growth solutions on ZnO morphologies and growth rates. The surface functionalization of WCF fabrics is achieved by successful growth of crystalline ZnO on fiber surface in a very short duration through one-step microwave synthesis. The morphological, structural and compositional studies of ZnO-modified WCF are evaluated using field-emission scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy respectively. Good amount of zinc and oxygen has been seen in the surface of WCF. The presence of the wurtzite phase of ZnO having crystallite size 30-40 nm calculated using the Debye Scherrer method enhances the surface characteristics of WCF fabrics. The UV-VIS spectroscopy is used to investigate optical properties of ZnO-modified WCF samples by absorbance, transmittance and reflectance spectra. The variation of different parameters such as dielectric constants, optical conductivity, refractive index and extinction coefficient are examined that revealed the enhancement of optical characteristics of carbon fiber for wide applications in optoelectronic devices, carbon fiber composites and photonics.

• Advances in nano research
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• 제15권4호
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• pp.367-384
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• 2023

Natural frequency behavior of graphene platelets reinforced composite (GPL-RC) joined truncated conical-cylindrical- conical shells resting on Winkler-type elastic foundation is presented in this paper for the first time. The rule of mixture and the modified Halpin-Tsai approach are applied to achieve the mechanical properties of the structure. Four different graphene platelets patterns are considered along the thickness of the structure such as GPLA, GPLO, GPLX, GPLUD. Finite element procedure according to Rayleigh-Ritz formulation has been used to solve 2D-axisymmetric elasticity equations. Application of 2D axisymmetric elasticity theory allows thickness stretching unlike simple shell theories, and this gives more accurate results, especially for thick shells. An efficient parametric investigation is also presented to show the effects of various geometric variables, three different boundary conditions, stiffness of elastic foundation, dispersion pattern and weight fraction of GPLs nanofillers on the natural frequencies of the joined shell. Results show that GPLO and BC3 provide the most rigidity that cause the most natural frequencies among different BCs and GPL patterns. Also, by increasing the weigh fraction of nanofillers, the natural frequencies will increase up to 200%.

• Advances in nano research
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• 제16권1호
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• pp.81-90
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• 2024

In the oil and gas industry, composite materials should exhibit high flexibility and strength for offshore structures. Therefore, weak points in the composites should be improved, such as brittleness, moisture penetration, and diffusion of detrimental ions into nanometric pores. This study aimed to increase the strength, flexibility, and plugging of nanopores using single-layer graphene oxide (SGO) nanosheets. Therefore, SGO is added to unsaturated polyester resin at concentrations of 0.015 and 0.15 % with Normal Methyl Pyrrolidone (NMP) as a solvent for the formation of Nanographene Oxide Reinforced Polymer (NGORP). The mechanical properties of the prepared samples were tested using tensile testing (ASTM-D 638). It has been shown that incorporating SGO, approximately 0.015%, into the base resin resulted in enhanced properties such as rupture resistance forces increased by 745.61 N, applied stress tolerances increased by 4.1 MPa, longitude increased to 1.58 mm, elongation increased by about 2.38%, and rupture energy increased by about 204.51 J. Despite the decrease in tensile force strength properties in the manufactured nanocomposite with 0.15% SGO, it has exclusive flexibility properties such as a high required energy level for rupture of 5,576 times and a formability of 40% more than the base sample. It would be best to use NGORP manufactured from 0.015% nanosheets with exclusive properties rather than base samples for constructing parts and equipment, such as rebars, composite sheets, and transmission pipes, on offshore platforms.

• Archives of Metallurgy and Materials
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• 제66권3호
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• pp.799-802
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• 2021

The nano-sized Y₂O₃ dispersed W composite powder is prepared by ultrasonic spray pyrolysis of a tungsten precursor using ammonium metatungstate hydrate and a polymer addition solution method using Y-nitrate. XRD analysis for calcined powder showed the formation of WO₂ phase by partial oxidation of W powder during calcination in air. The TEM and phase analysis for further hydrogen reduction of calcined powder mixture exhibited that the W powder with a uniform distribution of Y₂O₃ nanoparticles can be successfully produced. These results indicate that the wet chemical method combined with spray pyrolysis and polymer solution is a promising way to synthesis the W-based composites with homogeneous dispersion of fine oxide particles.

• 폴리머
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• 제39권1호
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• pp.23-32
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• 2015

상 전이 물질인 파라핀 왁스를 초고분자량 폴리에틸렌(UHMWPE)과의 absorption method를 통해 파우더를 제조 후 hot press를 사용하여 형태안정성 상 전이 물질(SSPCM) composite를 제조하였다. SSPCM composite의 화학, 미세구조, 형태, 열적, 결정구조, 유변학적 특성을 조사하기 위하여 FTIR, SEM, DSC, XRD, ARES 측정을 하였다. FTIR 분석결과 파라핀 및 UHMWPE의 고유 피크들이 나타나고 있는 것을 확인하였고, SEM 분석결과 파라핀의 농도가 40 wt%까지는 표면이 상당히 팽윤되며 거친 특성을 나타냄을 확인할 수 있었고, DSC 분석결과 SSPCM에서 파라핀 및 UHMWPE의 고유 융점들이 나타났고, XRD 분석에서는 파라핀과 UHMWPE의 $2{\theta}$ 값들이 SSPCM에서도 나타남을 확인할 수 있었고, ARES 분석에서는 파라핀 농도에 따른 G', G", $tan{\delta}$ 값의 변화를 확인할 수 있었다. 종합적인 분석 결과를 통해, 파라핀의 농도가 30 wt%일 때, 형태안정성 측면에서 최적의 농도임을 확인할 수 있었다.

• 한국전산구조공학회논문집
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• 제31권4호
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• pp.173-181
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• 2018

최근 복합재료는 향상된 성능, 내구성 및 여러 특정 요구성능에 대한 설계 유연성으로 인해 다양한 분야에서 활발히 활용되고 있다. 컴퓨터 성능이 발달함에 따라, 복합재료의 복잡한 거동에 대한 정확도 높은 모델 역시 함께 연구되고 있으며, 이로 인해 가상시험이 복합재료 거동에 대한 실험을 대체하거나 보충하는데 중요한 역할을 하고 있다. 본 논문에서는 나노수준부터 구조물 단위까지 이르는 다양한 length scale의 homogenization을 통한 멀티스케일 모델링에 대한 문헌을 분석하였다. 또한, 콘크리트 거동 연구에 대한 통합모델의 특징을 다루었으며, 가상 시험기계에 대한 최근 연구동향 및 전망에 대하여 다루었다.

• Composites Research
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• 제34권6호
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• pp.357-372
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• 2021

에너지 수확장치는 석유자원의 고갈로 인한 자원난을 해결할 수 있는 대안으로 유망하다고 알려져 있다. 기계적 움직임을 전기 에너지로 전환할 수 있는 압전 소자들의 한계(환경오염 및 낮은 기계적 특성)를 극복하기 위하여, 고분자 기지재 기반 복합재료 압전 에너지 수확장치에 대한 많은 연구들이 수행되었다. 본 논문에서는 사용된 재료 및 공정에 기초하여, 보고된 압전 복합재료의 출력 성능 및 관련된 응용 분야를 검토하였다. 압전 필러는 티탄산 지르콘산 연 및 티탄산바륨 기반의 세라믹 필러뿐만 아니라, 친환경, 생체적합성 및 유연성 측면에서 유리한 산화아연을 검토하였다. 기지재는 폴리비닐리덴플로오라이드 및 공중합체로 구성된 압전 고분자 및 에폭시 및 폴리디메틸실록산 기반의 유연한 고분자로 분류하여 복합재료의 압전 시너지 및 높은 외력 적용에 의한 압전 출력 향상을 논의하였다. 또한, 금속 혹은 탄소 소재 기반 2차 필러의 적용에 의한 복합재료의 전도성 혹은 기계적 특성의 향상이 압전 수확장치의 출력 성능에 미치는 영향을 복합재료의 구조 측면에서 검토하였다. 향상된 성능으로 소형 전자기기, 스마트 센서, 의학 분야 등에 응용 가능한 복합재료 기반 압전 수확장치는 미래의 일상에서 접할 수 있는 무선 전자 장치의 전원으로써 잠재적인 통찰을 제공할 수 있다.