• Composites Research
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• 제28권2호
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• pp.29-39
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• 2015

Natural fibers reinforced polymer composites are being used in several low strength applications. More research is going on to improve their mechanical and interface properties for structural applications. However, these composites have serious issues regarding flammability, which are not being focused broadly. A limited amount of literature has been published on the flame retardant techniques and flammability factor of natural fibers based polymer matrix composites. Therefore, it is needed to address the flammability properties of natural fibers based polymer composites to expand their application area. This paper summarizes some of the recent literature published on the subject of flammability and flame retardant methods applied to natural fibers reinforced polymer matrix composites. Different factors affecting the flammability, flame retardant solutions, mechanisms and characterization techniques have been discussed in detail.

• 한국전기전자재료학회논문지
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• 제34권4호
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• pp.229-241
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• 2021

Since 2010, polymer-based magnetoelectric (ME) composites have been developed with detailed investigations of multiferroic properties such as piezoelectric, magnetostrictive, and magnetoelectric, etc. In particular, as a piezoelectric polymer, poly(vinylidene fluoride) and its co-polymers have been widely used in ME composites for energy harvesting, health monitoring, environment treatment, and bio-medical applications. In this study, main research trend and selected experimental results of polymer-based ME composites are briefly reviewed with respect to composite structure as well as application field. A conclusion was drawn that the polymer-based ME composites would be feasible as flexible devices or functional membranes in the near future.

• Macromolecular Research
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• 제13권1호
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• pp.19-29
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• 2005

Polymer composites based on a thermotropic liquid-crystalline polymer (TLCP) and poly(butylene terephthalate) (PBT) were prepared using a melt blending process. Polymer composites consisting of bulk cheap polyester with a small quantity of expensive TLCP are of interest from a commercial perspective. The interactions between the PBT chains and the flexible poly(ethylene terephthalate) (PET) units in the TLCP phase resulted in an improvement in the compatibility of PBT/TLCP composites. TLCP droplets deformed and fragmented into smaller droplets in the PBT/TLCP composites, which resulted in TLCP fibrillation through the effective deformation of the TLCP droplets. The nucleation activities of the PBT/TLCP composites increased by adding even a small amount of the TLCP component.

• Composites Research
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• 제35권5호
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• pp.359-364
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• 2022

Polymers are inherently vulnerable to flame, which limits their application to various high-tech industries. In addition, environmental regulations restrict the use of halogen-based flame retardants which has best flame-retardant effect. There are inorganic flame retardants and phosphorous flame retardants as representative non-halogen-based flame retardants. However, high content of flame retardants is required to impart high flame retardancy of the polymers, and this leads to a decrease in mechanical properties. In this research, a new approach for inorganic flame retardant-based polymer composites with high mechanical properties and flame retardancy was suggested. Inorganic flame retardants called as magnesium oxysulfate whisker (MOSw) were used in this research. MOSw can extinguish fire by releasing water and non-combustible gases when exposed to flame. In addition, they have reinforcing effect when added into the polymer with its high aspect ratio. Expandable graphite (EG) was used as a flame-retardant supplement by helping to form a more dense char layer. Through this research, it is expected that it can be applied to various industries requiring flame retardancy such as automobile, and architecture by replacing halogen-based flame polymer composites.

• Carbon letters
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• 제11권4호
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• pp.347-356
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• 2010

Recently, the use of thermal conductive polymeric composites is growing up, where the polymers filled with the thermally conductive fillers effectively dissipate heat generated from electronic components. Therefore, the management of heat is directly related to the lifetime of electronic devices. For the purpose of the improvement of thermal conductivity of composites, fillers with excellent thermally conductive behavior are commonly used. Thermally conductive particles filled polymer composites have advantages due to their easy processibility, low cost, and durability to the corrosion. Especially, carbon-based 1-dimensional nanomaterials such as carbon nanotube (CNT) and carbon nanofiber (CNF) have gained much attention for their excellent thermal conductivity, corrosion resistance and low thermal expansion coefficient than the metals. This paper aims to review the research trends in the improvement of thermal conductivity of the carbon-based materials filled polymer composites.

• 한국재료학회지
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• 제25권12호
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• pp.678-682
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• 2015

The electrical property of polymer matrix composites with added carbon powder is studied based on the temperature dependency of the conduction mechanism. The temperature coefficient of the resistance of the polymer matrix composites below the percolation threshold (x) changed from negative to positive at 0.20 < x < 0.21; this trend decreased with increasing of the percolation threshold. The temperature dependence of the electrical property(resistivity) of the polymer matrix composites below the percolation threshold can be explained by using a tunneling conduction model that incorporates the effect of the thermal expansion of the polymer matrix composites into the tunneling gap. The temperature coefficient of the resistance of the polymer matrix composites above the percolation threshold has a positive value; its absolute value increased with increasing volume fraction of carbon powder. By assuming that the electrical conduction through the percolating paths is a thermally activated process and by incorporating the effect of thermal expansion into the volume fraction of the carbon power, the temperature dependency of the resistivity above the percolation threshold can be well explained without violating the universal law of conductivity.

• Carbon letters
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• 제5권3호
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• pp.127-132
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• 2004

Chop molding composites and 2D carbon/carbon composites were manufactured by hot press molding method. Phenol resin of novolac type was used for matrix precursor and PAN-based carbon, PAN-based graphite and pitch-based carbon fiber were used for reinforcement and boron oxide was used for oxidation retardant. All of the composites were treated by $2000^{\circ}C$ and $2400^{\circ}C$ graphitization process, respectively. After graphitization process, amount of a boron residue in carbon/carbon composites is much according to irregularity of used raw materials. Under the presence of boron in carbon/carbon composites, catalytic effect of boron was a little at $2000^{\circ}C$ graphitization temperature. However, it was quite at $2400^{\circ}C$ graphitization.

• Carbon letters
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• 제12권2호
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• pp.57-69
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• 2011

Carbon nanotubes (CNTs) have high Young's modulus, low density, and excellent electrical and thermal properties, which make them ideal fillers for polymer composites. Homogeneous dispersion of CNTs in a polymer matrix plays a crucial role in the preparation of polymer composites based on interfacial interactions between CNTs and the polymer matrix. The addition of a small amount of CNTs strongly improves the electrical, thermal, and mechanical properties of the composites. This paper aims to review the processing technology and improvement of properties of CNT-reinforced polymer composites.

• Interaction and multiscale mechanics
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• 제4권3호
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• pp.173-185
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• 2011

A multiscale modeling scheme that addresses the influence of the nanoparticle size in nanocomposites consisting of nano-sized spherical particles embedded in a polymer matrix is presented. A micromechanics-based constitutive model for nanoparticle-reinforced polymer composites is derived by incorporating the Eshelby tensor considering the interface effects (Duan et al. 2005a) into the ensemble-volume average method (Ju and Chen 1994). A numerical investigation is carried out to validate the proposed micromechanics-based constitutive model, and a parametric study on the interface moduli is conducted to investigate the effect of interface moduli on the overall behavior of the composites. In addition, molecular dynamics (MD) simulations are performed to determine the mechanical properties of the nanoparticles and polymer. Finally, the overall elastic moduli of the nanoparticle-reinforced polymer composites are estimated using the proposed multiscale approach combining the ensemble-volume average method and the MD simulation. The predictive capability of the proposed multiscale approach has been demonstrated through the multiscale numerical simulations.

• 한국농공학회논문집
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• 제47권6호
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• pp.27-34
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• 2005

The purpose of this study is to improve the durability performance of polymer modified cement composites for repair of concrete under combined aging conditions. The experimental procedure was divided into three parts. First, the replacement level of mineral admixtures in polymer modified cement composites were determined in an experimental study based on a Box Behnken design. Second, the flow value, compressive strength and chloride permeability test of sixteen types of mixtures were conducted. Test results show that the polymer modified cement composites were effected on the improvement of the compressive strength and permeability performance. Third, the effects on the replacement level of silica fume mixture was evaluated by the compressive strength, chloride permeability, chemical resistance and repeated freezing and thawing cycles test. They demonstrated that the polymer modified cement composites using mixture of silica fume, fly ash, and blast furnace slag improved the durability performance.